# groff-1   [plain text]

This is groff, produced by makeinfo version 4.8 from ./groff.texinfo.

This manual documents GNU troff' version 1.19.2.

Copyright (C) 1994-2000, 2001, 2002, 2003, 2004, 2005 Free Software
Foundation, Inc.

Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Foundation; with no Invariant Sections, with the Front-Cover texts
being A GNU Manual," and with the Back-Cover Texts as in (a)
below.  A copy of the license is included in the section entitled

(a) The FSF's Back-Cover Text is: You have freedom to copy and
the Free Software Foundation raise funds for GNU development."

INFO-DIR-SECTION Typesetting
START-INFO-DIR-ENTRY
* Groff: (groff).               The GNU troff document formatting system.
END-INFO-DIR-ENTRY

File: groff,  Node: Top,  Next: Introduction,  Prev: (dir),  Up: (dir)

GNU troff
*********

This manual documents GNU troff' version 1.19.2.

Copyright (C) 1994-2000, 2001, 2002, 2003, 2004, 2005 Free Software
Foundation, Inc.

Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Foundation; with no Invariant Sections, with the Front-Cover texts
being A GNU Manual," and with the Back-Cover Texts as in (a)
below.  A copy of the license is included in the section entitled

(a) The FSF's Back-Cover Text is: You have freedom to copy and
the Free Software Foundation raise funds for GNU development."

* Introduction::
* Invoking groff::
* Tutorial for Macro Users::
* Macro Packages::
* gtroff Reference::
* Preprocessors::
* Output Devices::
* File formats::
* Installation::
* Copying This Manual::
* Request Index::
* Escape Index::
* Operator Index::
* Register Index::
* Macro Index::
* String Index::
* Glyph Name Index::
* Font File Keyword Index::
* Program and File Index::
* Concept Index::

File: groff,  Node: Introduction,  Next: Invoking groff,  Prev: Top,  Up: Top

1 Introduction
**************

GNU troff' (or groff') is a system for typesetting documents.
troff' is very flexible and has been in existence (and use) for about
3 decades.  It is quite widespread and firmly entrenched in the UNIX
community.

* What Is groff?::
* History::
* groff Capabilities::
* Macro Package Intro::
* Preprocessor Intro::
* Output device intro::
* Credits::

File: groff,  Node: What Is groff?,  Next: History,  Prev: Introduction,  Up: Introduction

1.1 What Is groff'?
====================

groff' belongs to an older generation of document preparation systems,
which operate more like compilers than the more recent interactive
WYSIWYG(1) (*note What Is groff?-Footnote-1::) systems.  groff' and
its contemporary counterpart, TeX, both work using a "batch" paradigm:
The input (or "source") files are normal text files with embedded
formatting commands.  These files can then be processed by groff' to
produce a typeset document on a variety of devices.

Likewise, groff' should not be confused with a "word processor",
since that term connotes an integrated system that includes an editor
and a text formatter.  Also, many word processors follow the WYSIWYG

Although WYSIWYG systems may be easier to use, they have a number of

* They must be used on a graphics display to work on a document.

* Most of the WYSIWYG systems are either non-free or are not very
portable.

* troff' is firmly entrenched in all UNIX systems.

* It is difficult to have a wide range of capabilities available
within the confines of a GUI/window system.

* It is more difficult to make global changes to a document.

"GUIs normally make it simple to accomplish simple actions and
impossible to accomplish complex actions."  -Doug Gwyn (22/Jun/91
in comp.unix.wizards')

File: groff,  Node: What Is groff?-Footnotes,  Up: What Is groff?

(1) What You See Is What You Get

File: groff,  Node: History,  Next: groff Capabilities,  Prev: What Is groff?,  Up: Introduction

1.2 History
===========

troff' can trace its origins back to a formatting program called
runoff', written by J. E. Saltzer, which ran on MIT's CTSS operating
system in the mid-sixties.  This name came from the common phrase of
the time "I'll run off a document."  Bob Morris ported it to the 635
architecture and called the program roff' (an abbreviation of
runoff').  It was rewritten as rf' for the PDP-7 (before having
UNIX), and at the same time (1969), Doug McIllroy rewrote an extended
and simplified version of roff' in the BCPL programming language.

The first version of UNIX was developed on a PDP-7 which was sitting
around Bell Labs.  In 1971 the developers wanted to get a PDP-11 for
further work on the operating system.  In order to justify the cost for
this system, they proposed that they would implement a document
formatting system for the AT&T patents division.  This first formatting
program was a reimplementation of McIllroy's roff', written by
J. F. Ossanna.

When they needed a more flexible language, a new version of roff'
called nroff' ("Newer roff'") was written.  It had a much more
complicated syntax, but provided the basis for all future versions.
When they got a Graphic Systems CAT Phototypesetter, Ossanna wrote a
version of nroff' that would drive it.  It was dubbed troff', for
"typesetter roff'", although many people have speculated that it
actually means "Times roff'" because of the use of the Times font
family in troff' by default.  As such, the name troff' is pronounced
t-roff' rather than trough'.

With troff' came nroff' (they were actually the same program
except for some #ifdef's), which was for producing output for line
printers and character terminals.  It understood everything troff'
did, and ignored the commands which were not applicable (e.g. font
changes).

Since there are several things which cannot be done easily in
troff', work on several preprocessors began.  These programs would
transform certain parts of a document into troff', which made a very
natural use of pipes in UNIX.

The eqn' preprocessor allowed mathematical formulæ to be specified
in a much simpler and more intuitive manner.  tbl' is a preprocessor
for formatting tables.  The refer' preprocessor (and the similar
program, bib') processes citations in a document according to a
bibliographic database.

Unfortunately, Ossanna's troff' was written in PDP-11 assembly
language and produced output specifically for the CAT phototypesetter.
He rewrote it in C, although it was now 7000 lines of uncommented code
and still dependent on the CAT.  As the CAT became less common, and was
no longer supported by the manufacturer, the need to make it support
other devices became a priority.  However, before this could be done,
Ossanna was killed in a car accident.

So, Brian Kernighan took on the task of rewriting troff'.  The
newly rewritten version produced device independent code which was very
easy for postprocessors to read and translate to the appropriate
printer codes.  Also, this new version of troff' (called ditroff' for
"device independent troff'") had several extensions, which included
drawing functions.

Due to the additional abilities of the new version of troff',
several new preprocessors appeared.  The pic' preprocessor provides a
wide range of drawing functions.  Likewise the ideal' preprocessor did
the same, although via a much different paradigm.  The grap'
preprocessor took specifications for graphs, but, unlike other
preprocessors, produced pic' code.

James Clark began work on a GNU implementation of ditroff' in
early 1989.  The first version, groff' 0.3.1, was released June 1990.
groff' included:

* A replacement for ditroff' with many extensions.

* The soelim', pic', tbl', and eqn' preprocessors.

* Postprocessors for character devices, POSTSCRIPT, TeX DVI, and
X Windows.  GNU troff' also eliminated the need for a separate
nroff' program with a postprocessor which would produce ASCII
output.

* A version of the me' macros and an implementation of the man'
macros.

Also, a front-end was included which could construct the, sometimes
painfully long, pipelines required for all the post- and preprocessors.

Development of GNU troff' progressed rapidly, and saw the additions
of a replacement for refer', an implementation of the ms' and mm'
macros, and a program to deduce how to format a document (grog').

It was declared a stable (i.e. non-beta) package with the release of
version 1.04 around November 1991.

Beginning in 1999, groff' has new maintainers (the package was an
orphan for a few years).  As a result, new features and programs like
grn', a preprocessor for gremlin images, and an output device to
produce HTML output have been added.

File: groff,  Node: groff Capabilities,  Next: Macro Package Intro,  Prev: History,  Up: Introduction

1.3 groff' Capabilities
========================

So what exactly is groff' capable of doing?  groff' provides a wide
range of low-level text formatting operations.  Using these, it is
possible to perform a wide range of formatting tasks, such as
the most important operations supported by groff':

* text filling, adjusting, and centering

* hyphenation

* page control

* font and glyph size control

* vertical spacing (e.g. double-spacing)

* line length and indenting

* macros, strings, diversions, and traps

* number registers

* input and output conventions and character translation

* overstrike, bracket, line drawing, and zero-width functions

* local horizontal and vertical motions and the width function

* three-part titles

* output line numbering

* conditional acceptance of input

* environment switching

* insertions from the standard input

* input/output file switching

* output and error messages

File: groff,  Node: Macro Package Intro,  Next: Preprocessor Intro,  Prev: groff Capabilities,  Up: Introduction

1.4 Macro Packages
==================

Since groff' provides such low-level facilities, it can be quite
difficult to use by itself.  However, groff' provides a "macro"
facility to specify how certain routine operations (e.g. starting
paragraphs, printing headers and footers, etc.)  should be done.  These
macros can be collected together into a "macro package".  There are a
number of macro packages available; the most common (and the ones
described in this manual) are man', mdoc', me', ms', and mm'.

File: groff,  Node: Preprocessor Intro,  Next: Output device intro,  Prev: Macro Package Intro,  Up: Introduction

1.5 Preprocessors
=================

Although groff' provides most functions needed to format a document,
some operations would be unwieldy (e.g. to draw pictures).  Therefore,
programs called "preprocessors" were written which understand their own
language and produce the necessary groff' operations.  These
preprocessors are able to differentiate their own input from the rest
of the document via markers.

To use a preprocessor, UNIX pipes are used to feed the output from
the preprocessor into groff'.  Any number of preprocessors may be used
on a given document; in this case, the preprocessors are linked
together into one pipeline.  However, with groff', the user does not
need to construct the pipe, but only tell groff' what preprocessors to
use.

groff' currently has preprocessors for producing tables (tbl'),
typesetting equations (eqn'), drawing pictures (pic' and grn'), and
for processing bibliographies (refer').  An associated program which
is useful when dealing with preprocessors is soelim'.

A free implementation of grap', a preprocessor for drawing graphs,
can be obtained as an extra package; groff' can use grap' also.

There are other preprocessors in existence, but, unfortunately, no
free implementations are available.  Among them are preprocessors for
drawing mathematical pictures (ideal') and chemical structures
(chem').

File: groff,  Node: Output device intro,  Next: Credits,  Prev: Preprocessor Intro,  Up: Introduction

1.6 Output Devices
==================

groff' actually produces device independent code which may be fed into
a postprocessor to produce output for a particular device.  Currently,
groff' has postprocessors for POSTSCRIPT devices, character terminals,
X Windows (for previewing), TeX DVI format, HP LaserJet 4 and Canon LBP
printers (which use CAPSL), and HTML.

File: groff,  Node: Credits,  Prev: Output device intro,  Up: Introduction

1.7 Credits
===========

Large portions of this manual were taken from existing documents, most
notably, the manual pages for the groff' package by James Clark, and
Eric Allman's papers on the me' macro package.

The section on the man' macro package is partly based on Susan G.
Kleinmann's groff_man' manual page written for the Debian GNU/Linux
system.

Larry Kollar contributed the section in the ms' macro package.

File: groff,  Node: Invoking groff,  Next: Tutorial for Macro Users,  Prev: Introduction,  Up: Top

2 Invoking groff'
******************

This section focuses on how to invoke the groff' front end.  This
front end takes care of the details of constructing the pipeline among
the preprocessors, gtroff' and the postprocessor.

It has become a tradition that GNU programs get the prefix g' to
distinguish it from its original counterparts provided by the host (see
*Note Environment::, for more details).  Thus, for example, geqn' is
GNU eqn'.  On operating systems like GNU/Linux or the Hurd, which
don't contain proprietary versions of troff', and on
MS-DOS/MS-Windows, where troff' and associated programs are not
available at all, this prefix is omitted since GNU troff' is the only
used incarnation of troff'.  Exception: groff' is never replaced by
roff'.

In this document, we consequently say gtroff' when talking about
the GNU troff' program.  All other implementations of troff' are
called AT&T troff' which is the common origin of all troff' derivates
(with more or less compatible changes).  Similarly, we say gpic',
geqn', etc.

* Groff Options::
* Environment::
* Macro Directories::
* Font Directories::
* Paper Size::
* Invocation Examples::

File: groff,  Node: Groff Options,  Next: Environment,  Prev: Invoking groff,  Up: Invoking groff

2.1 Options
===========

groff' normally runs the gtroff' program and a postprocessor
appropriate for the selected device.  The default device is ps' (but
it can be changed when groff' is configured and built).  It can
optionally preprocess with any of gpic', geqn', gtbl', ggrn',
grap', grefer', or gsoelim'.

This section only documents options to the groff' front end.  Many
of the arguments to groff' are passed on to gtroff', therefore those
are also included.  Arguments to pre- or postprocessors can be found in
*Note Invoking gpic::, *Note Invoking geqn::, *Note Invoking gtbl::,
*Note Invoking ggrn::, *Note Invoking grefer::, *Note Invoking
gsoelim::, *Note Invoking grotty::, *Note Invoking grops::, *Note
Invoking grohtml::, *Note Invoking grodvi::, *Note Invoking grolj4::,
*Note Invoking grolbp::, and *Note Invoking gxditview::.

The command line format for groff' is:

groff [ -abceghilpstvzCEGNRSUVXZ ] [ -FDIR ] [ -mNAME ]
[ -TDEF ] [ -fFAM ] [ -wNAME ] [ -WNAME ]
[ -MDIR ] [ -dCS ] [ -rCN ] [ -nNUM ]
[ -oLIST ] [ -PARG ] [ -LARG ] [ -IDIR ]
[ FILES... ]

The command line format for gtroff' is as follows.

gtroff [ -abcivzCERU ] [ -wNAME ] [ -WNAME ] [ -dCS ]
[ -fFAM ] [ -mNAME ] [ -nNUM ]
[ -oLIST ] [ -rCN ] [ -TNAME ]
[ -FDIR ] [ -MDIR ] [ FILES... ]

Obviously, many of the options to groff' are actually passed on to
gtroff'.

Options without an argument can be grouped behind a single -'.  A
filename of -' denotes the standard input.  It is possible to have
whitespace between an option and its parameter.

The grog' command can be used to guess the correct groff' command
to format a file.

Here's the description of the command-line options:

-h'
Print a help message.

-e'
Preprocess with geqn'.

-t'
Preprocess with gtbl'.

-g'
Preprocess with ggrn'.

-G'
Preprocess with grap'.

-p'
Preprocess with gpic'.

-s'
Preprocess with gsoelim'.

-c'
Suppress color output.

-R'
Preprocess with grefer'.  No mechanism is provided for passing
arguments to grefer' because most grefer' options have
equivalent commands which can be included in the file.  *Note
grefer::, for more details.

Note that gtroff' also accepts a -R' option, which is not
troffrc' and troffrc-end' files.

-v'
Make programs run by groff' print out their version number.

-V'
Print the pipeline on stdout' instead of executing it.  If
specified more than once, print the pipeline on stderr' and
execute it.

-z'
Suppress output from gtroff'.  Only error messages are printed.

-Z'
Do not postprocess the output of gtroff'.  Normally groff'
automatically runs the appropriate postprocessor.

-PARG'
Pass ARG to the postprocessor.  Each argument should be passed
with a separate -P' option.  Note that groff' does not prepend
-' to ARG before passing it to the postprocessor.

-l'
Send the output to a spooler for printing.  The command used for
this is specified by the print' command in the device description
-l' is ignored.

-LARG'
Pass ARG to the spooler.  Each argument should be passed with a
separate -L' option.  Note that groff' does not prepend a -' to
ARG before passing it to the postprocessor.  If the print'
keyword in the device description file is missing, -L' is ignored.

-TDEV'
Prepare output for device DEV.  The default device is ps', unless
changed when groff' was configured and built.  The following are
the output devices currently available:

ps'
For POSTSCRIPT printers and previewers.

dvi'
For TeX DVI format.

X75'
For a 75dpi X11 previewer.

X75-12'
For a 75dpi X11 previewer with a 12pt base font in the
document.

X100'
For a 100dpi X11 previewer.

X100-12'
For a 100dpi X11 previewer with a 12pt base font in the
document.

ascii'
For typewriter-like devices using the (7-bit) ASCII character
set.

latin1'
For typewriter-like devices that support the Latin-1
(ISO 8859-1) character set.

utf8'
For typewriter-like devices which use the Unicode (ISO 10646)
character set with UTF-8 encoding.

cp1047'
For typewriter-like devices which use the EBCDIC encoding IBM
cp1047.

lj4'
For HP LaserJet4-compatible (or other PCL5-compatible)
printers.

lbp'
For Canon CAPSL printers (LBP-4 and LBP-8 series laser
printers).

html'
To produce HTML output.  Note that the HTML driver consists
of two parts, a preprocessor (pre-grohtml') and a
postprocessor (post-grohtml').

The predefined gtroff' string register .T' contains the current
output device; the read-only number register .T' is set to 1 if
this option is used (which is always true if groff' is used to
call gtroff').  *Note Built-in Registers::.

The postprocessor to be used for a device is specified by the
postpro' command in the device description file.  (*Note Font
option.

-X'
Preview with gxditview' instead of using the usual postprocessor.
This is unlikely to produce good results except with -Tps'.

Note that this is not the same as using -TX75' or -TX100' to
view a document with gxditview': The former uses the metrics of
the specified device, whereas the latter uses X-specific fonts and
metrics.

-N'
Don't allow newlines with eqn' delimiters.  This is the same as
the -N' option in geqn'.

-S'
Safer mode.  Pass the -S' option to gpic' and disable the
open', opena', pso', sy', and pi' requests.  For security
reasons, this is enabled by default.

-U'
Unsafe mode.  This enables the open', opena', pso', sy', and
pi' requests.

-a'
Generate an ASCII approximation of the typeset output.  The
read-only register .A' is then set to 1.  *Note Built-in
Registers::.  A typical example is

groff -a -man -Tdvi troff.man | less

which shows how lines are broken for the DVI device.  Note that
this option is rather useless today since graphic output devices
are available virtually everywhere.

-b'
Print a backtrace with each warning or error message.  This
backtrace should help track down the cause of the error.  The line
numbers given in the backtrace may not always be correct: gtroff'
can get confused by as' or am' requests while counting line
numbers.

-i'
Read the standard input after all the named input files have been
processed.

-wNAME'
Enable warning NAME.  Available warnings are described in *Note
Debugging::.  Multiple -w' options are allowed.

-WNAME'
Inhibit warning NAME.  Multiple -W' options are allowed.

-E'
Inhibit all error messages.

-C'
Enable compatibility mode.  *Note Implementation Differences::,
for the list of incompatibilities between groff' and AT&T troff'.

-dCS'
-dNAME=S'
Define C or NAME to be a string S.  C must be a one-letter name;
NAME can be of arbitrary length.  All string assignments happen

-fFAM'
Use FAM as the default font family.  *Note Font Families::.

-mNAME'
Read in the file NAME.tmac'.  Normally groff' searches for this
in its macro directories.  If it isn't found, it tries tmac.NAME'
(searching in the same directories).

-nNUM'
Number the first page NUM.

-oLIST'
Output only pages in LIST, which is a comma-separated list of page
ranges; N' means print page N, M-N' means print every page
between M and N, -N' means print every page up to N, N-' means
print every page beginning with N.  gtroff' exits after printing
the last page in the list.  All the ranges are inclusive on both
ends.

Within gtroff', this information can be extracted with the .P'
register.  *Note Built-in Registers::.

If your document restarts page numbering at the beginning of each
chapter, then gtroff' prints the specified page range for each
chapter.

-rCN'
-rNAME=N'
Set number register C or NAME to the value N.  C must be a
one-letter name; NAME can be of arbitrary length.  N can be any
gtroff' numeric expression.  All register assignments happen

-FDIR'
Search DIR' for subdirectories devNAME' (NAME is the name of the
device), for the DESC' file, and for font files before looking in
the standard directories (*note Font Directories::).  This option
is passed to all pre- and postprocessors using the
GROFF_FONT_PATH' environment variable.

-MDIR'
Search directory DIR' for macro files before the standard
directories (*note Macro Directories::).

-IDIR'
This option may be used to specify a directory to search for files.
It is passed to the following programs:

* gsoelim' (see *Note gsoelim:: for more details); it also
implies groff''s -s' option.

* gtroff'; it is used to search files named in the psbb' and
so' requests.

* grops'; it is used to search files named in the
\X'ps: import' and \X'ps: file' escapes.

The current directory is always searched first. This option may be
specified more than once; the directories will be searched in the
order specified. No directory search is performed for files
specified using an absolute path.

File: groff,  Node: Environment,  Next: Macro Directories,  Prev: Groff Options,  Up: Invoking groff

2.2 Environment
===============

There are also several environment variables (of the operating system,
not within gtroff') which can modify the behavior of groff'.

GROFF_COMMAND_PREFIX'
If this is set to X, then groff' runs Xtroff' instead of
gtroff'.  This also applies to tbl', pic', eqn', grn',
refer', and soelim'.  It does not apply to grops', grodvi',
grotty', pre-grohtml', post-grohtml', grolj4', and gxditview'.

The default command prefix is determined during the installation
process.  If a non-GNU troff system is found, prefix g' is used,
none otherwise.

GROFF_TMAC_PATH'
A colon-separated list of directories in which to search for macro
files (before the default directories are tried).  *Note Macro
Directories::.

GROFF_TYPESETTER'
The default output device.

GROFF_FONT_PATH'
A colon-separated list of directories in which to search for the
dev'NAME directory (before the default directories are tried).
*Note Font Directories::.

GROFF_BIN_PATH'
This search path, followed by PATH', is used for commands executed
by groff'.

GROFF_TMPDIR'
The directory in which groff' creates temporary files.  If this is
not set and TMPDIR' is set, temporary files are created in that
directory.  Otherwise temporary files are created in a
system-dependent default directory (on Unix and GNU/Linux systems,
this is usually /tmp').  grops', grefer', pre-grohtml', and
post-grohtml' can create temporary files in this directory.

Note that MS-DOS and MS-Windows ports of groff' use semi-colons,
rather than colons, to separate the directories in the lists described
above.

File: groff,  Node: Macro Directories,  Next: Font Directories,  Prev: Environment,  Up: Invoking groff

2.3 Macro Directories
=====================

All macro file names must be named NAME.tmac' or tmac.NAME' to make
the -mNAME' command line option work.  The mso' request doesn't have
this restriction; any file name can be used, and gtroff' won't try to
append or prepend the tmac' string.

Macro files are kept in the "tmac directories", all of which
constitute the "tmac path".  The elements of the search path for macro
files are (in that order):

* The directories specified with gtroff''s or groff''s -M'
command line option.

* The directories given in the GROFF_TMAC_PATH' environment
variable.

* The current directory (only if in unsafe mode using the -U'
command line switch).

* The home directory.

* A platform-dependent directory, a site-specific
(platform-independent) directory, and the main tmac directory; the
default locations are

/usr/local/lib/groff/site-tmac
/usr/local/share/groff/site-tmac
/usr/local/share/groff/1.18.2/tmac

assuming that the version of groff' is 1.18.2, and the
installation prefix was /usr/local'.  It is possible to fine-tune
those directories during the installation process.

File: groff,  Node: Font Directories,  Next: Paper Size,  Prev: Macro Directories,  Up: Invoking groff

2.4 Font Directories
====================

Basically, there is no restriction how font files for groff' are named
and how long font names are; however, to make the font family mechanism
the family name, followed by the shape.  For example, the Times family
uses T' for the family name and R', B', I', and BI' to indicate
the shapes roman', bold', italic', and bold italic', respectively.
Thus the final font names are TR', TB', TI', and TBI'.

All font files are kept in the "font directories" which constitute
the "font path".  The file search functions will always append the
directory dev'NAME, where NAME is the name of the output device.
Assuming, say, DVI output, and /foo/bar' as a font directory, the font
files for grodvi' must be in /foo/bar/devdvi'.

The elements of the search path for font files are (in that order):

* The directories specified with gtroff''s or groff''s -F'
command line option.  All device drivers and some preprocessors
also have this option.

* The directories given in the GROFF_FONT_PATH' environment
variable.

* A site-specific directory and the main font directory; the default
locations are

/usr/local/share/groff/site-font
/usr/local/share/groff/1.18.2/font

assuming that the version of groff' is 1.18.2, and the
installation prefix was /usr/local'.  It is possible to fine-tune
those directories during the installation process.

File: groff,  Node: Paper Size,  Next: Invocation Examples,  Prev: Font Directories,  Up: Invoking groff

2.5 Paper Size
==============

In groff, the page size for gtroff' and for output devices are handled
separately.  *Note Page Layout::, for vertical manipulation of the page
size.  *Note Line Layout::, for horizontal changes.

A default paper size can be set in the device's DESC' file.  Most
output devices also have a command line option -p' to override the
default paper size and option -l' to use landscape orientation.  *Note
DESC File Format::, for a description of the papersize' keyword which
takes the same argument as -p'.

A convenient shorthand to set a particular paper size for gtroff'
is command line option -dpaper=SIZE'.  This defines string paper'
which is processed in file papersize.tmac' (loaded in the start-up
file troffrc' by default).  Possible values for SIZE are the same as
the predefined values for the papersize' keyword (but only in
lowercase) except a7'-d7'.  An appended l' (ell) character denotes
landscape orientation.

For example, use the following for PS output on A4 paper in landscape
orientation:

groff -Tps -dpaper=a4l -P-pa4 -P-l -ms foo.ms > foo.ps

Note that it is up to the particular macro package to respect default
page dimensions set in this way (most do).

File: groff,  Node: Invocation Examples,  Prev: Paper Size,  Up: Invoking groff

2.6 Invocation Examples
=======================

This section lists several common uses of groff' and the corresponding
command lines.

groff file

This command processes file' without a macro package or a
preprocessor.  The output device is the default, ps', and the output
is sent to stdout'.

groff -t -mandoc -Tascii file | less

This is basically what a call to the man' program does.  gtroff'
processes the manual page file' with the mandoc' macro file (which in
turn either calls the man' or the mdoc' macro package), using the
tbl' preprocessor and the ASCII output device.  Finally, the less'
pager displays the result.

groff -X -m me file

Preview file' with gxditview', using the me' macro package.  Since
no -T' option is specified, use the default device (ps').  Note that
you can either say -m me' or -me'; the latter is an anachronism from
the early days of UNIX.(1) (*note Invocation Examples-Footnote-1::)

groff -man -rD1 -z file

Check file' with the man' macro package, forcing double-sided
printing - don't produce any output.

* grog::

File: groff,  Node: Invocation Examples-Footnotes,  Up: Invocation Examples

(1) The same is true for the other main macro packages that come
with groff': man', mdoc', ms', mm', and mandoc'.  This won't work
in general; for example, to load trace.tmac', either -mtrace' or
-m trace' must be used.

File: groff,  Node: grog,  Prev: Invocation Examples,  Up: Invocation Examples

2.6.1 grog'
------------

grog' reads files, guesses which of the groff' preprocessors and/or
macro packages are required for formatting them, and prints the groff'
command including those options on the standard output.  It generates
one or more of the options -e', -man', -me', -mm', -mom', -ms',
-mdoc', -mdoc-old', -p', -R', -g', -G', -s', and -t'.

A special file name -' refers to the standard input.  Specifying no
files also means to read the standard input.  Any specified options are
included in the printed command.  No space is allowed between options
and their arguments.  The only options recognized are -C' (which is
also passed on) to enable compatibility mode, and -v' to print the
version number and exit.

For example,

grog -Tdvi paper.ms

guesses the appropriate command to print paper.ms' and then prints it
to the command line after adding the -Tdvi' option.  For direct
execution, enclose the call to grog' in backquotes at the UNIX shell
prompt:

grog -Tdvi paper.ms > paper.dvi

As seen in the example, it is still necessary to redirect the output to
something meaningful (i.e. either a file or a pager program like
less').

File: groff,  Node: Tutorial for Macro Users,  Next: Macro Packages,  Prev: Invoking groff,  Up: Top

3 Tutorial for Macro Users
**************************

Most users tend to use a macro package to format their papers.  This
means that the whole breadth of groff' is not necessary for most
people.  This chapter covers the material needed to efficiently use a
macro package.

* Basics::
* Common Features::

File: groff,  Node: Basics,  Next: Common Features,  Prev: Tutorial for Macro Users,  Up: Tutorial for Macro Users

3.1 Basics
==========

This section covers some of the basic concepts necessary to understand
how to use a macro package.(1) (*note Basics-Footnote-1::) References
are made throughout to more detailed information, if desired.

gtroff' reads an input file prepared by the user and outputs a
formatted document suitable for publication or framing.  The input
consists of text, or words to be printed, and embedded commands
("requests" and "escapes"), which tell gtroff' how to format the
output.  For more detail on this, see *Note Embedded Commands::.

The word "argument" is used in this chapter to mean a word or number
which appears on the same line as a request, and which modifies the
meaning of that request.  For example, the request

.sp

spaces one line, but

.sp 4

spaces four lines.  The number 4 is an argument to the sp' request
which says to space four lines instead of one.  Arguments are separated
from the request and from each other by spaces (_no_ tabs).  More
details on this can be found in *Note Request and Macro Arguments::.

The primary function of gtroff' is to collect words from input
lines, fill output lines with those words, justify the right-hand margin
by inserting extra spaces in the line, and output the result.  For
example, the input:

Now is the time
for all good men
to come to the aid
of their party.
Four score and seven
years ago, etc.

is read, packed onto output lines, and justified to produce:

Now is the time for all good men to come to the aid of their party.
Four score and seven years ago, etc.

Sometimes a new output line should be started even though the current
line is not yet full; for example, at the end of a paragraph.  To do
this it is possible to cause a "break", which starts a new output line.
Some requests cause a break automatically, as normally do blank input
lines and input lines beginning with a space.

Not all input lines are text to be formatted.  Some input lines are
requests which describe how to format the text.  Requests always have a
period (.') or an apostrophe ('') as the first character of the input
line.

The text formatter also does more complex things, such as
automatically numbering pages, skipping over page boundaries, putting
footnotes in the correct place, and so forth.

Here are a few hints for preparing text for input to gtroff'.

* First, keep the input lines short.  Short input lines are easier to
edit, and gtroff' packs words onto longer lines anyhow.

* In keeping with this, it is helpful to begin a new line after every
comma or phrase, since common corrections are to add or delete
sentences or phrases.

* End each sentence with two spaces - or better, start each sentence
on a new line.  gtroff' recognizes characters that usually end a
sentence, and inserts sentence space accordingly.

* Do not hyphenate words at the end of lines - gtroff' is smart
enough to hyphenate words as needed, but is not smart enough to
take hyphens out and join a word back together.  Also, words such
as "mother-in-law" should not be broken over a line, since then a
space can occur where not wanted, such as "mother- in-law".

gtroff' double-spaces output text automatically if you use the
request .ls 2'.  Reactivate single-spaced mode by typing .ls 1'.(2)
(*note Basics-Footnote-2::)

A number of requests allow to change the way the output looks,
sometimes called the "layout" of the output page.  Most of these
requests adjust the placing of "whitespace" (blank lines or spaces).

The bp' request starts a new page, causing a line break.

The request .sp N' leaves N lines of blank space.  N can be omitted
(meaning skip a single line) or can be of the form Ni (for N inches) or
Nc (for N centimeters).  For example, the input:

.sp 1.5i
My thoughts on the subject
.sp

leaves one and a half inches of space, followed by the line "My
thoughts on the subject", followed by a single blank line (more
measurement units are available, see *Note Measurements::).

Text lines can be centered by using the ce' request.  The line
after ce' is centered (horizontally) on the page.  To center more than
one line, use .ce N' (where N is the number of lines to center),
followed by the N lines.  To center many lines without counting them,
type:

.ce 1000
lines to center
.ce 0

The .ce 0' request tells groff' to center zero more lines, in other
words, stop centering.

All of these requests cause a break; that is, they always start a new
line.  To start a new line without performing any other action, use
br'.

File: groff,  Node: Basics-Footnotes,  Up: Basics

(1) This section is derived from Writing Papers with nroff using
-me' by Eric P. Allman.

(2) If you need finer granularity of the vertical space, use the
pvs' request (*note Changing Type Sizes::).

File: groff,  Node: Common Features,  Prev: Basics,  Up: Tutorial for Macro Users

3.2 Common Features
===================

gtroff' provides very low-level operations for formatting a document.
There are many common routine operations which are done in all
documents.  These common operations are written into "macros" and
collected into a "macro package".

All macro packages provide certain common capabilities which fall
into the following categories.

* Paragraphs::
* Sections and Chapters::
* Displays::
* Footnotes and Annotations::
* Indices::
* Paper Formats::
* Multiple Columns::
* Font and Size Changes::
* Predefined Strings::
* Preprocessor Support::
* Configuration and Customization::

File: groff,  Node: Paragraphs,  Next: Sections and Chapters,  Prev: Common Features,  Up: Common Features

3.2.1 Paragraphs
----------------

One of the most common and most used capability is starting a
paragraph.  There are a number of different types of paragraphs, any of
which can be initiated with macros supplied by the macro package.
indented, like the text in this manual.  There are also block style
paragraphs, which omit the indentation:

Some   men  look   at  constitutions   with  sanctimonious
reverence, and deem them like the ark of the covenant, too
sacred to be touched.

And there are also indented paragraphs which begin with a tag or label
at the margin and the remaining text indented.

one   This is  the first paragraph.  Notice  how the first
line of  the resulting  paragraph lines up  with the
other lines in the paragraph.

longlabel
This  paragraph   had  a  long   label.   The  first
character of text on the first line does not line up
with  the  text  on  second  and  subsequent  lines,
although they line up with each other.

A variation of this is a bulleted list.

to use other glyphs instead of the bullet.  In nroff
mode using the ASCII character set for output, a dot
is used instead of a real bullet.

File: groff,  Node: Sections and Chapters,  Next: Headers and Footers,  Prev: Paragraphs,  Up: Common Features

3.2.2 Sections and Chapters
---------------------------

Most macro packages supply some form of section headers.  The simplest
kind is simply the heading on a line by itself in bold type.  Others
styles at different levels.  Some, more sophisticated, macro packages
supply macros for starting chapters and appendices.

File: groff,  Node: Headers and Footers,  Next: Page Layout Adjustment,  Prev: Sections and Chapters,  Up: Common Features

-------------------------

Every macro package gives some way to manipulate the "headers" and
"footers" (also called "titles") on each page.  This is text put at the
top and bottom of each page, respectively, which contain data like the
current page number, the current chapter title, and so on.  Its
appearance is not affected by the running text.  Some packages allow
for different ones on the even and odd pages (for material printed in a
book form).

The titles are called "three-part titles", that is, there is a
left-justified part, a centered part, and a right-justified part.  An
automatically generated page number may be put in any of these fields
with the %' character (see *Note Page Layout::, for more details).

File: groff,  Node: Page Layout Adjustment,  Next: Displays,  Prev: Headers and Footers,  Up: Common Features

3.2.4 Page Layout
-----------------

Most macro packages let the user specify top and bottom margins and
other details about the appearance of the printed pages.

File: groff,  Node: Displays,  Next: Footnotes and Annotations,  Prev: Page Layout Adjustment,  Up: Common Features

3.2.5 Displays
--------------

"Displays" are sections of text to be set off from the body of the
paper.  Major quotes, tables, and figures are types of displays, as are
all the examples used in this document.

"Major quotes" are quotes which are several lines long, and hence
are set in from the rest of the text without quote marks around them.

A "list" is an indented, single-spaced, unfilled display.  Lists
should be used when the material to be printed should not be filled and
justified like normal text, such as columns of figures or the examples
used in this paper.

A "keep" is a display of lines which are kept on a single page if
possible.  An example for a keep might be a diagram.  Keeps differ from
lists in that lists may be broken over a page boundary whereas keeps are
not.

"Floating keeps" move relative to the text.  Hence, they are good for
things which are referred to by name, such as "See figure 3".  A
floating keep appears at the bottom of the current page if it fits;
otherwise, it appears at the top of the next page.  Meanwhile, the
surrounding text flows' around the keep, thus leaving no blank areas.

3.2.6 Footnotes and Annotations
-------------------------------

There are a number of requests to save text for later printing.

"Footnotes" are printed at the bottom of the current page.

"Delayed text" is very similar to a footnote except that it is
printed when called for explicitly.  This allows a list of references to
appear (for example) at the end of each chapter, as is the convention in
some disciplines.

Most macro packages which supply this functionality also supply a
means of automatically numbering either type of annotation.

-----------------------

"Tables of contents" are a type of delayed text having a tag (usually
the page number) attached to each entry after a row of dots.  The table
accumulates throughout the paper until printed, usually after the paper
has ended.  Many macro packages provide the ability to have several
tables, etc).

3.2.8 Indices
-------------

While some macro packages use the term "index", none actually provide
that functionality.  The facilities they call indices are actually more
appropriate for tables of contents.

To produce a real index in a document, external tools like the
makeindex' program are necessary.

File: groff,  Node: Paper Formats,  Next: Multiple Columns,  Prev: Indices,  Up: Common Features

3.2.9 Paper Formats
-------------------

Some macro packages provide stock formats for various kinds of
documents.  Many of them provide a common format for the title and
opening pages of a technical paper.  The mm' macros in particular
provide formats for letters and memoranda.

File: groff,  Node: Multiple Columns,  Next: Font and Size Changes,  Prev: Paper Formats,  Up: Common Features

3.2.10 Multiple Columns
-----------------------

Some macro packages (but not man') provide the ability to have two or
more columns on a page.

File: groff,  Node: Font and Size Changes,  Next: Predefined Strings,  Prev: Multiple Columns,  Up: Common Features

3.2.11 Font and Size Changes
----------------------------

The built-in font and size functions are not always intuitive, so all
macro packages provide macros to make these operations simpler.

File: groff,  Node: Predefined Strings,  Next: Preprocessor Support,  Prev: Font and Size Changes,  Up: Common Features

3.2.12 Predefined Strings
-------------------------

Most macro packages provide various predefined strings for a variety of
uses; examples are sub- and superscripts, printable dates, quotes and
various special characters.

File: groff,  Node: Preprocessor Support,  Next: Configuration and Customization,  Prev: Predefined Strings,  Up: Common Features

3.2.13 Preprocessor Support
---------------------------

All macro packages provide support for various preprocessors and may
extend their functionality.

For example, all macro packages mark tables (which are processed with
gtbl') by placing them between TS' and TE' macros.  The ms' macro
package has an option, .TS H', that prints a caption at the top of a
new page (when the table is too long to fit on a single page).

File: groff,  Node: Configuration and Customization,  Prev: Preprocessor Support,  Up: Common Features

3.2.14 Configuration and Customization
--------------------------------------

Some macro packages provide means of customizing many of the details of
how the package behaves.  This ranges from setting the default type size
to changing the appearance of section headers.

File: groff,  Node: Macro Packages,  Next: gtroff Reference,  Prev: Tutorial for Macro Users,  Up: Top

4 Macro Packages
****************

This chapter documents the main macro packages that come with groff'.

Different main macro packages can't be used at the same time; for
example

groff -m man foo.man -m ms bar.doc

doesn't work.  Note that option arguments are processed before
non-option arguments; the above (failing) sample is thus reordered to

groff -m man -m ms foo.man bar.doc

* man::
* mdoc::
* ms::
* me::
* mm::

File: groff,  Node: man,  Next: mdoc,  Prev: Macro Packages,  Up: Macro Packages

4.1 man'
=========

This is the most popular and probably the most important macro package
of groff'.  It is easy to use, and a vast majority of manual pages are
based on it.

* Man options::
* Man usage::
* Man font macros::
* Miscellaneous man macros::
* Predefined man strings::
* Preprocessors in man pages::
* Optional man extensions::

File: groff,  Node: Man options,  Next: Man usage,  Prev: man,  Up: man

4.1.1 Options
-------------

The command line format for using the man' macros with groff' is:

groff -m man [ -rLL=LENGTH ] [ -rLT=LENGTH ] [ -rFT=DIST ]
[ -rcR=1 ] [ -rC1 ] [ -rD1 ] [-rHY=FLAGS ]
[ -rPNNN ] [ -rSXX ] [ -rXNNN ]
[ -rIN=LENGTH ] [ -rSN=LENGTH ] [ FILES... ]

It is possible to use -man' instead of -m man'.

-rcR=1'
This option (the default if a TTY output device is used) creates a
single, very long page instead of multiple pages.  Use -rcR=0' to
disable it.

-rC1'
If more than one manual page is given on the command line, number
the pages continuously, rather than starting each at 1.

-rD1'
Double-sided printing.  Footers for even and odd pages are
formatted differently.

-rFT=DIST'
Set the position of the footer text to DIST.  If positive, the
distance is measured relative to the top of the page, otherwise it
is relative to the bottom.  The default is -0.5i.

-rHY=FLAGS'
Set hyphenation flags.  Possible values are 1 to hyphenate without
restrictions, 2  to not hyphenate the last word on a page, 4 to
not hyphenate the last two characters of a word, and 8 to not
hyphenate the first two characters of a word.  These values are

-rIN=LENGTH'
Set the body text indentation to LENGTH.  If not specified, the
indentation defaults to 7n (7 characters) in nroff mode and 7.2n
otherwise.  For nroff, this value should always be an integer
multiple of unit n' to get consistent indentation.

-rLL=LENGTH'
Set line length to LENGTH.  If not specified, the line length is
set to respect any value set by a prior ll' request (which _must_
be in effect when the TH' macro is invoked), if this differs from
the built-in default for the formatter; otherwise it defaults to
78n in nroff mode (this is 78 characters per line) and 6.5i in
troff mode.(1) (*note Man options-Footnote-1::)

-rLT=LENGTH'
Set title length to LENGTH.  If not specified, the title length
defaults to the line length.

-rPNNN'
Page numbering starts with NNN rather than with 1.

-rSXX'
Use XX (which can be 10, 11, or 12pt) as the base document font
size instead of the default value of 10pt.

-rSN=LENGTH'
Set the indentation for sub-subheadings to LENGTH.  If not
specified, the indentation defaults to 3n.

-rXNNN'
After page NNN, number pages as NNNa, NNNb, NNNc, etc.  For
example, the option -rX2' produces the following page numbers: 1,
2, 2a, 2b, 2c, etc.

File: groff,  Node: Man options-Footnotes,  Up: Man options

(1) Note that the use of a .ll LENGTH' request to initialize the
line length, prior to use of the TH' macro, is supported for backward
compatibility with some versions of the man' program.  _Always_ use the
-rLL=LENGTH' option, or an equivalent .nr LL LENGTH' request, in
preference to such a .ll LENGTH' request.  In particular, note that in
nroff mode, the request .ll 65n', (with any LENGTH expression which
evaluates equal to 65n, i.e., the formatter's default line length in
nroff mode), will _not_ set the line length to 65n (it will be adjusted
to the man' macro package's default setting of 78n), whereas the use
of the -rLL=65n' option, or the .nr LL 65n' request _will_ establish
a line length of 65n.

File: groff,  Node: Man usage,  Next: Man font macros,  Prev: Man options,  Up: man

4.1.2 Usage
-----------

This section describes the available macros for manual pages.  For
further customization, put additional macros and requests into the file
man.local' which is loaded immediately after the man' package.

-- Macro: .TH title section [extra1 [extra2 [extra3]]]
Set the title of the man page to TITLE and the section to SECTION,
which must have a value between 1 and 8.  The value of SECTION may
also have a string appended, e.g. .pm', to indicate a specific
subsection of the man pages.

Both TITLE and SECTION are positioned at the left and right in the
header line (with SECTION in parentheses immediately appended to
TITLE.  EXTRA1 is positioned in the middle of the footer line.
EXTRA2 is positioned at the left in the footer line (or at the
left on even pages and at the right on odd pages if double-sided
printing is active).  EXTRA3 is centered in the header line.

For HTML output, headers and footers are completely suppressed.

Additionally, this macro starts a new page; the new line number
is 1 again (except if the -rC1' option is given on the command
line) - this feature is intended only for formatting multiple man
pages; a single man page should contain exactly one TH' macro at
the beginning of the file.

Set up an unnumbered section heading sticking out to the left.
Prints out all the text following SH' up to the end of the line
(or the text in the next line if there is no argument to SH') in
bold face (or the font specified by the string HF'), one size
larger than the base document size.  Additionally, the left margin
and the indentation for the following text is reset to its default
value.

Set up an unnumbered (sub)section heading.  Prints out all the text
following SS' up to the end of the line (or the text in the next
line if there is no argument to SS') in bold face (or the font
specified by the string HF'), at the same size as the base
document size.  Additionally, the left margin and the indentation
for the following text is reset to its default value.

-- Macro: .TP [nnn]
Set up an indented paragraph with label.  The indentation is set to
NNN if that argument is supplied (the default unit is n' if
omitted), otherwise it is set to the previous indentation value
specified with TP', IP', or HP' (or to the default value if
none of them have been used yet).

The first line of text following this macro is interpreted as a
string to be printed flush-left, as it is appropriate for a label.
It is not interpreted as part of a paragraph, so there is no
attempt to fill the first line with text from the following input
lines.  Nevertheless, if the label is not as wide as the
indentation the paragraph starts at the same line (but indented),
continuing on the following lines.  If the label is wider than the
indentation the descriptive part of the paragraph begins on the
line following the label, entirely indented.  Note that neither
font shape nor font size of the label is set to a default value;
on the other hand, the rest of the text has default font settings.

-- Macro: .LP
-- Macro: .PP
-- Macro: .P
These macros are mutual aliases.  Any of them causes a line break
at the current position, followed by a vertical space downwards by
the amount specified by the PD' macro.  The font size and shape
are reset to the default value (10pt roman if no -rS' option is
given on the command line).  Finally, the current left margin and
the indentation is restored.

-- Macro: .IP [designator [nnn]]
Set up an indented paragraph, using DESIGNATOR as a tag to mark
its beginning.  The indentation is set to NNN if that argument is
supplied (default unit is n'), otherwise it is set to the
previous indentation value specified with TP', IP', or HP' (or
the default value if none of them have been used yet).  Font size
and face of the paragraph (but not the designator) are reset to
their default values.

To start an indented paragraph with a particular indentation but
without a designator, use ""' (two double quotes) as the first
argument of IP'.

For example, to start a paragraph with bullets as the designator
and 4 en indentation, write

.IP bu 4 -- Macro: .HP [nnn] Set up a paragraph with hanging left indentation. The indentation is set to NNN if that argument is supplied (default unit is n'), otherwise it is set to the previous indentation value specified with TP', IP', or HP' (or the default value if non of them have been used yet). Font size and face are reset to their default values. -- Macro: .RS [nnn] Move the left margin to the right by the value NNN if specified (default unit is n'); otherwise it is set to the previous indentation value specified with TP', IP', or HP' (or to the default value if none of them have been used yet). The indentation value is then set to the default. Calls to the RS' macro can be nested. -- Macro: .RE [nnn] Move the left margin back to level NNN, restoring the previous left margin. If no argument is given, it moves one level back. The first level (i.e., no call to RS' yet) has number 1, and each call to RS' increases the level by 1. To summarize, the following macros cause a line break with the insertion of vertical space (which amount can be changed with the PD' macro): SH', SS', TP', LP' (PP', P'), IP', and HP'. The macros RS' and RE' also cause a break but do not insert vertical space. Finally, the macros SH', SS', LP' (PP', P'), and RS' reset the indentation to its default value. File: groff, Node: Man font macros, Next: Miscellaneous man macros, Prev: Man usage, Up: man 4.1.3 Macros to set fonts ------------------------- The standard font is roman; the default text size is 10 point. If command line option -rS=N' is given, use Npt as the default text size. -- Macro: .SM [text] Set the text on the same line or the text on the next line in a font that is one point size smaller than the default font. -- Macro: .SB [text] Set the text on the same line or the text on the next line in bold face font, one point size smaller than the default font. -- Macro: .BI text Set its arguments alternately in bold face and italic, without a space between the arguments. Thus, .BI this "word and" that produces "thisword andthat" with "this" and "that" in bold face, and "word and" in italics. -- Macro: .IB text Set its arguments alternately in italic and bold face, without a space between the arguments. -- Macro: .RI text Set its arguments alternately in roman and italic, without a space between the arguments. -- Macro: .IR text Set its arguments alternately in italic and roman, without a space between the arguments. -- Macro: .BR text Set its arguments alternately in bold face and roman, without a space between the arguments. -- Macro: .RB text Set its arguments alternately in roman and bold face, without a space between the arguments. -- Macro: .B [text] Set TEXT in bold face. If no text is present on the line where the macro is called, then the text of the next line appears in bold face. -- Macro: .I [text] Set TEXT in italic. If no text is present on the line where the macro is called, then the text of the next line appears in italic. File: groff, Node: Miscellaneous man macros, Next: Predefined man strings, Prev: Man font macros, Up: man 4.1.4 Miscellaneous macros -------------------------- The default indentation is 7.2n in troff mode and 7n in nroff mode except for grohtml' which ignores indentation. -- Macro: .DT Set tabs every 0.5 inches. Since this macro is always executed during a call to the TH' macro, it makes sense to call it only if the tab positions have been changed. -- Macro: .PD [nnn] Adjust the empty space before a new paragraph (or section). The optional argument gives the amount of space (default unit is v'); without parameter, the value is reset to its default value (1 line in nroff mode, 0.4v otherwise). This affects the macros SH', SS', TP', LP' (as well as PP' and P'), IP', and HP'. The following two macros are included for BSD compatibility. -- Macro: .AT [system [release]] Alter the footer for use with AT&T manpages. This command exists only for compatibility; don't use it. The first argument SYSTEM can be: 3' 7th Edition (the default) 4' System III 5' System V An optional second argument RELEASE to AT' specifies the release number (such as "System V Release 3"). -- Macro: .UC [version] Alters the footer for use with BSD manpages. This command exists only for compatibility; don't use it. The argument can be: 3' 3rd Berkeley Distribution (the default) 4' 4th Berkeley Distribution 5' 4.2 Berkeley Distribution 6' 4.3 Berkeley Distribution 7' 4.4 Berkeley Distribution File: groff, Node: Predefined man strings, Next: Preprocessors in man pages, Prev: Miscellaneous man macros, Up: man 4.1.5 Predefined strings ------------------------ The following strings are defined: -- String: \*[S] Switch back to the default font size. -- String: \*[HF] The typeface used for headings. The default is B'. -- String: \*[R] The registered' sign. -- String: \*[Tm] The trademark' sign. -- String: \*[lq] -- String: \*[rq] Left and right quote. This is equal to \(lq' and \(rq', respectively. File: groff, Node: Preprocessors in man pages, Next: Optional man extensions, Prev: Predefined man strings, Up: man 4.1.6 Preprocessors in man' pages ---------------------------------- If a preprocessor like gtbl' or geqn' is needed, it has become common usage to make the first line of the man page look like this: '\" WORD Note the single space character after the double quote. WORD consists of letters for the needed preprocessors: e' for geqn', r' for grefer', t' for gtbl'. Modern implementations of the man' program read this first line and automatically call the right preprocessor(s). File: groff, Node: Optional man extensions, Prev: Preprocessors in man pages, Up: man 4.1.7 Optional man' extensions ------------------------------- Use the file man.local' for local extensions to the man' macros or for style changes. Custom headers and footers .......................... In groff versions 1.18.2 and later, you can specify custom headers and footers by redefining the following macros in man.local'. -- Macro: .PT Control the content of the headers. Normally, the header prints the command name and section number on either side, and the optional fifth argument to TH' in the center. -- Macro: .BT Control the content of the footers. Normally, the footer prints the page number and the third and fourth arguments to TH'. Use the FT' number register to specify the footer position. The default is -0.5i. Ultrix-specific man macros .......................... The groff' source distribution includes a file named man.ultrix', containing macros compatible with the Ultrix variant of man'. Copy this file into man.local' (or use the mso' request to load it) to enable the following macros. -- Macro: .CT key Print <CTRL/KEY>'. -- Macro: .CW Print subsequent text using the constant width (Courier) typeface. -- Macro: .Ds Begin a non-filled display. -- Macro: .De End a non-filled display started with Ds'. -- Macro: .EX [indent] Begins a non-filled display using the constant width (Courier) typeface. Use the optional INDENT argument to indent the display. -- Macro: .EE End a non-filled display started with EX'. -- Macro: .G [text] Sets TEXT in Helvetica. If no text is present on the line where the macro is called, then the text of the next line appears in Helvetica. -- Macro: .GL [text] Sets TEXT in Helvetica Oblique. If no text is present on the line where the macro is called, then the text of the next line appears in Helvetica Oblique. -- Macro: .HB [text] Sets TEXT in Helvetica Bold. If no text is present on the line where the macro is called, then all text up to the next HB' appears in Helvetica Bold. -- Macro: .TB [text] Identical to HB'. -- Macro: .MS title sect [punct] Set a manpage reference in Ultrix format. The TITLE is in Courier instead of italic. Optional punctuation follows the section number without an intervening space. -- Macro: .NT [C'] [title] Begin a note. Print the optional title, or the word "Note", centered on the page. Text following the macro makes up the body of the note, and is indented on both sides. If the first argument is C', the body of the note is printed centered (the second argument replaces the word "Note" if specified). -- Macro: .NE End a note begun with NT'. -- Macro: .PN path [punct] Set the path name in constant width (Courier), followed by optional punctuation. -- Macro: .Pn [punct] path [punct] When called with two arguments, identical to PN'. When called with three arguments, set the second argument in constant width (Courier), bracketed by the first and third arguments in the current font. -- Macro: .R Switch to roman font and turn off any underlining in effect. -- Macro: .RN Print the string <RETURN>'. -- Macro: .VS [4'] Start printing a change bar in the margin if the number 4' is specified. Otherwise, this macro does nothing. -- Macro: .VE End printing the change bar begun by VS'. Simple example .............. The following example man.local' file alters the SH' macro to add some extra vertical space before printing the heading. Headings are printed in Helvetica Bold. .\" Make the heading fonts Helvetica .ds HF HB . .\" Put more whitespace in front of headings. .rn SH SH-orig .de SH . if t .sp (u;\\n[PD]*2) . SH-orig \\* .. File: groff, Node: mdoc, Next: ms, Prev: man, Up: Macro Packages 4.2 mdoc' ========== See the groff_mdoc(7)' man page (type man groff_mdoc' at the command line). File: groff, Node: ms, Next: me, Prev: mdoc, Up: Macro Packages 4.3 ms' ======== The -ms' macros are suitable for reports, letters, books, user manuals, and so forth. The package provides macros for cover pages, section headings, paragraphs, lists, footnotes, pagination, and a table of contents. * Menu: * ms Intro:: * General ms Structure:: * ms Document Control Registers:: * ms Cover Page Macros:: * ms Body Text:: * ms Page Layout:: * Differences from AT&T ms:: * Naming Conventions:: File: groff, Node: ms Intro, Next: General ms Structure, Prev: ms, Up: ms 4.3.1 Introduction to ms' -------------------------- The original -ms' macros were included with AT&T troff' as well as the man' macros. While the man' package is intended for brief documents that can be read on-line as well as printed, the ms' macros are suitable for longer documents that are meant to be printed rather than read on-line. The ms' macro package included with groff' is a complete, bottom-up re-implementation. Several macros (specific to AT&T or Berkeley) are not included, while several new commands are. *Note Differences from AT&T ms::, for more information. File: groff, Node: General ms Structure, Next: ms Document Control Registers, Prev: ms Intro, Up: ms 4.3.2 General structure of an ms' document ------------------------------------------- The ms' macro package expects a certain amount of structure, but not as much as packages such as man' or mdoc'. The simplest documents can begin with a paragraph macro (such as LP' or PP'), and consist of text separated by paragraph macros or even blank lines. Longer documents have a structure as follows: *Document type* If you invoke the RP' (report) macro on the first line of the document, groff' prints the cover page information on its own page; otherwise it prints the information on the first page with your document text immediately following. Other document formats found in AT&T troff' are specific to AT&T or Berkeley, and are not supported in groff'. *Format and layout* By setting number registers, you can change your document's type (font and size), margins, spacing, headers and footers, and footnotes. *Note ms Document Control Registers::, for more details. *Cover page* A cover page consists of a title, the author's name and institution, an abstract, and the date.(1) (*note General ms Structure-Footnote-1::) *Note ms Cover Page Macros::, for more details. *Body* Following the cover page is your document. You can use the ms' macros to write reports, letters, books, and so forth. The package is designed for structured documents, consisting of paragraphs interspersed with headings and augmented by lists, footnotes, tables, and other common constructs. *Note ms Body Text::, for more details. *Table of contents* Longer documents usually include a table of contents, which you can invoke by placing the TC' macro at the end of your document. The ms' macros have minimal indexing facilities, consisting of the IX' macro, which prints an entry on standard error. Printing the table of contents at the end is necessary since groff' is a single-pass text formatter, thus it cannot determine the page number of each section until that section has actually been set and printed. Since ms' output is intended for hardcopy, you can manually relocate the pages containing the table of contents between the cover page and the body text after printing. File: groff, Node: General ms Structure-Footnotes, Up: General ms Structure (1) Actually, only the title is required. File: groff, Node: ms Document Control Registers, Next: ms Cover Page Macros, Prev: General ms Structure, Up: ms 4.3.3 Document control registers -------------------------------- The following is a list of document control number registers. For the sake of consistency, set registers related to margins at the beginning of your document, or just after the RP' macro. You can set other registers later in your document, but you should keep them together at the beginning to make them easy to find and edit as necessary. Margin Settings ............... -- Register: \n[PO] Defines the page offset (i.e., the left margin). There is no explicit right margin setting; the combination of the PO' and LL' registers implicitly define the right margin width. Effective: next page. Default value: 1i. -- Register: \n[LL] Defines the line length (i.e., the width of the body text). Effective: next paragraph. Default: 6i. -- Register: \n[LT] Defines the title length (i.e., the header and footer width). This is usually the same as LL', but not necessarily. Effective: next paragraph. Default: 6i. -- Register: \n[HM] Defines the header margin height at the top of the page. Effective: next page. Default: 1i. -- Register: \n[FM] Defines the footer margin height at the bottom of the page. Effective: next page. Default: 1i. Text Settings ............. -- Register: \n[PS] Defines the point size of the body text. If the value is larger than or equal to 1000, divide it by 1000 to get a fractional point size. For example, .nr PS 10250' sets the document's point size to 10.25p. Effective: next paragraph. Default: 10p. -- Register: \n[VS] Defines the space between lines (line height plus leading). If the value is larger than or equal to 1000, divide it by 1000 to get a fractional point size. Due to backwards compatibility, VS' must be smaller than 40000 (this is 40.0p). Effective: next paragraph. Default: 12p. -- Register: \n[PSINCR] Defines an increment in point size, which will be applied to section headings at nesting levels below the value specified in GROWPS'. The value of PSINCR' should be specified in points, with the p scaling factor, and may include a fractional component; for example, .nr PSINCR 1.5p' sets a point size increment of 1.5p. Effective: next section heading. Default: 1p. -- Register: \n[GROWPS] Defines the heading level below which the point size increment set by PSINCR' becomes effective. Section headings at and above the level specified by GROWPS' will be printed at the point size set by PS'; for each level below the value of GROWPS', the point size will be increased in steps equal to the value of PSINCR'. Setting GROWPS' to any value less than 2 disables the incremental heading size feature. Effective: next section heading. Default: 0. -- Register: \n[HY] Defines the hyphenation level. HY' sets safely the value of the low-level hy' register. Setting the value of HY' to 0 is equivalent to using the nh' request. Effective: next paragraph. Default: 14. -- Register: \n[FAM] Defines the font family used to typeset the document. Effective: next paragraph. Default: as defined in the output device. Paragraph Settings .................. -- Register: \n[PI] Defines the initial indentation of a (PP' macro) paragraph. Effective: next paragraph. Default: 5n. -- Register: \n[PD] Defines the space between paragraphs. Effective: next paragraph. Default: 0.3v. -- Register: \n[QI] Defines the indentation on both sides of a quoted (QP' macro) paragraph. Effective: next paragraph. Default: 5n. -- Register: \n[PORPHANS] Defines the minimum number of initial lines of any paragraph which should be kept together, to avoid orphan lines at the bottom of a page. If a new paragraph is started close to the bottom of a page, and there is insufficient space to accommodate PORPHANS' lines before an automatic page break, then the page break will be forced, before the start of the paragraph. Effective: next paragraph. Default: 1. -- Register: \n[HORPHANS] Defines the minimum number of lines of the following paragraph which should be kept together with any section heading introduced by the NH' or SH' macros. If a section heading is placed close to the bottom of a page, and there is insufficient space to accommodate both the heading and at least HORPHANS' lines of the following paragraph, before an automatic page break, then the page break will be forced before the heading. Effective: next paragraph. Default: 1. Footnote Settings ................. -- Register: \n[FL] Defines the length of a footnote. Effective: next footnote. Default: \n[LL]' * 5 / 6. -- Register: \n[FI] Defines the footnote indentation. Effective: next footnote. Default: 2n. -- Register: \n[FF] The footnote format: 0' Print the footnote number as a superscript; indent the footnote (default). 1' Print the number followed by a period (like 1.) and indent the footnote. 2' Like 1, without an indentation. 3' Like 1, but print the footnote number as a hanging paragraph. Effective: next footnote. Default: 0. -- Register: \n[FPS] Defines the footnote point size. If the value is larger than or equal to 1000, divide it by 1000 to get a fractional point size. Effective: next footnote. Default: \n[PS]' - 2. -- Register: \n[FVS] Defines the footnote vertical spacing. If the value is larger than or equal to 1000, divide it by 1000 to get a fractional point size. Effective: next footnote. Default: \n[FPS]' + 2. -- Register: \n[FPD] Defines the footnote paragraph spacing. Effective: next footnote. Default: \n[PD]' / 2. Miscellaneous Number Registers .............................. -- Register: \n[MINGW] Defines the minimum width between columns in a multi-column document. Effective: next page. Default: 2n. File: groff, Node: ms Cover Page Macros, Next: ms Body Text, Prev: ms Document Control Registers, Up: ms 4.3.4 Cover page macros ----------------------- Use the following macros to create a cover page for your document in the order shown. -- Macro: .RP [no'] Specifies the report format for your document. The report format creates a separate cover page. The default action (no RP' macro) is to print a subset of the cover page on page 1 of your document. If you use the word no' as an optional argument, groff' prints a title page but does not repeat any of the title page information (title, author, abstract, etc.) on page 1 of the document. -- Macro: .P1 (P-one) Prints the header on page 1. The default is to suppress the header. -- Macro: .DA [...] (optional) Prints the current date, or the arguments to the macro if any, on the title page (if specified) and in the footers. This is the default for nroff'. -- Macro: .ND [...] (optional) Prints the current date, or the arguments to the macro if any, on the title page (if specified) but not in the footers. This is the default for troff'. -- Macro: .TL Specifies the document title. groff' collects text following the TL' macro into the title, until reaching the author name or abstract. -- Macro: .AU Specifies the author's name, which appears on the line (or lines) immediately following. You can specify multiple authors as follows: .AU John Doe .AI University of West Bumblefuzz .AU Martha Buck .AI Monolithic Corporation ... -- Macro: .AI Specifies the author's institution. You can specify multiple institutions in the same way that you specify multiple authors. -- Macro: .AB [no'] Begins the abstract. The default is to print the word ABSTRACT, centered and in italics, above the text of the abstract. The word no' as an optional argument suppresses this heading. -- Macro: .AE Ends the abstract. The following is example mark-up for a title page. .RP .TL The Inevitability of Code Bloat in Commercial and Free Software .AU J. Random Luser .AI University of West Bumblefuzz .AB This report examines the long-term growth of the code bases in two large, popular software packages; the free Emacs and the commercial Microsoft Word. While differences appear in the type or order of features added, due to the different methodologies used, the results are the same in the end. .PP The free software approach is shown to be superior in that while free software can become as bloated as commercial offerings, free software tends to have fewer serious bugs and the added features are in line with user demand. .AE ... the rest of the paper follows ... File: groff, Node: ms Body Text, Next: ms Page Layout, Prev: ms Cover Page Macros, Up: ms 4.3.5 Body text --------------- This section describes macros used to mark up the body of your document. Examples include paragraphs, sections, and other groups. * Menu: * Paragraphs in ms:: * Headings in ms:: * Highlighting in ms:: * Lists in ms:: * Indentation values in ms:: * Tabstops in ms:: * ms Displays and Keeps:: * ms Insertions:: * Example multi-page table:: * ms Footnotes:: File: groff, Node: Paragraphs in ms, Next: Headings in ms, Prev: ms Body Text, Up: ms Body Text 4.3.5.1 Paragraphs .................. The following paragraph types are available. -- Macro: .PP -- Macro: .LP Sets a paragraph with an initial indentation. -- Macro: .QP Sets a paragraph that is indented at both left and right margins. The effect is identical to the HTML <BLOCKQUOTE>' element. The next paragraph or heading returns margins to normal. -- Macro: .XP Sets a paragraph whose lines are indented, except for the first line. This is a Berkeley extension. The following markup uses all four paragraph macros. .NH 2 Cases used in the study .LP The following software and versions were considered for this report. .PP For commercial software, we chose .B "Microsoft Word for Windows" , starting with version 1.0 through the current version (Word 2000). .PP For free software, we chose .B Emacs , from its first appearance as a standalone editor through the current version (v20). See [Bloggs 2002] for details. .QP Franklin's Law applied to software: software expands to outgrow both RAM and disk space over time. .LP Bibliography: .XP Bloggs, Joseph R., .I "Everyone's a Critic" , Underground Press, March 2002. A definitive work that answers all questions and criticisms about the quality and usability of free software. The PORPHANS' register (*note ms Document Control Registers::) operates in conjunction with each of these macros, to inhibit the printing of orphan lines at the bottom of any page. File: groff, Node: Headings in ms, Next: Highlighting in ms, Prev: Paragraphs in ms, Up: ms Body Text 4.3.5.2 Headings ................ Use headings to create a hierarchical structure for your document. The ms' macros print headings in *bold*, using the same font family and point size as the body text. The following describes the heading macros: -- Macro: .NH curr-level -- Macro: .NH S level0 ... Numbered heading. The argument is either a numeric argument to indicate the level of the heading, or the letter S' followed by numeric arguments to set the heading level explicitly. If you specify heading levels out of sequence, such as invoking .NH 3' after .NH 1', groff' prints a warning on standard error. -- String: \*[SN] -- String: \*[SN-DOT] -- String: \*[SN-NO-DOT] After invocation of NH', the assigned section number is made available in the strings SN-DOT' (exactly as it appears in the printed section heading) and SN-NO-DOT' (with the final period omitted). The string SN' is also defined, as an alias for SN-DOT'; if preferred, you may redefine it as an alias for SN-NO-DOT', by including the initialization .ds SN-NO-DOT .als SN SN-NO-DOT *before* your first use of NH', or simply .als SN SN-NO-DOT *after* your first use of NH'. -- Macro: .SH [match-level] Unnumbered subheading. The optional MATCH-LEVEL argument is a GNU extension. It is a number indicating the level of the heading, in a manner analogous to the CURR-LEVEL argument to .NH'. Its purpose is to match the point size, at which the heading is printed, to the size of a numbered heading at the same level, when the GROWPS' and PSINCR' heading size adjustment mechanism is in effect. *Note ms Document Control Registers::. The HORPHANS' register (*note ms Document Control Registers::) operates in conjunction with the NH' and SH' macros, to inhibit the printing of orphaned section headings at the bottom of any page. File: groff, Node: Highlighting in ms, Next: Lists in ms, Prev: Headings in ms, Up: ms Body Text 4.3.5.3 Highlighting .................... The ms' macros provide a variety of methods to highlight or emphasize text: -- Macro: .B [txt [post [pre]]] Sets its first argument in *bold type*. If you specify a second argument, groff' prints it in the previous font after the bold text, with no intervening space (this allows you to set punctuation after the highlighted text without highlighting the punctuation). Similarly, it prints the third argument (if any) in the previous font *before* the first argument. For example, .B foo ) ( prints (*foo*). If you give this macro no arguments, groff' prints all text following in bold until the next highlighting, paragraph, or heading macro. -- Macro: .R [txt [post [pre]]] Sets its first argument in roman (or regular) type. It operates similarly to the B' macro otherwise. -- Macro: .I [txt [post [pre]]] Sets its first argument in _italic type_. It operates similarly to the B' macro otherwise. -- Macro: .CW [txt [post [pre]]] Sets its first argument in a constant width face'. It operates similarly to the B' macro otherwise. -- Macro: .BI [txt [post [pre]]] Sets its first argument in bold italic type. It operates similarly to the B' macro otherwise. -- Macro: .BX [txt] Prints its argument and draws a box around it. If you want to box a string that contains spaces, use a digit-width space (\0'). -- Macro: .UL [txt [post]] Prints its first argument with an underline. If you specify a second argument, groff' prints it in the previous font after the underlined text, with no intervening space. -- Macro: .LG Prints all text following in larger type (two points larger than the current point size) until the next font size, highlighting, paragraph, or heading macro. You can specify this macro multiple times to enlarge the point size as needed. -- Macro: .SM Prints all text following in smaller type (two points smaller than the current point size) until the next type size, highlighting, paragraph, or heading macro. You can specify this macro multiple times to reduce the point size as needed. -- Macro: .NL Prints all text following in the normal point size (that is, the value of the PS' register). -- String: \*[{] -- String: \*[}] Text enclosed with \*{' and \*}' is printed as a superscript. File: groff, Node: Lists in ms, Next: Indentation values in ms, Prev: Highlighting in ms, Up: ms Body Text 4.3.5.4 Lists ............. The IP' macro handles duties for all lists. -- Macro: .IP [marker [width]] The MARKER is usually a bullet glyph (\[bu]') for unordered lists, a number (or auto-incrementing number register) for numbered lists, or a word or phrase for indented (glossary-style) lists. The WIDTH specifies the indentation for the body of each list item; its default unit is n'. Once specified, the indentation remains the same for all list items in the document until specified again. The PORPHANS' register (*note ms Document Control Registers::) operates in conjunction with the IP' macro, to inhibit the printing of orphaned list markers at the bottom of any page. The following is an example of a bulleted list. A bulleted list: .IP \[bu] 2 lawyers .IP \[bu] guns .IP \[bu] money Produces: A bulleted list: o lawyers o guns o money The following is an example of a numbered list. .nr step 1 1 A numbered list: .IP \n[step] 3 lawyers .IP \n+[step] guns .IP \n+[step] money Produces: A numbered list: 1. lawyers 2. guns 3. money Note the use of the auto-incrementing number register in this example. The following is an example of a glossary-style list. A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! Produces: A glossary-style list: lawyers Two or more attorneys. guns Firearms, preferably large-caliber. money Gotta pay for those lawyers and guns! In the last example, the IP' macro places the definition on the same line as the term if it has enough space; otherwise, it breaks to the next line and starts the definition below the term. This may or may not be the effect you want, especially if some of the definitions break and some do not. The following examples show two possible ways to force a break. The first workaround uses the br' request to force a break after printing the term or label. A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns .br Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! The second workaround uses the \p' escape to force the break. Note the space following the escape; this is important. If you omit the space, groff' prints the first word on the same line as the term or label (if it fits) *then* breaks the line. A glossary-style list: .IP lawyers 0.4i Two or more attorneys. .IP guns \p Firearms, preferably large-caliber. .IP money Gotta pay for those lawyers and guns! To set nested lists, use the RS' and RE' macros. *Note Indentation values in ms::, for more information. For example: .IP \[bu] 2 Lawyers: .RS .IP \[bu] Dewey, .IP \[bu] Cheatham, .IP \[bu] and Howe. .RE .IP \[bu] Guns Produces: o Lawyers: o Dewey, o Cheatham, o and Howe. o Guns File: groff, Node: Indentation values in ms, Next: Tabstops in ms, Prev: Lists in ms, Up: ms Body Text 4.3.5.5 Indentation values .......................... In many situations, you may need to indentation a section of text while still wrapping and filling. *Note Lists in ms::, for an example of nested lists. -- Macro: .RS -- Macro: .RE These macros begin and end an indented section. The PI' register controls the amount of indentation, allowing the indented text to line up under hanging and indented paragraphs. *Note ms Displays and Keeps::, for macros to indentation and turn off filling. File: groff, Node: Tabstops in ms, Next: ms Displays and Keeps, Prev: Indentation values in ms, Up: ms Body Text 4.3.5.6 Tab Stops ................. Use the ta' request to define tab stops as needed. *Note Tabs and Fields::. -- Macro: .TA Use this macro to reset the tab stops to the default for ms' (every 5n). You can redefine the TA' macro to create a different set of default tab stops. File: groff, Node: ms Displays and Keeps, Next: ms Insertions, Prev: Tabstops in ms, Up: ms Body Text 4.3.5.7 Displays and keeps .......................... Use displays to show text-based examples or figures (such as code listings). Displays turn off filling, so lines of code are displayed as-is without inserting br' requests in between each line. Displays can be "kept" on a single page, or allowed to break across pages. -- Macro: .DS L -- Macro: .LD -- Macro: .DE Left-justified display. The .DS L' call generates a page break, if necessary, to keep the entire display on one page. The LD' macro allows the display to break across pages. The DE' macro ends the display. -- Macro: .DS I -- Macro: .ID -- Macro: .DE Indents the display as defined by the DI' register. The .DS I' call generates a page break, if necessary, to keep the entire display on one page. The ID' macro allows the display to break across pages. The DE' macro ends the display. -- Macro: .DS B -- Macro: .BD -- Macro: .DE Sets a block-centered display: the entire display is left-justified, but indented so that the longest line in the display is centered on the page. The .DS B' call generates a page break, if necessary, to keep the entire display on one page. The BD' macro allows the display to break across pages. The DE' macro ends the display. -- Macro: .DS C -- Macro: .CD -- Macro: .DE Sets a centered display: each line in the display is centered. The .DS C' call generates a page break, if necessary, to keep the entire display on one page. The CD' macro allows the display to break across pages. The DE' macro ends the display. -- Macro: .DS R -- Macro: .RD -- Macro: .DE Right-justifies each line in the display. The .DS R' call generates a page break, if necessary, to keep the entire display on one page. The RD' macro allows the display to break across pages. The DE' macro ends the display. -- Macro: .Ds -- Macro: .De These two macros were formerly provided as aliases for DS' and DE', respectively. They have been removed, and should no longer be used. The original implementations of DS' and DE' are retained, and should be used instead. X11 documents which actually use Ds' and De' always load a specific macro file from the X11 distribution (macros.t') which provides proper definitions for the two macros. On occasion, you may want to "keep" other text together on a page. For example, you may want to keep two paragraphs together, or a paragraph that refers to a table (or list, or other item) immediately following. The ms' macros provide the KS' and KE' macros for this purpose. -- Macro: .KS -- Macro: .KE The KS' macro begins a block of text to be kept on a single page, and the KE' macro ends the block. -- Macro: .KF -- Macro: .KE Specifies a "floating keep"; if the keep cannot fit on the current page, groff' holds the contents of the keep and allows text following the keep (in the source file) to fill in the remainder of the current page. When the page breaks, whether by an explicit bp' request or by reaching the end of the page, groff' prints the floating keep at the top of the new page. This is useful for printing large graphics or tables that do not need to appear exactly where specified. You can also use the ne' request to force a page break if there is not enough vertical space remaining on the page. Use the following macros to draw a box around a section of text (such as a display). -- Macro: .B1 -- Macro: .B2 Marks the beginning and ending of text that is to have a box drawn around it. The B1' macro begins the box; the B2' macro ends it. Text in the box is automatically placed in a diversion (keep). File: groff, Node: ms Insertions, Next: Example multi-page table, Prev: ms Displays and Keeps, Up: ms Body Text 4.3.5.8 Tables, figures, equations, and references .................................................. The ms' macros support the standard groff' preprocessors: tbl', pic', eqn', and refer'. You mark text meant for preprocessors by enclosing it in pairs of tags as follows. -- Macro: .TS [H'] -- Macro: .TE Denotes a table, to be processed by the tbl' preprocessor. The optional argument H' to TS' instructs groff' to create a running header with the information up to the TH' macro. groff' prints the header at the beginning of the table; if the table runs onto another page, groff' prints the header on the next page as well. -- Macro: .PS -- Macro: .PE Denotes a graphic, to be processed by the pic' preprocessor. You can create a pic' file by hand, using the AT&T pic' manual available on the Web as a reference, or by using a graphics program such as xfig'. -- Macro: .EQ [align] -- Macro: .EN Denotes an equation, to be processed by the eqn' preprocessor. The optional ALIGN argument can be C', L', or I' to center (the default), left-justify, or indent the equation. -- Macro: .[ -- Macro: .] Denotes a reference, to be processed by the refer' preprocessor. The GNU refer(1)' man page provides a comprehensive reference to the preprocessor and the format of the bibliographic database. * Menu: * Example multi-page table:: File: groff, Node: Example multi-page table, Next: ms Footnotes, Prev: ms Insertions, Up: ms Body Text 4.3.5.9 An example multi-page table ................................... The following is an example of how to set up a table that may print across two or more pages. .TS H allbox expand; cb | cb . Text ...of heading... _ .TH .T& l | l . ... the rest of the table follows... .CW .TE File: groff, Node: ms Footnotes, Prev: Example multi-page table, Up: ms Body Text 4.3.5.10 Footnotes .................. The ms' macro package has a flexible footnote system. You can specify either numbered footnotes or symbolic footnotes (that is, using a marker such as a dagger symbol). -- String: \*[*] Specifies the location of a numbered footnote marker in the text. -- Macro: .FS -- Macro: .FE Specifies the text of the footnote. The default action is to create a numbered footnote; you can create a symbolic footnote by specifying a "mark" glyph (such as \[dg]' for the dagger glyph) in the body text and as an argument to the FS' macro, followed by the text of the footnote and the FE' macro. You can control how groff' prints footnote numbers by changing the value of the FF' register. *Note ms Document Control Registers::. Footnotes can be safely used within keeps and displays, but you should avoid using numbered footnotes within floating keeps. You can set a second \**' marker between a \**' and its corresponding .FS' entry; as long as each FS' macro occurs _after_ the corresponding \**' and the occurrences of .FS' are in the same order as the corresponding occurrences of \**'. File: groff, Node: ms Page Layout, Next: Differences from AT&T ms, Prev: ms Body Text, Up: ms 4.3.6 Page layout ----------------- The default output from the ms' macros provides a minimalist page layout: it prints a single column, with the page number centered at the top of each page. It prints no footers. You can change the layout by setting the proper number registers and strings. * Menu: * ms Headers and Footers:: * ms Margins:: * ms Multiple Columns:: * ms TOC:: * ms Strings and Special Characters:: File: groff, Node: ms Headers and Footers, Next: ms Margins, Prev: ms Page Layout, Up: ms Page Layout 4.3.6.1 Headers and footers ........................... For documents that do not distinguish between odd and even pages, set the following strings: -- String: \*[LH] -- String: \*[CH] -- String: \*[RH] Sets the left, center, and right headers. -- String: \*[LF] -- String: \*[CF] -- String: \*[RF] Sets the left, center, and right footers. For documents that need different information printed in the even and odd pages, use the following macros: -- Macro: .OH 'left'center'right' -- Macro: .EH 'left'center'right' -- Macro: .OF 'left'center'right' -- Macro: .EF 'left'center'right' The OH' and EH' macros define headers for the odd and even pages; the OF' and EF' macros define footers for the odd and even pages. This is more flexible than defining the individual strings. You can replace the quote ('') marks with any character not appearing in the header or footer text. File: groff, Node: ms Margins, Next: ms Multiple Columns, Prev: ms Headers and Footers, Up: ms Page Layout 4.3.6.2 Margins ............... You control margins using a set of number registers. *Note ms Document Control Registers::, for details. File: groff, Node: ms Multiple Columns, Next: ms TOC, Prev: ms Margins, Up: ms Page Layout 4.3.6.3 Multiple columns ........................ The ms' macros can set text in as many columns as will reasonably fit on the page. The following macros are available; all of them force a page break if a multi-column mode is already set. However, if the current mode is single-column, starting a multi-column mode does _not_ force a page break. -- Macro: .1C Single-column mode. -- Macro: .2C Two-column mode. -- Macro: .MC [width [gutter]] Multi-column mode. If you specify no arguments, it is equivalent to the 2C' macro. Otherwise, WIDTH is the width of each column and GUTTER is the space between columns. The MINGW' number register controls the default gutter width. File: groff, Node: ms TOC, Next: ms Strings and Special Characters, Prev: ms Multiple Columns, Up: ms Page Layout 4.3.6.4 Creating a table of contents .................................... The facilities in the ms' macro package for creating a table of contents are semi-automated at best. Assuming that you want the table of contents to consist of the document's headings, you need to repeat those headings wrapped in XS' and XE' macros. -- Macro: .XS [page] -- Macro: .XA [page] -- Macro: .XE These macros define a table of contents or an individual entry in the table of contents, depending on their use. The macros are very simple; they cannot indent a heading based on its level. The easiest way to work around this is to add tabs to the table of contents string. The following is an example: .NH 1 Introduction .XS Introduction .XE .LP ... .CW .NH 2 Methodology .XS Methodology .XE .LP ... You can manually create a table of contents by beginning with the XS' macro for the first entry, specifying the page number for that entry as the argument to XS'. Add subsequent entries using the XA' macro, specifying the page number for that entry as the argument to XA'. The following is an example: .XS 1 Introduction .XA 2 A Brief History of the Universe .XA 729 Details of Galactic Formation ... .XE -- Macro: .TC [no'] Prints the table of contents on a new page, setting the page number to *i* (Roman lowercase numeral one). You should usually place this macro at the end of the file, since groff' is a single-pass formatter and can only print what has been collected up to the point that the TC' macro appears. The optional argument no' suppresses printing the title specified by the string register TOC'. -- Macro: .PX [no'] Prints the table of contents on a new page, using the current page numbering sequence. Use this macro to print a manually-generated table of contents at the beginning of your document. The optional argument no' suppresses printing the title specified by the string register TOC'. The Groff and Friends HOWTO' includes a sed' script that automatically inserts XS' and XE' macro entries after each heading in a document. Altering the NH' macro to automatically build the table of contents is perhaps initially more difficult, but would save a great deal of time in the long run if you use ms' regularly. File: groff, Node: ms Strings and Special Characters, Prev: ms TOC, Up: ms Page Layout 4.3.6.5 Strings and Special Characters ...................................... The ms' macros provide the following predefined strings. You can change the string definitions to help in creating documents in languages other than English. -- String: \*[REFERENCES] Contains the string printed at the beginning of the references (bibliography) page. The default is References'. -- String: \*[ABSTRACT] Contains the string printed at the beginning of the abstract. The default is ABSTRACT'. -- String: \*[TOC] Contains the string printed at the beginning of the table of contents. -- String: \*[MONTH1] -- String: \*[MONTH2] -- String: \*[MONTH3] -- String: \*[MONTH4] -- String: \*[MONTH5] -- String: \*[MONTH6] -- String: \*[MONTH7] -- String: \*[MONTH8] -- String: \*[MONTH9] -- String: \*[MONTH10] -- String: \*[MONTH11] -- String: \*[MONTH12] Prints the full name of the month in dates. The default is January', February', etc. The following special characters are available(1) (*note ms Strings and Special Characters-Footnote-1::): -- String: \*[-] Prints an em dash. -- String: \*[Q] -- String: \*[U] Prints typographer's quotes in troff, and plain quotes in nroff. \*Q' is the left quote and \*U' is the right quote. Improved accent marks are available in the ms' macros. -- Macro: .AM Specify this macro at the beginning of your document to enable extended accent marks and special characters. This is a Berkeley extension. To use the accent marks, place them *after* the character being accented. Note that groff's native support for accents is superior to the following definitions. The following accent marks are available after invoking the AM' macro: -- String: \*['] Acute accent. -- String: \*[] Grave accent. -- String: \*[^] Circumflex. -- String: \*[,] Cedilla. -- String: \*[~] Tilde. -- String: \*[:] Umlaut. -- String: \*[v] Hacek. -- String: \*[_] Macron (overbar). -- String: \*[.] Underdot. -- String: \*[o] Ring above. The following are standalone characters available after invoking the AM' macro: -- String: \*[?] Upside-down question mark. -- String: \*[!] Upside-down exclamation point. -- String: \*[8] German ß ligature. -- String: \*[3] Yogh. -- String: \*[Th] Uppercase thorn. -- String: \*[th] Lowercase thorn. -- String: \*[D-] Uppercase eth. -- String: \*[d-] Lowercase eth. -- String: \*[q] Hooked o. -- String: \*[ae] Lowercase æ ligature. -- String: \*[Ae] Uppercase Æ ligature. File: groff, Node: ms Strings and Special Characters-Footnotes, Up: ms Strings and Special Characters (1) For an explanation what special characters are see *Note Special Characters::. File: groff, Node: Differences from AT&T ms, Next: Naming Conventions, Prev: ms Page Layout, Up: ms 4.3.7 Differences from AT&T ms' -------------------------------- This section lists the (minor) differences between the groff -ms' macros and AT&T troff -ms' macros. * The internals of groff -ms' differ from the internals of AT&T troff -ms'. Documents that depend upon implementation details of AT&T troff -ms' may not format properly with groff -ms'. * The general error-handling policy of groff -ms' is to detect and report errors, rather than silently to ignore them. * groff -ms' does not work in compatibility mode (this is, with the -C' option). * There is no special support for typewriter-like devices. * groff -ms' does not provide cut marks. * Multiple line spacing is not supported. Use a larger vertical spacing instead. * Some UNIX ms' documentation says that the CW' and GW' number registers can be used to control the column width and gutter width, respectively. These number registers are not used in groff -ms'. * Macros that cause a reset (paragraphs, headings, etc.) may change the indentation. Macros that change the indentation do not increment or decrement the indentation, but rather set it absolutely. This can cause problems for documents that define additional macros of their own. The solution is to use not the in' request but instead the RS' and RE' macros. * To make groff -ms' use the default page offset (which also specifies the left margin), the PO' register must stay undefined until the first -ms' macro is evaluated. This implies that PO' should not be used early in the document, unless it is changed also: Remember that accessing an undefined register automatically defines it. -- Register: \n[GS] This number register is set to 1 by the groff -ms' macros, but it is not used by the AT&T' troff -ms' macros. Documents that need to determine whether they are being formatted with AT&T' troff -ms' or groff -ms' should use this number register. * Menu: * Missing ms Macros:: * Additional ms Macros:: File: groff, Node: Missing ms Macros, Next: Additional ms Macros, Prev: Differences from AT&T ms, Up: Differences from AT&T ms 4.3.7.1 troff' macros not appearing in groff' ............................................... Macros missing from groff -ms' are cover page macros specific to Bell Labs and Berkeley. The macros known to be missing are: .TM' Technical memorandum; a cover sheet style .IM' Internal memorandum; a cover sheet style .MR' Memo for record; a cover sheet style .MF' Memo for file; a cover sheet style .EG' Engineer's notes; a cover sheet style .TR' Computing Science Tech Report; a cover sheet style .OK' Other keywords .CS' Cover sheet information .MH' A cover sheet macro File: groff, Node: Additional ms Macros, Prev: Missing ms Macros, Up: Differences from AT&T ms 4.3.7.2 groff' macros not appearing in AT&T troff' .................................................... The groff -ms' macros have a few minor extensions compared to the AT&T troff -ms' macros. -- Macro: .AM Improved accent marks. *Note ms Strings and Special Characters::, for details. -- Macro: .DS I Indented display. The default behavior of AT&T troff -ms' was to indent; the groff' default prints displays flush left with the body text. -- Macro: .CW Print text in constant width' (Courier) font. -- Macro: .IX Indexing term (printed on standard error). You can write a script to capture and process an index generated in this manner. The following additional number registers appear in groff -ms': -- Register: \n[MINGW] Specifies a minimum space between columns (for multi-column output); this takes the place of the GW' register that was documented but apparently not implemented in AT&T troff'. Several new string registers are available as well. You can change these to handle (for example) the local language. *Note ms Strings and Special Characters::, for details. File: groff, Node: Naming Conventions, Prev: Differences from AT&T ms, Up: ms 4.3.8 Naming Conventions ------------------------ The following conventions are used for names of macros, strings and number registers. External names available to documents that use the groff -ms' macros contain only uppercase letters and digits. Internally the macros are divided into modules; naming conventions are as follows: * Names used only within one module are of the form MODULE*'NAME. * Names used outside the module in which they are defined are of the form MODULE@'NAME. * Names associated with a particular environment are of the form ENVIRONMENT:'NAME; these are used only within the par' module. * NAME does not have a module prefix. * Constructed names used to implement arrays are of the form ARRAY!'INDEX. Thus the groff ms macros reserve the following names: * Names containing the characters *', @', and :'. * Names containing only uppercase letters and digits. File: groff, Node: me, Next: mm, Prev: ms, Up: Macro Packages 4.4 me' ======== See the meintro.me' and meref.me' documents in groff's doc' directory. File: groff, Node: mm, Prev: me, Up: Macro Packages 4.5 mm' ======== See the groff_mm(7)' man page (type man groff_mm' at the command line). File: groff, Node: gtroff Reference, Next: Preprocessors, Prev: Macro Packages, Up: Top 5 gtroff' Reference ******************** This chapter covers *all* of the facilities of gtroff'. Users of macro packages may skip it if not interested in details. * Menu: * Text:: * Measurements:: * Expressions:: * Identifiers:: * Embedded Commands:: * Registers:: * Manipulating Filling and Adjusting:: * Manipulating Hyphenation:: * Manipulating Spacing:: * Tabs and Fields:: * Character Translations:: * Troff and Nroff Mode:: * Line Layout:: * Line Control:: * Page Layout:: * Page Control:: * Fonts and Symbols:: * Sizes:: * Strings:: * Conditionals and Loops:: * Writing Macros:: * Page Motions:: * Drawing Requests:: * Traps:: * Diversions:: * Environments:: * Suppressing output:: * Colors:: * I/O:: * Postprocessor Access:: * Miscellaneous:: * Gtroff Internals:: * Debugging:: * Implementation Differences:: File: groff, Node: Text, Next: Measurements, Prev: gtroff Reference, Up: gtroff Reference 5.1 Text ======== gtroff' input files contain text with control commands interspersed throughout. But, even without control codes, gtroff' still does several things with the input text: * filling and adjusting * adding additional space after sentences * hyphenating * inserting implicit line breaks * Menu: * Filling and Adjusting:: * Hyphenation:: * Sentences:: * Tab Stops:: * Implicit Line Breaks:: * Input Conventions:: * Input Encodings:: File: groff, Node: Filling and Adjusting, Next: Hyphenation, Prev: Text, Up: Text 5.1.1 Filling and Adjusting --------------------------- When gtroff' reads text, it collects words from the input and fits as many of them together on one output line as it can. This is known as "filling". Once gtroff' has a "filled" line, it tries to "adjust" it. This means it widens the spacing between words until the text reaches the right margin (in the default adjustment mode). Extra spaces between words are preserved, but spaces at the end of lines are ignored. Spaces at the front of a line cause a "break" (breaks are explained in *Note Implicit Line Breaks::). *Note Manipulating Filling and Adjusting::. File: groff, Node: Hyphenation, Next: Sentences, Prev: Filling and Adjusting, Up: Text 5.1.2 Hyphenation ----------------- Since the odds are not great for finding a set of words, for every output line, which fit nicely on a line without inserting excessive amounts of space between words, gtroff' hyphenates words so that it can justify lines without inserting too much space between words. It uses an internal hyphenation algorithm (a simplified version of the algorithm used within TeX) to indicate which words can be hyphenated and how to do so. When a word is hyphenated, the first part of the word is added to the current filled line being output (with an attached hyphen), and the other portion is added to the next line to be filled. *Note Manipulating Hyphenation::. File: groff, Node: Sentences, Next: Tab Stops, Prev: Hyphenation, Up: Text 5.1.3 Sentences --------------- Although it is often debated, some typesetting rules say there should be different amounts of space after various punctuation marks. For example, the Chicago typsetting manual' says that a period at the end of a sentence should have twice as much space following it as would a comma or a period as part of an abbreviation. gtroff' does this by flagging certain characters (normally !', ?', and .') as "end-of-sentence" characters. When gtroff' encounters one of these characters at the end of a line, it appends a normal space followed by a "sentence space" in the formatted output. (This justifies one of the conventions mentioned in *Note Input Conventions::.) In addition, the following characters and symbols are treated transparently while handling end-of-sentence characters: "', '', )', ]', *', \[dg]', and \[rq]'. See the cflags' request in *Note Using Symbols::, for more details. To prevent the insertion of extra space after an end-of-sentence character (at the end of a line), append \&'. File: groff, Node: Tab Stops, Next: Implicit Line Breaks, Prev: Sentences, Up: Text 5.1.4 Tab Stops --------------- gtroff' translates "tabulator characters", also called "tabs" (normally code point ASCII 0x09' or EBCDIC 0x05'), in the input into movements to the next tabulator stop. These tab stops are initially located every half inch across the page. Using this, simple tables can be made easily. However, it can often be deceptive as the appearance (and width) of the text on a terminal and the results from gtroff' can vary greatly. Also, a possible sticking point is that lines beginning with tab characters are still filled, again producing unexpected results. For example, the following input 1 2 3 4 5 produces 1 2 3 4 5 *Note Tabs and Fields::. File: groff, Node: Implicit Line Breaks, Next: Input Conventions, Prev: Tab Stops, Up: Text 5.1.5 Implicit Line Breaks -------------------------- An important concept in gtroff' is the "break". When a break occurs, gtroff' outputs the partially filled line (unjustified), and resumes collecting and filling text on the next output line. There are several ways to cause a break in gtroff'. A blank line not only causes a break, but it also outputs a one-line vertical space (effectively a blank line). Note that this behaviour can be modified with the blank line macro request blm'. *Note Blank Line Traps::. A line that begins with a space causes a break and the space is output at the beginning of the next line. Note that this space isn't adjusted, even in fill mode. The end of file also causes a break - otherwise the last line of the document may vanish! Certain requests also cause breaks, implicitly or explicitly. This is discussed in *Note Manipulating Filling and Adjusting::. File: groff, Node: Input Conventions, Next: Input Encodings, Prev: Implicit Line Breaks, Up: Text 5.1.6 Input Conventions ----------------------- Since gtroff' does filling automatically, it is traditional in groff' not to try and type things in as nicely formatted paragraphs. These are some conventions commonly used when typing gtroff' text: * Break lines after punctuation, particularly at the end of a sentence and in other logical places. Keep separate phrases on lines by themselves, as entire phrases are often added or deleted when editing. * Try to keep lines less than 40-60 characters, to allow space for inserting more text. * Do not try to do any formatting in a WYSIWYG manner (i.e., don't try using spaces to get proper indentation). File: groff, Node: Input Encodings, Prev: Input Conventions, Up: Text 5.1.7 Input Encodings --------------------- Currently, the following input encodings are available. cp1047 This input encoding works only on EBCDIC platforms (and vice versa, the other input encodings don't work with EBCDIC); the file cp1047.tmac' is by default loaded at start-up. latin-1 This is the default input encoding on non-EBCDIC platforms; the file latin1.tmac' is loaded at start-up. latin-2 To use this encoding, either say .mso latin2.tmac' at the very beginning of your document or use -mlatin2' as a command line argument for groff'. latin-9 (latin-0) This encoding is intended (at least in Europe) to replace latin-1 encoding. The main difference to latin-1 is that latin-9 contains the Euro character. To use this encoding, either say .mso latin9.tmac' at the very beginning of your document or use -mlatin9' as a command line argument for groff'. Note that it can happen that some input encoding characters are not available for a particular output device. For example, saying groff -Tlatin1 -mlatin9 ... will fail if you use the Euro character in the input. Usually, this limitation is present only for devices which have a limited set of output glyphs (e.g. -Tascii' and -Tlatin1'); for other devices it is usually sufficient to install proper fonts which contain the necessary glyphs. Due to the importance of the Euro glyph in Europe, the groff package now comes with a POSTSCRIPT font called freeeuro.pfa' which provides various glyph shapes for the Euro. With other words, latin-9 encoding is supported for the -Tps' device out of the box (latin-2 isn't). By its very nature, -Tutf8' supports all input encodings; -Tdvi' has support for both latin-2 and latin-9 if the command line -mec' is used also to load the file ec.tmac' (which flips to the EC fonts). File: groff, Node: Measurements, Next: Expressions, Prev: Text, Up: gtroff Reference 5.2 Measurements ================ gtroff' (like many other programs) requires numeric parameters to specify various measurements. Most numeric parameters(1) (*note Measurements-Footnote-1::) may have a "measurement unit" attached. These units are specified as a single character which immediately follows the number or expression. Each of these units are understood, by gtroff', to be a multiple of its "basic unit". So, whenever a different measurement unit is specified gtroff' converts this into its "basic units". This basic unit, represented by a u', is a device dependent measurement which is quite small, ranging from 1/75th to 1/72000th of an inch. The values may be given as fractional numbers; however, fractional basic units are always rounded to integers. Some of the measurement units are completely independent of any of the current settings (e.g. type size) of gtroff'. i' Inches. An antiquated measurement unit still in use in certain backwards countries with incredibly low-cost computer equipment. One inch is equal to 2.54cm. c' Centimeters. One centimeter is equal to 0.3937in. p' Points. This is a typesetter's measurement used for measure type size. It is 72 points to an inch. P' Pica. Another typesetting measurement. 6 Picas to an inch (and 12 points to a pica). s' z' *Note Fractional Type Sizes::, for a discussion of these units. f' Fractions. Value is 65536. *Note Colors::, for usage. The other measurements understood by gtroff' depend on settings currently in effect in gtroff'. These are very useful for specifying measurements which should look proper with any size of text. m' Ems. This unit is equal to the current font size in points. So called because it is _approximately_ the width of the letter m' in the current font. n' Ens. In groff', this is half of an em. v' Vertical space. This is equivalent to the current line spacing. *Note Sizes::, for more information about this. M' 100ths of an em. * Menu: * Default Units:: File: groff, Node: Measurements-Footnotes, Up: Measurements (1) those that specify vertical or horizontal motion or a type size File: groff, Node: Default Units, Prev: Measurements, Up: Measurements 5.2.1 Default Units ------------------- Many requests take a default unit. While this can be helpful at times, it can cause strange errors in some expressions. For example, the line length request expects em units. Here are several attempts to get a line length of 3.5 inches and their results: 3.5i => 3.5i 7/2 => 0i 7/2i => 0i (7 / 2)u => 0i 7i/2 => 0.1i 7i/2u => 3.5i Everything is converted to basic units first. In the above example it is assumed that 1i equals 240u, and 1m equals 10p (thus 1m equals 33u). The value 7i/2 is first handled as 7i/2m, then converted to 1680u/66u which is 25u, and this is approximately 0.1i. As can be seen, a scaling indicator after a closing parenthesis is simply ignored. Thus, the safest way to specify measurements is to always attach a scaling indicator. If you want to multiply or divide by a certain scalar value, use u' as the unit for that value. File: groff, Node: Expressions, Next: Identifiers, Prev: Measurements, Up: gtroff Reference 5.3 Expressions =============== gtroff' has most arithmetic operators common to other languages: * Arithmetic: +' (addition), -' (subtraction), /' (division), *' (multiplication), %' (modulo). gtroff' only provides integer arithmetic. The internal type used for computing results is int', which is usually a 32bit signed integer. * Comparison: <' (less than), >' (greater than), <=' (less than or equal), >=' (greater than or equal), =' (equal), ==' (the same as ='). * Logical: &' (logical and), :' (logical or). * Unary operators: -' (negating, i.e. changing the sign), +' (just for completeness; does nothing in expressions), !' (logical not; this works only within if' and while' requests). See below for the use of unary operators in motion requests. * Extrema: >?' (maximum), <?' (minimum). Example: .nr x 5 .nr y 3 .nr z (\n[x] >? \n[y]) The register z' now contains 5. * Scaling: (C;E)'. Evaluate E using C as the default scaling indicator. If C is missing, ignore scaling indicators in the evaluation of E. Parentheses may be used as in any other language. However, in gtroff' they are necessary to ensure order of evaluation. gtroff' has no operator precedence; expressions are evaluated left to right. This means that gtroff' evaluates 3+5*4' as if it were parenthesized like (3+5)*4', not as 3+(5*4)', as might be expected. For many requests which cause a motion on the page, the unary operators +' and -' work differently if leading an expression. They then indicate a motion relative to the current position (down or up, respectively). Similarly, a leading |' operator indicates an absolute position. For vertical movements, it specifies the distance from the top of the page; for horizontal movements, it gives the distance from the beginning of the _input_ line. +' and -' are also treated differently by the following requests and escapes: bp', in', ll', lt', nm', nr', pl', pn', po', ps', pvs', rt', ti', \H', \R', and \s'. Here, leading plus and minus signs indicate increments and decrements. *Note Setting Registers::, for some examples. -- Escape: \B'anything' Return 1 if ANYTHING is a valid numeric expression; or 0 if ANYTHING is empty or not a valid numeric expression. Due to the way arguments are parsed, spaces are not allowed in expressions, unless the entire expression is surrounded by parentheses. *Note Request and Macro Arguments::, and *Note Conditionals and Loops::. File: groff, Node: Identifiers, Next: Embedded Commands, Prev: Expressions, Up: gtroff Reference 5.4 Identifiers =============== Like any other language, gtroff' has rules for properly formed "identifiers". In gtroff', an identifier can be made up of almost any printable character, with the exception of the following characters: * Whitespace characters (spaces, tabs, and newlines). * Backspace (ASCII 0x08' or EBCDIC 0x16') and character code 0x01'. * The following input characters are invalid and are ignored if groff' runs on a machine based on ASCII, causing a warning message of type input' (see *Note Debugging::, for more details): 0x00', 0x0B', 0x0D'-0x1F', 0x80'-0x9F'. And here are the invalid input characters if groff' runs on an EBCDIC host: 0x00', 0x08', 0x09', 0x0B', 0x0D'-0x14', 0x17'-0x1F', 0x30'-0x3F'. Currently, some of these reserved codepoints are used internally, thus making it non-trivial to extend gtroff' to cover Unicode or other character sets and encodings which use characters of these ranges. Note that invalid characters are removed before parsing; an identifier foo', followed by an invalid character, followed by bar' is treated as foobar'. For example, any of the following is valid. br PP (l end-list @_ Note that identifiers longer than two characters with a closing bracket (]') in its name can't be accessed with escape sequences which expect an identifier as a parameter. For example, \[foo]]' accesses the glyph foo', followed by ]', whereas \C'foo]'' really asks for glyph foo]'. To avoid problems with the refer' preprocessor, macro names should not start with [' or ]'. Due to backwards compatibility, everything after .[' and .]' is handled as a special argument to refer'. For example, .[foo' makes refer' to start a reference, using foo' as a parameter. -- Escape: \A'ident' Test whether an identifier IDENT is valid in gtroff'. It expands to the character 1 or 0 according to whether its argument (usually delimited by quotes) is or is not acceptable as the name of a string, macro, diversion, number register, environment, or font. It returns 0 if no argument is given. This is useful for looking up user input in some sort of associative table. \A'end-list' => 1 *Note Escapes::, for details on parameter delimiting characters. Identifiers in gtroff' can be any length, but, in some contexts, gtroff' needs to be told where identifiers end and text begins (and in different ways depending on their length): * Single character. * Two characters. Must be prefixed with (' in some situations. * Arbitrary length (gtroff' only). Must be bracketed with [' and ]' in some situations. Any length identifier can be put in brackets. Unlike many other programming languages, undefined identifiers are silently ignored or expanded to nothing. When gtroff' finds an undefined identifier, it emits a warning, doing the following: * If the identifier is a string, macro, or diversion, gtroff' defines it as empty. * If the identifier is a number register, gtroff' defines it with a value of 0. *Note Warnings::., *Note Interpolating Registers::, and *Note Strings::. Note that macros, strings, and diversions share the same name space. .de xxx . nop foo .. . .di xxx bar .br .di . .xxx => bar As can be seen in the previous example, gtroff' reuses the identifier xxx', changing it from a macro to a diversion. No warning is emitted! The contents of the first macro definition is lost. *Note Interpolating Registers::, and *Note Strings::. File: groff, Node: Embedded Commands, Next: Registers, Prev: Identifiers, Up: gtroff Reference 5.5 Embedded Commands ===================== Most documents need more functionality beyond filling, adjusting and implicit line breaking. In order to gain further functionality, gtroff' allows commands to be embedded into the text, in two ways. The first is a "request" which takes up an entire line, and does some large-scale operation (e.g. break lines, start new pages). The other is an "escape" which can be usually embedded anywhere in the text; most requests can accept it even as an argument. Escapes generally do more minor operations like sub- and superscripts, print a symbol, etc. * Menu: * Requests:: * Macros:: * Escapes:: File: groff, Node: Requests, Next: Macros, Prev: Embedded Commands, Up: Embedded Commands 5.5.1 Requests -------------- A request line begins with a control character, which is either a single quote ('', the "no-break control character") or a period (.', the normal "control character"). These can be changed; see *Note Character Translations::, for details. After this there may be optional tabs or spaces followed by an identifier which is the name of the request. This may be followed by any number of space-separated arguments (_no_ tabs here). Since a control character followed by whitespace only is ignored, it is common practice to use this feature for structuring the source code of documents or macro packages. .de foo . tm This is foo. .. . . .de bar . tm This is bar. .. Another possibility is to use the blank line macro request blm' by assigning an empty macro to it. .de do-nothing .. .blm do-nothing \" activate blank line macro .de foo . tm This is foo. .. .de bar . tm This is bar. .. .blm \" deactivate blank line macro *Note Blank Line Traps::. To begin a line with a control character without it being interpreted, precede it with \&'. This represents a zero width space, which means it does not affect the output. In most cases the period is used as a control character. Several requests cause a break implicitly; using the single quote control character prevents this. * Menu: * Request and Macro Arguments:: File: groff, Node: Request and Macro Arguments, Prev: Requests, Up: Requests 5.5.1.1 Request and Macro Arguments ................................... Arguments to requests and macros are processed much like the shell: The line is split into arguments according to spaces.(1) (*note Request and Macro Arguments-Footnote-1::) An argument to a macro which is intended to contain spaces can either be enclosed in double quotes, or have the spaces "escaped" with backslashes. This is _not_ true for requests. Here are a few examples for a hypothetical macro uh': .uh The Mouse Problem .uh "The Mouse Problem" .uh The\ Mouse\ Problem The first line is the uh' macro being called with 3 arguments, The', Mouse', and Problem'. The latter two have the same effect of calling the uh' macro with one argument, The Mouse Problem'.(2) (*note Request and Macro Arguments-Footnote-2::) A double quote which isn't preceded by a space doesn't start a macro argument. If not closing a string, it is printed literally. For example, .xxx a" "b c" "de"fg" has the arguments a"', b c', de', and fg"'. Don't rely on this obscure behaviour! There are two possibilities to get a double quote reliably. * Enclose the whole argument with double quotes and use two consecutive double quotes to represent a single one. This traditional solution has the disadvantage that double quotes don't survive argument expansion again if called in compatibility mode (using the -C' option of groff'): .de xx . tm xx: \\1' \\2' \\3' . . yy "\\1" "\\2" "\\3" .. .de yy . tm yy: \\1' \\2' \\3' .. .xx A "test with ""quotes""" . => xx: A' test with "quotes"' .' => yy: A' test with ' quotes""' If not in compatibility mode, you get the expected result xx: A' test with "quotes"' .' yy: A' test with "quotes"' .' since gtroff' preserves the input level. * Use the double quote glyph \(dq'. This works with and without compatibility mode enabled since gtroff' doesn't convert \(dq' back to a double quote input character. Not that this method won't work with UNIX troff' in general since the glyph dq' isn't defined normally. Double quotes in the ds' request are handled differently. *Note Strings::, for more details. File: groff, Node: Request and Macro Arguments-Footnotes, Up: Request and Macro Arguments (1) Plan 9's troff' implementation also allows tabs for argument separation - gtroff' intentionally doesn't support this. (2) The last solution, i.e., using escaped spaces, is "classical" in the sense that it can be found in most troff' documents. Nevertheless, it is not optimal in all situations, since \ ' inserts a fixed-width, non-breaking space character which can't stretch. gtroff' provides a different command \~' to insert a stretchable, non-breaking space. File: groff, Node: Macros, Next: Escapes, Prev: Requests, Up: Embedded Commands 5.5.2 Macros ------------ gtroff' has a "macro" facility for defining a series of lines which can be invoked by name. They are called in the same manner as requests - arguments also may be passed basically in the same manner. *Note Writing Macros::, and *Note Request and Macro Arguments::. File: groff, Node: Escapes, Prev: Macros, Up: Embedded Commands 5.5.3 Escapes ------------- Escapes may occur anywhere in the input to gtroff'. They usually begin with a backslash and are followed by a single character which indicates the function to be performed. The escape character can be changed; see *Note Character Translations::. Escape sequences which require an identifier as a parameter accept three possible syntax forms. * The next single character is the identifier. * If this single character is an opening parenthesis, take the following two characters as the identifier. Note that there is no closing parenthesis after the identifier. * If this single character is an opening bracket, take all characters until a closing bracket as the identifier. Examples: \fB \n(XX \*[TeX] Other escapes may require several arguments and/or some special format. In such cases the argument is traditionally enclosed in single quotes (and quotes are always used in this manual for the definitions of escape sequences). The enclosed text is then processed according to what that escape expects. Example: \l'1.5i\(bu' Note that the quote character can be replaced with any other character which does not occur in the argument (even a newline or a space character) in the following escapes: \o', \b', and \X'. This makes e.g. A caf \o e\' in Paris => A café in Paris possible, but it is better not to use this feature to avoid confusion. The following escapes sequences (which are handled similarly to characters since they don't take a parameter) are also allowed as delimiters: \%', \ ', \|', \^', \{', \}', \'', \', \-', \_', \!', \?', \@', ', \/', \,', \&', \:', \~', \0', \a', \c',
\d', \e', \E', \p', \r', \t', and \u'.  Again, don't use these
if possible.

No newline characters as delimiters are allowed in the following
escapes: \A', \B', \Z', \C', and \w'.

Finally, the escapes \D', \h', \H', \l', \L', \N', \R', \s',
\S', \v', and \x' can't use the following characters as delimiters:

* The digits 0'-9'.

* The (single-character) operators +-/*%<>=&:().'.

* The space, tab, and newline characters.

* All escape sequences except \%', \:', \{', \}', \'', \',
\-', \_', \!', \@', \/', \c', \e', and \p'.

To have a backslash (actually, the current escape character) appear
in the output several escapes are defined: \\', \e' or \E'.  These
are very similar, and only differ with respect to being used in macros
or diversions.  *Note Character Translations::, for an exact
description of those escapes.

*Note Implementation Differences::, *Note Copy-in Mode::, and *Note

File: groff,  Node: Comments,  Prev: Escapes,  Up: Escapes

................

Probably one of the most(1) (*note Comments-Footnote-1::) common forms
of escapes is the comment.

-- Escape: \"
Start a comment.  Everything to the end of the input line is
ignored.

This may sound simple, but it can be tricky to keep the comments
from interfering with the appearance of the final output.

If the escape is to the right of some text or a request, that
portion of the line is ignored, but the space leading up to it is
noticed by gtroff'.  This only affects the ds' and as' request
and its variants.

One possibly irritating idiosyncracy is that tabs must not be used
to line up comments.  Tabs are not treated as whitespace between
the request and macro arguments.

A comment on a line by itself is treated as a blank line, because
after eliminating the comment, that is all that remains:

Test
\" comment
Test

produces

Test

Test

To avoid this, it is common to start the line with .\"' which
causes the line to be treated as an undefined request and thus
ignored completely.

Another commenting scheme seen sometimes is three consecutive
single quotes ('''') at the beginning of a line.  This works, but
gtroff' gives a warning about an undefined macro (namely '''),
which is harmless, but irritating.

-- Escape: \#
To avoid all this, gtroff' has a new comment mechanism using the
\#' escape.  This escape works the same as \"' except that the
newline is also ignored:

Test
\# comment
Test

produces

Test Test

as expected.

-- Request: .ig [end]
Ignore all input until gtroff' encounters the macro named .'END
on a line by itself (or ..' if END is not specified).  This is
useful for commenting out large blocks of text:

text text text...
.ig
This is part of a large block
of text that has been
temporarily(?) commented out.

We can restore it simply by removing
the .ig request and the ".." at the
end of the block.
..
More text text text...

produces

text text text...  More text text text...

Note that the commented-out block of text does not cause a break.

The input is read in copy-mode; auto-incremented registers _are_
affected (*note Auto-increment::).

(1) Unfortunately, this is a lie.  But hopefully future gtroff'
hackers will believe it :-)'

File: groff,  Node: Registers,  Next: Manipulating Filling and Adjusting,  Prev: Embedded Commands,  Up: gtroff Reference

5.6 Registers
=============

Numeric variables in gtroff' are called "registers".  There are a
number of built-in registers, supplying anything from the date to
details of formatting parameters.

*Note Identifiers::, for details on register identifiers.

* Setting Registers::
* Interpolating Registers::
* Auto-increment::
* Assigning Formats::
* Built-in Registers::

File: groff,  Node: Setting Registers,  Next: Interpolating Registers,  Prev: Registers,  Up: Registers

5.6.1 Setting Registers
-----------------------

Define or set registers using the nr' request or the \R' escape.

-- Request: .nr ident value
-- Escape: \R'ident value'
Set number register IDENT to VALUE.  If IDENT doesn't exist,
gtroff' creates it.

The argument to \R' usually has to be enclosed in quotes.  *Note
Escapes::, for details on parameter delimiting characters.

The \R' escape doesn't produce an input token in gtroff'; with
other words, it vanishes completely after gtroff' has processed
it.

For example, the following two lines are equivalent:

.nr a (((17 + (3 * 4))) % 4)
\R'a (((17 + (3 * 4))) % 4)'
=> 1

Both nr' and \R' have two additional special forms to increment or
decrement a register.

-- Request: .nr ident +value
-- Request: .nr ident -value
-- Escape: \R'ident +value'
-- Escape: \R'ident -value'
Increment (decrement) register IDENT by VALUE.

.nr a 1
.nr a +1
\na
=> 2

To assign the negated value of a register to another register,
some care must be taken to get the desired result:

.nr a 7
.nr b 3
.nr a -\nb
\na
=> 4
.nr a (-\nb)
\na
=> -3

The surrounding parentheses prevent the interpretation of the
minus sign as a decrementing operator.  An alternative is to start
the assignment with a 0':

.nr a 7
.nr b -3
.nr a \nb
\na
=> 4
.nr a 0\nb
\na
=> -3

-- Request: .rr ident
Remove number register IDENT.  If IDENT doesn't exist, the request
is ignored.

-- Request: .rnn ident1 ident2
Rename number register IDENT1 to IDENT2.  If either IDENT1 or
IDENT2 doesn't exist, the request is ignored.

-- Request: .aln ident1 ident2
Create an alias IDENT1 for a number register IDENT2.  The new name
and the old name are exactly equivalent.  If IDENT1 is undefined,
a warning of type reg' is generated, and the request is ignored.
*Note Debugging::, for information about warnings.

File: groff,  Node: Interpolating Registers,  Next: Auto-increment,  Prev: Setting Registers,  Up: Registers

5.6.2 Interpolating Registers
-----------------------------

Numeric registers can be accessed via the \n' escape.

-- Escape: \ni
-- Escape: \n(id
-- Escape: \n[ident]
Interpolate number register with name IDENT (one-character name I,
two-character name ID).  This means that the value of the register
is expanded in-place while gtroff' is parsing the input line.
Nested assignments (also called indirect assignments) are possible.

.nr a 5
.nr as \na+\na
\n(as
=> 10

.nr a1 5
.nr ab 6
.ds str b
.ds num 1
\n[a\n[num]]
=> 5
\n[a\*[str]]
=> 6

File: groff,  Node: Auto-increment,  Next: Assigning Formats,  Prev: Interpolating Registers,  Up: Registers

5.6.3 Auto-increment
--------------------

Number registers can also be auto-incremented and auto-decremented.
The increment or decrement value can be specified with a third argument
to the nr' request or \R' escape.

-- Request: .nr ident value incr
Set number register IDENT to VALUE; the increment for
auto-incrementing is set to INCR.  Note that the \R' escape
doesn't support this notation.

To activate auto-incrementing, the escape \n' has a special syntax
form.

-- Escape: \n+i
-- Escape: \n-i
-- Escape: \n(+id
-- Escape: \n(-id
-- Escape: \n+(id
-- Escape: \n-(id
-- Escape: \n[+ident]
-- Escape: \n[-ident]
-- Escape: \n+[ident]
-- Escape: \n-[ident]
Before interpolating, increment or decrement IDENT (one-character
name I, two-character name ID) by the auto-increment value as
specified with the nr' request (or the \R' escape).  If no
auto-increment value has been specified, these syntax forms are
identical to \n'.

For example,

.nr a 0 1
.nr xx 0 5
.nr foo 0 -2
\n+a, \n+a, \n+a, \n+a, \n+a
.br
\n-(xx, \n-(xx, \n-(xx, \n-(xx, \n-(xx
.br
\n+[foo], \n+[foo], \n+[foo], \n+[foo], \n+[foo]

produces

1, 2, 3, 4, 5
-5, -10, -15, -20, -25
-2, -4, -6, -8, -10

To change the increment value without changing the value of a
register (A in the example), the following can be used:

.nr a \na 10

File: groff,  Node: Assigning Formats,  Next: Built-in Registers,  Prev: Auto-increment,  Up: Registers

5.6.4 Assigning Formats
-----------------------

When a register is used in the text of an input file (as opposed to
part of an expression), it is textually replaced (or interpolated) with
a representation of that number.  This output format can be changed to
a variety of formats (numbers, Roman numerals, etc.).  This is done
using the af' request.

-- Request: .af ident format
Change the output format of a number register.  The first argument
IDENT is the name of the number register to be changed, and the
second argument FORMAT is the output format.  The following output
formats are available:

1'
Decimal arabic numbers.  This is the default format: 0, 1, 2,
3, ....

0...0'
Decimal numbers with as many digits as specified.  So, 00'
would result in printing numbers as 01, 02, 03, ....

In fact, any digit instead of zero will do; gtroff' only
counts how many digits are specified.  As a consequence,
af''s default format 1' could be specified as 0' also (and
exactly this is returned by the \g' escape, see below).

I'
Upper-case Roman numerals: 0, I, II, III, IV, ....

i'
Lower-case Roman numerals: 0, i, ii, iii, iv, ....

A'
Upper-case letters: 0, A, B, C, ..., Z, AA, AB, ....

a'
Lower-case letters: 0, a, b, c, ..., z, aa, ab, ....

Omitting the number register format causes a warning of type
missing'.  *Note Debugging::, for more details.  Specifying a
nonexistent format causes an error.

The following example produces 10, X, j, 010':

.nr a 10
.af a 1           \" the default format
\na,
.af a I
\na,
.af a a
\na,
.af a 001
\na

The largest number representable for the i' and I' formats is
39999 (or -39999); UNIX troff' uses z' and w' to represent
10000 and 5000 in Roman numerals, and so does gtroff'.
Currently, the correct glyphs of Roman numeral five thousand and
Roman numeral ten thousand (Unicode code points U+2182' and
U+2181', respectively) are not available.

If IDENT doesn't exist, it is created.

Changing the output format of a read-only register causes an
error.  It is necessary to first copy the register's value to a
writeable register, then apply the af' request to this other
register.

-- Escape: \gi
-- Escape: \g(id
-- Escape: \g[ident]
Return the current format of the specified register IDENT
(one-character name I, two-character name ID).  For example, \ga'
after the previous example would produce the string 000'.  If the
register hasn't been defined yet, nothing is returned.

File: groff,  Node: Built-in Registers,  Prev: Assigning Formats,  Up: Registers

5.6.5 Built-in Registers
------------------------

The following lists some built-in registers which are not described
elsewhere in this manual.  Any register which begins with a .' is
read-only.  A complete listing of all built-in registers can be found in
*Note Register Index::.

\n[.F]'
This string-valued register returns the current input file name.

\n[.H]'
Horizontal resolution in basic units.

\n[.U]'
If gtroff' is called with the -U' command line option, the
number register .U' is set to 1, and zero otherwise.  *Note Groff
Options::.

\n[.V]'
Vertical resolution in basic units.

\n[seconds]'
The number of seconds after the minute, normally in the range 0
to 59, but can be up to 61 to allow for leap seconds.  Initialized
at start-up of gtroff'.

\n[minutes]'
The number of minutes after the hour, in the range 0 to 59.
Initialized at start-up of gtroff'.

\n[hours]'
The number of hours past midnight, in the range 0 to 23.
Initialized at start-up of gtroff'.

\n[dw]'
Day of the week (1-7).

\n[dy]'
Day of the month (1-31).

\n[mo]'
Current month (1-12).

\n[year]'
The current year.

\n[yr]'
The current year minus 1900.  Unfortunately, the documentation of
UNIX Version 7's troff' had a year 2000 bug: It incorrectly
claimed that yr' contains the last two digits of the year.  That
claim has never been true of either AT&T troff' or GNU troff'.
Old troff' input that looks like this:

'\" The following line stopped working after 1999
This document was formatted in 19\n(yr.

can be corrected as follows:

This document was formatted in \n[year].

or, to be portable to older troff' versions, as follows:

.nr y4 1900+\n(yr
This document was formatted in \n(y4.

\n[.c]'
\n[c.]'
The current _input_ line number.  Register .c' is read-only,
whereas c.' (a gtroff' extension) is writable also, affecting
both .c' and c.'.

\n[ln]'
The current _output_ line number after a call to the nm' request
to activate line numbering.

\n[.x]'
The major version number.  For example, if the version number is
1.03 then .x' contains 1'.

\n[.y]'
The minor version number.  For example, if the version number is
1.03 then .y' contains 03'.

\n[.Y]'
The revision number of groff'.

\n[]'
The process ID of gtroff'.

\n[.g]'
Always 1.  Macros should use this to determine whether they are
running under GNU troff'.

\n[.A]'
If the command line option -a' is used to produce an ASCII
approximation of the output, this is set to 1, zero otherwise.
*Note Groff Options::.

\n[.P]'
This register is set to 1 (and to 0 otherwise) if the current page
is actually being printed, i.e., if the -o' option is being used
to only print selected pages.  *Note Groff Options::, for more
information.

\n[.T]'
If gtroff' is called with the -T' command line option, the
number register .T' is set to 1, and zero otherwise.  *Note Groff
Options::.

\*[.T]'
A single read-write string register which contains the current
output device (for example, latin1' or ps').  This is the only
string register defined by gtroff'.

File: groff,  Node: Manipulating Filling and Adjusting,  Next: Manipulating Hyphenation,  Prev: Registers,  Up: gtroff Reference

======================================

Various ways of causing "breaks" were given in *Note Implicit Line
Breaks::.  The br' request likewise causes a break.  Several other
requests also cause breaks, but implicitly.  These are bp', ce',
cf', fi', fl', in', nf', rj', sp', ti', and trf'.

-- Request: .br
Break the current line, i.e., the input collected so far is emitted

If the no-break control character is used, gtroff' suppresses the
break:

a
'br
b
=> a b

Initially, gtroff' fills and adjusts text to both margins.  Filling
can be disabled via the nf' request and re-enabled with the fi'
request.

-- Request: .fi
-- Register: \n[.u]
Activate fill mode (which is the default).  This request implicitly
enables adjusting; it also inserts a break in the text currently
being filled.  The read-only number register .u' is set to 1.

The fill mode status is associated with the current environment
(*note Environments::).

See *Note Line Control::, for interaction with the \c' escape.

-- Request: .nf
Activate no-fill mode.  Input lines are output as-is, retaining
line breaks and ignoring the current line length.  This command
implicitly disables adjusting; it also causes a break.  The number
register .u' is set to 0.

The fill mode status is associated with the current environment
(*note Environments::).

See *Note Line Control::, for interaction with the \c' escape.

-- Register: \n[.j]

Activation and deactivation of adjusting is done implicitly with
calls to the fi' or nf' requests.

MODE can have one of the following values:

l'
Adjust text to the left margin.  This produces what is

r'
Adjust text to the right margin, producing ragged-left text.

c'
Center filled text.  This is different to the ce' request
which only centers text without filling.

b'
n'
Justify to both margins.  This is the default used by
gtroff'.

Finally, MODE can be the numeric argument returned by the .j'
register.

With no argument, gtroff' adjusts lines in the same way it did
before adjusting was deactivated (with a call to na', for
example).

text
text
text
.na
text
text

register .j'; it can be stored and subsequently used to set

The adjustment mode status is associated with the current
environment (*note Environments::).

-- Request: .na
Disable adjusting.  This request won't change the current
adjustment mode: A subsequent call to ad' uses the previous

The adjustment mode status is associated with the current
environment (*note Environments::).

-- Request: .brp
-- Escape: \p
Adjust the current line and cause a break.

In most cases this produces very ugly results since gtroff'
doesn't have a sophisticated paragraph building algorithm (as TeX
have, for example); instead, gtroff' fills and adjusts a paragraph
line by line:

This is an uninteresting sentence.
This is an uninteresting sentence.\p
This is an uninteresting sentence.

is formatted as

This is  an uninteresting  sentence.   This  is an
uninteresting                            sentence.
This is an uninteresting sentence.

-- Request: .ss word_space_size [sentence_space_size]
-- Register: \n[.ss]
-- Register: \n[.sss]
Change the size of a space between words.  It takes its units as
one twelfth of the space width parameter for the current font.
Initially both the WORD_SPACE_SIZE and SENTENCE_SPACE_SIZE are 12.
In fill mode, the values specify the minimum distance.

If two arguments are given to the ss' request, the second
argument sets the sentence space size.  If the second argument is
not given, sentence space size is set to WORD_SPACE_SIZE.  The
sentence space size is used in two circumstances: If the end of a
sentence occurs at the end of a line in fill mode, then both an
inter-word space and a sentence space are added; if two spaces
follow the end of a sentence in the middle of a line, then the
second space is a sentence space.  If a second argument is never
given to the ss' request, the behaviour of UNIX troff' is the
same as that exhibited by GNU troff'.  In GNU troff', as in UNIX
troff', a sentence should always be followed by either a newline
or two spaces.

The read-only number registers .ss' and .sss' hold the values of
the parameters set by the first and second arguments of the ss'
request.

The word space and sentence space values are associated with the
current environment (*note Environments::).

Contrary to AT&T troff', this request is _not_ ignored if a TTY
output device is used; the given values are then rounded down to a
multiple of 12 (*note Implementation Differences::).

The request is ignored if there is no parameter.

Another useful application of the ss' request is to insert
line break.  For example, paragraph-style footnotes could be
separated this way:

.ll 4.5i
1.\ This is the first footnote.\c
.ss 48
.nop
.ss 12
2.\ This is the second footnote.

The result:

1. This is the first footnote.        2. This
is the second footnote.

Note that the \h' escape produces unbreakable space.

-- Request: .ce [nnn]
-- Register: \n[.ce]
Center text.  While the .ad c' request also centers text, it
fills the text as well.  ce' does not fill the text it affects.
This request causes a break.  The number of lines still to be
centered is associated with the current environment (*note
Environments::).

The following example demonstrates the differences.  Here the
input:

.ll 4i
.ce 1000
This is a small text fragment which shows the differences
between the .ce' and the .ad c' request.
.ce 0

This is a small text fragment which shows the differences
between the .ce' and the .ad c' request.

And here the result:

This is a small text fragment which
shows the differences
between the .ce' and the .ad c' request.

This is a small text fragment which
shows the differences between the .ce'
and the .ad c' request.

With no arguments, ce' centers the next line of text.  NNN
specifies the number of lines to be centered.  If the argument is
zero or negative, centering is disabled.

The basic length for centering text is the line length (as set
with the ll' request) minus the indentation (as set with the in'
request).  Temporary indentation is ignored.

As can be seen in the previous example, it is a common idiom to
turn on centering for a large number of lines, and to turn off
centering after text to be centered.  This is useful for any
request which takes a number of lines as an argument.

The .ce' read-only number register contains the number of lines
remaining to be centered, as set by the ce' request.

-- Request: .rj [nnn]
-- Register: \n[.rj]
Justify unfilled text to the right margin.  Arguments are
identical to the ce' request.  The .rj' read-only number
register is the number of lines to be right-justified as set by
the rj' request.  This request causes a break.  The number of
lines still to be right-justified is associated with the current
environment (*note Environments::).

File: groff,  Node: Manipulating Hyphenation,  Next: Manipulating Spacing,  Prev: Manipulating Filling and Adjusting,  Up: gtroff Reference

5.8 Manipulating Hyphenation
============================

Here a description of requests which influence hyphenation.

-- Request: .hy [mode]
-- Register: \n[.hy]
Enable hyphenation.  The request has an optional numeric argument,
MODE, to restrict hyphenation if necessary:

1'
The default argument if MODE is omitted.  Hyphenate without
restrictions.  This is also the start-up value of gtroff'.

2'
Do not hyphenate the last word on a page or column.

4'
Do not hyphenate the last two characters of a word.

8'
Do not hyphenate the first two characters of a word.

Values in the previous table are additive.  For example, the
value 12 causes gtroff' to neither hyphenate the last two nor the
first two characters of a word.

The current hyphenation restrictions can be found in the read-only
number register .hy'.

The hyphenation mode is associated with the current environment
(*note Environments::).

-- Request: .nh
Disable hyphenation (i.e., set the hyphenation mode to zero).  Note
that the hyphenation mode of the last call to hy' is not
remembered.

The hyphenation mode is associated with the current environment
(*note Environments::).

-- Request: .hlm [nnn]
-- Register: \n[.hlm]
-- Register: \n[.hlc]
Set the maximum number of consecutive hyphenated lines to NNN.  If
this number is negative, there is no maximum.  The default value
is -1 if NNN is omitted.  This value is associated with the
current environment (*note Environments::).  Only lines output
from a given environment count towards the maximum associated with
that environment.  Hyphens resulting from \%' are counted;
explicit hyphens are not.

The current setting of hlm' is available in the .hlm' read-only
number register.  Also the number of immediately preceding
consecutive hyphenated lines are available in the read-only number
register .hlc'.

-- Request: .hw word1 word2 ...
Define how WORD1, WORD2, etc. are to be hyphenated.  The words
must be given with hyphens at the hyphenation points.  For example:

.hw in-sa-lub-rious

Besides the space character, any character whose hyphenation code
value is zero can be used to separate the arguments of hw' (see
the documentation for the hcode' request below for more
information).  In addition, this request can be used more than
once.

Hyphenation exceptions specified with the hw' request are
associated with the current hyphenation language; it causes an
error if there is no current hyphenation language.

This request is ignored if there is no parameter.

In old versions of troff' there was a limited amount of space to
store such information; fortunately, with gtroff', this is no
longer a restriction.

-- Escape: \%
-- Escape: \:
To tell gtroff' how to hyphenate words on the fly, use the \%'
escape, also known as the "hyphenation character".  Preceding a
word with this character prevents it from being hyphenated;
putting it inside a word indicates to gtroff' that the word may
be hyphenated at that point.  Note that this mechanism only
affects that one occurrence of the word; to change the hyphenation
of a word for the entire document, use the hw' request.

The \:' escape inserts a zero-width break point (that is, the
word breaks but without adding a hyphen).

... check the /var/log/\:httpd/\:access_log file ...

Note that \X' and \Y' start a word, that is, the \%' escape in
(say) \X'...'\%foobar' and \Y'...'\%foobar' no longer prevents
hyphenation but inserts a hyphenation point at the beginning of
foobar'; most likely this isn't what you want to do.

-- Request: .hc [char]
Change the hyphenation character to CHAR.  This character then
works the same as the \%' escape, and thus, no longer appears in
the output.  Without an argument, hc' resets the hyphenation
character to be \%' (the default) only.

The hyphenation character is associated with the current
environment (*note Environments::).

-- Request: .hpf pattern_file
-- Request: .hpfa pattern_file
-- Request: .hpfcode a b [c d ...]
Read in a file of hyphenation patterns.  This file is searched for
in the same way as NAME.tmac' (or tmac.NAME') is searched for if
the -mNAME' option is specified.

It should have the same format as (simple) TeX patterns files.
More specifically, the following scanning rules are implemented.

* A percent sign starts a comment (up to the end of the line)
even if preceded by a backslash.

* No support for digraphs' like \$'. * ^^XX' (X is 0-9 or a-f) and ^^X' (character code of X in the range 0-127) are recognized; other use of ^' causes an error. * No macro expansion. * hpf' checks for the expression \patterns{...}' (possibly with whitespace before and after the braces). Everything between the braces is taken as hyphenation patterns. Consequently, {' and }' are not allowed in patterns. * Similarly, \hyphenation{...}' gives a list of hyphenation exceptions. * \endinput' is recognized also. * For backwards compatibility, if \patterns' is missing, the whole file is treated as a list of hyphenation patterns (only recognizing the %' character as the start of a comment). If no hpf' request is specified (either in the document or in a macro package), gtroff' won't hyphenate at all. The hpfa' request appends a file of patterns to the current list. The hpfcode' request defines mapping values for character codes in hyphenation patterns. hpf' or hpfa' then apply the mapping (after reading the patterns) before replacing or appending them to the current list of patterns. Its arguments are pairs of character codes - integers from 0 to 255. The request maps character code A to code B, code C to code D, and so on. You can use character codes which would be invalid otherwise. The set of hyphenation patterns is associated with the current language set by the hla' request. The hpf' request is usually invoked by the troffrc' or troffrc-end' file; by default, troffrc' loads hyphenation patterns and exceptions for American English (in files hyphen.us' and hyphenex.us'). A second call to hpf' (for the same language) will replace the hyphenation patterns with the new ones. Invoking hpf' causes an error if there is no current hyphenation language. -- Request: .hcode c1 code1 [c2 code2 ...] Set the hyphenation code of character C1 to CODE1, that of C2 to CODE2, etc. A hyphenation code must be a single input character (not a special character) other than a digit or a space. To make hyphenation work, hyphenation codes must be set up. At start-up, groff only assigns hyphenation codes to the letters a'-z' (mapped to themselves) and to the letters A'-Z' (mapped to a'-z'); all other hyphenation codes are set to zero. Normally, hyphenation patterns contain only lowercase letters which should be applied regardless of case. With other words, the words FOO' and Foo' should be hyphenated exactly the same way as the word foo' is hyphenated, and this is what hcode' is good for. Words which contain other letters won't be hyphenated properly if the corresponding hyphenation patterns actually do contain them. For example, the following hcode' requests are necessary to assign hyphenation codes to the letters ÄäÖöÜüß' (this is needed for German): .hcode ä ä Ä ä .hcode ö ö Ö ö .hcode ü ü Ü ü .hcode ß ß Without those assignments, groff treats German words like Kindergärten' (the plural form of kindergarten') as two substrings kinderg' and rten' because the hyphenation code of the umlaut a is zero by default. There is a German hyphenation pattern which covers kinder', so groff finds the hyphenation kin-der'. The other two hyphenation points (kin-der-gär-ten') are missed. This request is ignored if it has no parameter. -- Request: .hym [length] -- Register: \n[.hym] Set the (right) hyphenation margin to LENGTH. If the current adjustment mode is not b' or n', the line is not hyphenated if it is shorter than LENGTH. Without an argument, the hyphenation margin is reset to its default value, which is 0. The default scaling indicator for this request is m'. The hyphenation margin is associated with the current environment (*note Environments::). A negative argument resets the hyphenation margin to zero, emitting a warning of type range'. The current hyphenation margin is available in the .hym' read-only number register. -- Request: .hys [hyphenation_space] -- Register: \n[.hys] Set the hyphenation space to HYPHENATION_SPACE. If the current adjustment mode is b' or n', don't hyphenate the line if it can be justified by adding no more than HYPHENATION_SPACE extra space to each word space. Without argument, the hyphenation space is set to its default value, which is 0. The default scaling indicator for this request is m'. The hyphenation space is associated with the current environment (*note Environments::). A negative argument resets the hyphenation space to zero, emitting a warning of type range'. The current hyphenation space is available in the .hys' read-only number register. -- Request: .shc [glyph] Set the "soft hyphen character" to GLYPH.(1) (*note Manipulating Hyphenation-Footnote-1::) If the argument is omitted, the soft hyphen character is set to the default glyph $$hy' (this is the start-up value of gtroff' also). The soft hyphen character is the glyph that is inserted when a word is hyphenated at a line break. If the soft hyphen character does not exist in the font of the character immediately preceding a potential break point, then the line is not broken at that point. Neither definitions (specified with the char' request) nor translations (specified with the tr' request) are considered when finding the soft hyphen character. -- Request: .hla language -- Register: \n[.hla] Set the current hyphenation language to the string LANGUAGE. Hyphenation exceptions specified with the hw' request and hyphenation patterns specified with the hpf' and hpfa' requests are both associated with the current hyphenation language. The hla' request is usually invoked by the troffrc' or the troffrc-end' files; troffrc' sets the default language to us'. The current hyphenation language is available as a string in the read-only number register .hla'. .ds curr_language \n[.hla] \*[curr_language] => us File: groff, Node: Manipulating Hyphenation-Footnotes, Up: Manipulating Hyphenation (1) "Soft hyphen character" is a misnomer since it is an output glyph. File: groff, Node: Manipulating Spacing, Next: Tabs and Fields, Prev: Manipulating Hyphenation, Up: gtroff Reference 5.9 Manipulating Spacing ======================== -- Request: .sp [distance] Space downwards DISTANCE. With no argument it advances 1 line. A negative argument causes gtroff' to move up the page the specified distance. If the argument is preceded by a |' then gtroff' moves that distance from the top of the page. This request causes a line break. The default scaling indicator is v'. If a vertical trap is sprung during execution of sp', the amount of vertical space after the trap is discarded. For example, this .de xxx .. . .wh 0 xxx . .pl 5v foo .sp 2 bar .sp 50 baz results in foo bar baz The amount of discarded space is available in the number register .trunc'. To protect sp' against vertical traps, use the vpt' request: .vpt 0 .sp -3 .vpt 1 -- Request: .ls [nnn] -- Register: \n[.L] Output NNN-1 blank lines after each line of text. With no argument, gtroff' uses the previous value before the last ls' call. .ls 2 \" This causes double-spaced output .ls 3 \" This causes triple-spaced output .ls \" Again double-spaced The line spacing is associated with the current environment (*note Environments::). The read-only number register .L' contains the current line spacing setting. *Note Changing Type Sizes::, for the requests vs' and pvs' as alternatives to ls'. -- Escape: \x'spacing' -- Register: \n[.a] Sometimes, extra vertical spacing is only needed occasionally, e.g. to allow space for a tall construct (like an equation). The \x' escape does this. The escape is given a numerical argument, usually enclosed in quotes (like \x'3p''); the default scaling indicator is v'. If this number is positive extra vertical space is inserted below the current line. A negative number adds space above. If this escape is used multiple times on the same line, the maximum of the values is used. *Note Escapes::, for details on parameter delimiting characters. The .a' read-only number register contains the most recent (nonnegative) extra vertical line space. Using \x' can be necessary in combination with the \b' escape, as the following example shows. This is a test with the \[rs]b escape. .br This is a test with the \[rs]b escape. .br This is a test with \b'xyz'\x'-1m'\x'1m'. .br This is a test with the \[rs]b escape. .br This is a test with the \[rs]b escape. produces This is a test with the \b escape. This is a test with the \b escape. x This is a test with y. z This is a test with the \b escape. This is a test with the \b escape. -- Request: .ns -- Request: .rs -- Register: \n[.ns] Enable "no-space mode". In this mode, spacing (either via sp' or via blank lines) is disabled. The bp' request to advance to the next page is also disabled, except if it is accompanied by a page number (see *Note Page Control::, for more information). This mode ends when actual text is output or the rs' request is encountered which ends no-space mode. The read-only number register .ns' is set to 1 as long as no-space mode is active. This request is useful for macros that conditionally insert vertical space before the text starts (for example, a paragraph macro could insert some space except when it is the first paragraph after a section header). File: groff, Node: Tabs and Fields, Next: Character Translations, Prev: Manipulating Spacing, Up: gtroff Reference 5.10 Tabs and Fields ==================== A tab character (ASCII char 9, EBCDIC char 5) causes a horizontal movement to the next tab stop (much like it did on a typewriter). -- Escape: \t This escape is a non-interpreted tab character. In copy mode (*note Copy-in Mode::), \t' is the same as a real tab character. -- Request: .ta [n1 n2 ... nn T r1 r2 ... rn] -- Register: \n[.tabs] Change tab stop positions. This request takes a series of tab specifiers as arguments (optionally divided into two groups with the letter T') which indicate where each tab stop is to be (overriding any previous settings). Tab stops can be specified absolutely, i.e., as the distance from the left margin. For example, the following sets 6 tab stops every one inch. .ta 1i 2i 3i 4i 5i 6i Tab stops can also be specified using a leading +' which means that the specified tab stop is set relative to the previous tab stop. For example, the following is equivalent to the previous example. .ta 1i +1i +1i +1i +1i +1i gtroff' supports an extended syntax to specify repeat values after the T' mark (these values are always taken as relative) - this is the usual way to specify tabs set at equal intervals. The following is, yet again, the same as the previous examples. It does even more since it defines an infinite number of tab stops separated by one inch. .ta T 1i Now we are ready to interpret the full syntax given at the beginning: Set tabs at positions N1, N2, ..., NN and then set tabs at NN+R1, NN+R2, ..., NN+RN and then at NN+RN+R1, NN+RN+R2, ..., NN+RN+RN, and so on. Example: 4c +6c T 3c 5c 2c' is equivalent to 4c 10c 13c 18c 20c 23c 28c 30c ...'. The material in each tab column (i.e., the column between two tab stops) may be justified to the right or left or centered in the column. This is specified by appending R', L', or C' to the tab specifier. The default justification is L'. Example: .ta 1i 2iC 3iR Some notes: * The default unit of the ta' request is m'. * A tab stop is converted into a non-breakable horizontal movement which can be neither stretched nor squeezed. For example, .ds foo a\tb\tc .ta T 5i \*[foo] creates a single line which is a bit longer than 10 inches (a string is used to show exactly where the tab characters are). Now consider the following: .ds bar a\tb b\tc .ta T 5i \*[bar] gtroff' first converts the tab stops of the line into unbreakable horizontal movements, then splits the line after the second b' (assuming a sufficiently short line length). Usually, this isn't what the user wants. * Superfluous tabs (i.e., tab characters which do not correspond to a tab stop) are ignored except the first one which delimits the characters belonging to the last tab stop for right-justifying or centering. Consider the following example .ds Z foo\tbar\tfoo .ds ZZ foo\tbar\tfoobar .ds ZZZ foo\tbar\tfoo\tbar .ta 2i 4iR \*[Z] .br \*[ZZ] .br \*[ZZZ] .br which produces the following output: foo bar foo foo bar foobar foo bar foobar The first line right-justifies the second foo' relative to the tab stop. The second line right-justifies foobar'. The third line finally right-justifies only foo' because of the additional tab character which marks the end of the string belonging to the last defined tab stop. * Tab stops are associated with the current environment (*note Environments::). * Calling ta' without an argument removes all tab stops. * The start-up value of gtroff' is T 0.8i'. The read-only number register .tabs' contains a string representation of the current tab settings suitable for use as an argument to the ta' request. .ds tab-string \n[.tabs] \*[tab-string] => T120u The troff' version of the Plan 9 operating system uses register .S' for the same purpose. -- Request: .tc [fill-glyph] Normally gtroff' fills the space to the next tab stop with whitespace. This can be changed with the tc' request. With no argument gtroff' reverts to using whitespace, which is the default. The value of this "tab repetition character" is associated with the current environment (*note Environments::).(1) (*note Tabs and Fields-Footnote-1::) -- Request: .linetabs n -- Register: \n[.linetabs] If N is missing or not zero, enable "line-tabs" mode, or disable it otherwise (the default). In line-tabs mode, gtroff' computes tab distances relative to the (current) output line instead of the input line. For example, the following code: .ds x a\t\c .ds y b\t\c .ds z c .ta 1i 3i \*x \*y \*z in normal mode, results in the output a b c in line-tabs mode, the same code outputs a b c Line-tabs mode is associated with the current environment. The read-only register .linetabs' is set to 1 if in line-tabs mode, and 0 in normal mode. * Menu: * Leaders:: * Fields:: File: groff, Node: Tabs and Fields-Footnotes, Up: Tabs and Fields (1) "Tab repetition character" is a misnomer since it is an output glyph. File: groff, Node: Leaders, Next: Fields, Prev: Tabs and Fields, Up: Tabs and Fields 5.10.1 Leaders -------------- Sometimes it may may be desirable to use the tc' request to fill a particular tab stop with a given glyph (for example dots in a table of contents), but also normal tab stops on the rest of the line. For this gtroff' provides an alternate tab mechanism, called "leaders" which does just that. A leader character (character code 1) behaves similarly to a tab character: It moves to the next tab stop. The only difference is that for this movement, the fill glyph defaults to a period character and not to space. -- Escape: \a This escape is a non-interpreted leader character. In copy mode (*note Copy-in Mode::), \a' is the same as a real leader character. -- Request: .lc [fill-glyph] Declare the "leader repetition character".(1) (*note Leaders-Footnote-1::) Without an argument, leaders act the same as tabs (i.e., using whitespace for filling). gtroff''s start-up value is a dot (.'). The value of the leader repetition character is associated with the current environment (*note Environments::). For a table of contents, to name an example, tab stops may be defined so that the section number is one tab stop, the title is the second with the remaining space being filled with a line of dots, and then the page number slightly separated from the dots. .ds entry 1.1\tFoo\a\t12 .lc . .ta 1i 5i +.25i \*[entry] This produces 1.1 Foo.......................................... 12 File: groff, Node: Leaders-Footnotes, Up: Leaders (1) "Leader repetition character" is a misnomer since it is an output glyph. File: groff, Node: Fields, Prev: Leaders, Up: Tabs and Fields 5.10.2 Fields ------------- "Fields" are a more general way of laying out tabular data. A field is defined as the data between a pair of "delimiting characters". It contains substrings which are separated by "padding characters". The width of a field is the distance on the _input_ line from the position where the field starts to the next tab stop. A padding character inserts stretchable space similar to TeX's \hss' command (thus it can even be negative) to make the sum of all substring lengths plus the stretchable space equal to the field width. If more than one padding character is inserted, the available space is evenly distributed among them. -- Request: .fc [delim-char [padding-char]] Define a delimiting and a padding character for fields. If the latter is missing, the padding character defaults to a space character. If there is no argument at all, the field mechanism is disabled (which is the default). Note that contrary to e.g. the tab repetition character, delimiting and padding characters are _not_ associated to the current environment (*note Environments::). Example: .fc # ^ .ta T 3i #foo^bar^smurf# .br #foo^^bar^smurf# and here the result: foo bar smurf foo bar smurf File: groff, Node: Character Translations, Next: Troff and Nroff Mode, Prev: Tabs and Fields, Up: gtroff Reference 5.11 Character Translations =========================== The control character (.') and the no-break control character ('') can be changed with the cc' and c2' requests, respectively. -- Request: .cc [c] Set the control character to C. With no argument the default control character .' is restored. The value of the control character is associated with the current environment (*note Environments::). -- Request: .c2 [c] Set the no-break control character to C. With no argument the default control character '' is restored. The value of the no-break control character is associated with the current environment (*note Environments::). -- Request: .eo Disable the escape mechanism completely. After executing this request, the backslash character \' no longer starts an escape sequence. This request can be very helpful in writing macros since it is not necessary then to double the escape character. Here an example: .\" This is a simplified version of the .\" .BR request from the man macro package .eo .de BR . ds result \& . while (\n[.] >= 2) \{\ . as result \fB\1\fR\2 . shift 2 . \} . if \n[.] .as result \fB\1 \*[result] . ft R .. .ec -- Request: .ec [c] Set the escape character to C. With no argument the default escape character \' is restored. It can be also used to re-enable the escape mechanism after an eo' request. Note that changing the escape character globally will likely break macro packages since gtroff' has no mechanism to intern' macros, i.e., to convert a macro definition into an internal form which is independent of its representation (TeX has this mechanism). If a macro is called, it is executed literally. -- Request: .ecs -- Request: .ecr The ecs' request saves the current escape character in an internal register. Use this request in combination with the ec' request to temporarily change the escape character. The ecr' request restores the escape character saved with ecs'. Without a previous call to ecs', this request sets the escape character to \'. -- Escape: \\ -- Escape: \e -- Escape: \E Print the current escape character (which is the backslash character \' by default). \\' is a delayed' backslash; more precisely, it is the default escape character followed by a backslash, which no longer has special meaning due to the leading escape character. It is _not_ an escape sequence in the usual sense! In any unknown escape sequence \X' the escape character is ignored and X is printed. But if X is equal to the current escape character, no warning is emitted. As a consequence, only at top-level or in a diversion a backslash glyph is printed; in copy-in mode, it expands to a single backslash which then combines with the following character to an escape sequence. The \E' escape differs from \e' by printing an escape character that is not interpreted in copy mode. Use this to define strings with escapes that work when used in copy mode (for example, as a macro argument). The following example defines strings to begin and end a superscript: .ds { \v'-.3m'\s'\En[.s]*60/100' .ds } \s0\v'.3m' Another example to demonstrate the differences between the various escape sequences, using a strange escape character, -'. .ec - .de xxx --A'123' .. .xxx => -A'foo' The result is surprising for most users, expecting 1' since foo' is a valid identifier. What has happened? As mentioned above, the leading escape character makes the following character ordinary. Written with the default escape character the sequence --' becomes \-' - this is the minus sign. If the escape character followed by itself is a valid escape sequence, only \E' yields the expected result: .ec - .de xxx -EA'123' .. .xxx => 1 -- Escape: \. Similar to \\', the sequence \.' isn't a real escape sequence. As before, a warning message is suppressed if the escape character is followed by a dot, and the dot itself is printed. .de foo . nop foo . . de bar . nop bar \\.. . .. .foo .bar => foo bar The first backslash is consumed while the macro is read, and the second is swallowed while exexuting macro foo'. A "translation" is a mapping of an input character to an output glyph. The mapping occurs at output time, i.e., the input character gets assigned the metric information of the mapped output character right before input tokens are converted to nodes (*note Gtroff Internals::, for more on this process). -- Request: .tr abcd... -- Request: .trin abcd... Translate character A to glyph B, character C to glyph D, etc. If there is an odd number of arguments, the last one is translated to an unstretchable space (\ '). The trin' request is identical to tr', but when you unformat a diversion with asciify' it ignores the translation. *Note Diversions::, for details about the asciify' request. Some notes: * Special characters (\(XX', \[XXX]', \C'XXX'', \'', \', \-', \_'), glyphs defined with the char' request, and numbered glyphs (\N'XXX'') can be translated also. * The \e' escape can be translated also. * Characters can be mapped onto the \%' and \~' escapes (but \%' and \~' can't be mapped onto another glyph). * The following characters can't be translated: space (with one exception, see below), backspace, newline, leader (and \a'), tab (and \t'). * Translations are not considered for finding the soft hyphen character set with the shc' request. * The pair C\&' (this is an arbitrary character C followed by the zero width space character) maps this character to nothing. .tr a\& foo bar => foo br It is even possible to map the space character to nothing: .tr aa \& foo bar => foobar As shown in the example, the space character can't be the first character/glyph pair as an argument of tr'. Additionally, it is not possible to map the space character to any other glyph; requests like .tr aa x' undo .tr aa \&' instead. If justification is active, lines are justified in spite of the empty' space character (but there is no minimal distance, i.e. the space character, between words). * After an output glyph has been constructed (this happens at the moment immediately before the glyph is appended to an output glyph list, either by direct output, in a macro, diversion, or string), it is no longer affected by tr'. * Translating character to glyphs where one of them or both are undefined is possible also; tr' does not check whether the entities in its argument do exist. *Note Gtroff Internals::. * troff' no longer has a hard-coded dependency on Latin-1; all charXXX' entities have been removed from the font description files. This has a notable consequence which shows up in warnings like can't find character with input code XXX' if the tr' request isn't handled properly. Consider the following translation: .tr éÉ This maps input character é' onto glyph É', which is identical to glyph char201'. But this glyph intentionally doesn't exist! Instead, \[char201]' is treated as an input character entity and is by default mapped onto \['E]', and gtroff' doesn't handle translations of translations. The right way to write the above translation is .tr é\['E] With other words, the first argument of tr' should be an input character or entity, and the second one a glyph entity. * Without an argument, the tr' request is ignored. -- Request: .trnt abcd... trnt' is the same as the tr' request except that the translations do not apply to text that is transparently throughput into a diversion with \!'. *Note Diversions::, for more information. For example, .tr ab .di x \!.tm a .di .x prints b' to the standard error stream; if trnt' is used instead of tr' it prints a'. File: groff, Node: Troff and Nroff Mode, Next: Line Layout, Prev: Character Translations, Up: gtroff Reference 5.12 Troff and Nroff Mode ========================= Originally, nroff' and troff' were two separate programs, the former for TTY output, the latter for everything else. With GNU troff', both programs are merged into one executable, sending its output to a device driver (grotty' for TTY devices, grops' for POSTSCRIPT, etc.) which interprets the intermediate output of gtroff'. For UNIX troff' it makes sense to talk about "Nroff mode" and "Troff mode" since the differences are hardcoded. For GNU troff', this distinction is not appropriate because gtroff' simply takes the information given in the font files for a particular device without handling requests specially if a TTY output device is used. Usually, a macro package can be used with all output devices. Nevertheless, it is sometimes necessary to make a distinction between TTY and non-TTY devices: gtroff' provides two built-in conditions n' and t' for the if', ie', and while' requests to decide whether gtroff' shall behave like nroff' or like troff'. -- Request: .troff Make the t' built-in condition true (and the n' built-in condition false) for if', ie', and while' conditional requests. This is the default if gtroff' (_not_ groff') is started with the -R' switch to avoid loading of the start-up files troffrc' and troffrc-end'. Without -R', gtroff' stays in troff mode if the output device is not a TTY (e.g. ps'). -- Request: .nroff Make the n' built-in condition true (and the t' built-in condition false) for if', ie', and while' conditional requests. This is the default if gtroff' uses a TTY output device; the code for switching to nroff mode is in the file tty.tmac' which is loaded by the start-up file troffrc'. *Note Conditionals and Loops::, for more details on built-in conditions. File: groff, Node: Line Layout, Next: Line Control, Prev: Troff and Nroff Mode, Up: gtroff Reference 5.13 Line Layout ================ The following drawing shows the dimensions which gtroff' uses for placing a line of output onto the page. They are labeled with the request which manipulates each dimension. -->| in |<-- |<-----------ll------------>| +----+----+----------------------+----+ | : : : | +----+----+----------------------+----+ -->| po |<-- |<--------paper width---------------->| These dimensions are: po' "Page offset" - this is the leftmost position of text on the final output, defining the "left margin". in' "Indentation" - this is the distance from the left margin where text is printed. ll' "Line length" - this is the distance from the left margin to right margin. A simple demonstration: .ll 3i This is text without indentation. The line length has been set to 3\~inch. .in +.5i .ll -.5i Now the left and right margins are both increased. .in .ll Calling .in and .ll without parameters restore the previous values. Result: This is text without indenta- tion. The line length has been set to 3 inch. Now the left and right margins are both increased. Calling .in and .ll without parameters restore the previ- ous values. -- Request: .po [offset] -- Request: .po +offset -- Request: .po -offset -- Register: \n[.o] Set horizontal page offset to OFFSET (or increment or decrement the current value by OFFSET). Note that this request does not cause a break, so changing the page offset in the middle of text being filled may not yield the expected result. The initial value is 1i. For TTY output devices, it is set to 0 in the startup file troffrc'; the default scaling indicator is m' (and not v' as incorrectly documented in the original UNIX troff manual). The current page offset can be found in the read-only number register .o'. If po' is called without an argument, the page offset is reset to the previous value before the last call to po'. .po 3i \n[.o] => 720 .po -1i \n[.o] => 480 .po \n[.o] => 720 -- Request: .in [indent] -- Request: .in +indent -- Request: .in -indent -- Register: \n[.i] Set indentation to INDENT (or increment or decrement the current value by INDENT). This request causes a break. Initially, there is no indentation. If in' is called without an argument, the indentation is reset to the previous value before the last call to in'. The default scaling indicator is m'. The indentation is associated with the current environment (*note Environments::). If a negative indentation value is specified (which is not allowed), gtroff' emits a warning of type range' and sets the indentation to zero. The effect of in' is delayed until a partially collected line (if it exists) is output. A temporary indentation value is reset to zero also. The current indentation (as set by in') can be found in the read-only number register .i'. -- Request: .ti offset -- Request: .ti +offset -- Request: .ti -offset -- Register: \n[.in] Temporarily indent the next output line by OFFSET. If an increment or decrement value is specified, adjust the temporary indentation relative to the value set by the in' request. This request causes a break; its value is associated with the current environment (*note Environments::). The default scaling indicator is m'. A call of ti' without an argument is ignored. If the total indentation value is negative (which is not allowed), gtroff' emits a warning of type range' and sets the temporary indentation to zero. Total indentation' is either OFFSET if specified as an absolute value, or the temporary plus normal indentation, if OFFSET is given as a relative value. The effect of ti' is delayed until a partially collected line (if it exists) is output. The read-only number register .in' is the indentation that applies to the current output line. The difference between .i' and .in' is that the latter takes into account whether a partially collected line still uses the old indentation value or a temporary indentation value is active. -- Request: .ll [length] -- Request: .ll +length -- Request: .ll -length -- Register: \n[.l] -- Register: \n[.ll] Set the line length to LENGTH (or increment or decrement the current value by LENGTH). Initially, the line length is set to 6.5i. The effect of ll' is delayed until a partially collected line (if it exists) is output. The default scaling indicator is m'. If ll' is called without an argument, the line length is reset to the previous value before the last call to ll'. If a negative line length is specified (which is not allowed), gtroff' emits a warning of type range' and sets the line length to zero. The line length is associated with the current environment (*note Environments::). The current line length (as set by ll') can be found in the read-only number register .l'. The read-only number register .ll' is the line length that applies to the current output line. Similar to .i' and .in', the difference between .l' and .ll' is that the latter takes into account whether a partially collected line still uses the old line length value. File: groff, Node: Line Control, Next: Page Layout, Prev: Line Layout, Up: gtroff Reference 5.14 Line Control ================= It is important to understand how gtroff' handles input and output lines. Many escapes use positioning relative to the input line. For example, this This is a \h'|1.2i'test. This is a \h'|1.2i'test. produces This is a test. This is a test. The main usage of this feature is to define macros which act exactly at the place where called. .\" A simple macro to underline a word .de underline . nop \\1\l'|0\[ul]' .. In the above example, |0' specifies a negative distance from the current position (at the end of the just emitted argument \1') back to the beginning of the input line. Thus, the \l' escape draws a line from right to left. gtroff' makes a difference between input and output line continuation; the latter is also called "interrupting" a line. -- Escape: \<RET> -- Escape: \c -- Register: \n[.int] Continue a line. \<RET>' (this is a backslash at the end of a line immediately followed by a newline) works on the input level, suppressing the effects of the following newline in the input. This is a \ .test => This is a .test The |' operator is also affected. \c' works on the output level. Anything after this escape on the same line is ignored, except \R' which works as usual. Anything before \c' on the same line will be appended to the current partial output line. The next non-command line after an interrupted line counts as a new input line. The visual results depend on whether no-fill mode is active. * If no-fill mode is active (using the nf' request), the next input text line after \c' will be handled as a continuation of the same input text line. .nf This is a \c test. => This is a test. * If fill mode is active (using the fi' request), a word interrupted with \c' will be continued with the text on the next input text line, without an intervening space. This is a te\c st. => This is a test. Note that an intervening control line which causes a break is stronger than \c', flushing out the current partial line in the usual way. The .int' register contains a positive value if the last output line was interrupted with \c'; this is associated with the current environment (*note Environments::). File: groff, Node: Page Layout, Next: Page Control, Prev: Line Control, Up: gtroff Reference 5.15 Page Layout ================ gtroff' provides some very primitive operations for controlling page layout. -- Request: .pl [length] -- Request: .pl +length -- Request: .pl -length -- Register: \n[.p] Set the "page length" to LENGTH (or increment or decrement the current value by LENGTH). This is the length of the physical output page. The default scaling indicator is v'. The current setting can be found in the read-only number register .p'. Note that this only specifies the size of the page, not the top and bottom margins. Those are not set by gtroff' directly. *Note Traps::, for further information on how to do this. Negative pl' values are possible also, but not very useful: No trap is sprung, and each line is output on a single page (thus suppressing all vertical spacing). If no argument or an invalid argument is given, pl' sets the page length to 11i. gtroff' provides several operations which help in setting up top and bottom titles (or headers and footers). -- Request: .tl 'left'center'right' Print a "title line". It consists of three parts: a left justified portion, a centered portion, and a right justified portion. The argument separator '' can be replaced with any character not occurring in the title line. The %' character is replaced with the current page number. This character can be changed with the pc' request (see below). Without argument, tl' is ignored. Some notes: * A title line is not restricted to the top or bottom of a page. * tl' prints the title line immediately, ignoring a partially filled line (which stays untouched). * It is not an error to omit closing delimiters. For example, .tl /foo' is equivalent to .tl /foo///': It prints a title line with the left justified word foo'; the centered and right justfied parts are empty. * tl' accepts the same parameter delimiting characters as the \A' escape; see *Note Escapes::. -- Request: .lt [length] -- Request: .lt +length -- Request: .lt -length -- Register: \n[.lt] The title line is printed using its own line length, which is specified (or incremented or decremented) with the lt' request. Initially, the title line length is set to 6.5i. If a negative line length is specified (which is not allowed), gtroff' emits a warning of type range' and sets the title line length to zero. The default scaling indicator is m'. If lt' is called without an argument, the title length is reset to the previous value before the last call to lt'. The current setting of this is available in the .lt' read-only number register; it is associated with the current environment (*note Environments::). -- Request: .pn page -- Request: .pn +page -- Request: .pn -page -- Register: \n[.pn] Change (increase or decrease) the page number of the _next_ page. The only argument is the page number; the request is ignored without a parameter. The read-only number register .pn' contains the number of the next page: either the value set by a pn' request, or the number of the current page plus 1. -- Request: .pc [char] Change the page number character (used by the tl' request) to a different character. With no argument, this mechanism is disabled. Note that this doesn't affect the number register %'. *Note Traps::. File: groff, Node: Page Control, Next: Fonts and Symbols, Prev: Page Layout, Up: gtroff Reference 5.16 Page Control ================= -- Request: .bp [page] -- Request: .bp +page -- Request: .bp -page -- Register: \n[%] Stop processing the current page and move to the next page. This request causes a break. It can also take an argument to set (increase, decrease) the page number of the next page (which actually becomes the current page after bp' has finished). The difference between bp' and pn' is that pn' does not cause a break or actually eject a page. *Note Page Layout::. .de newpage \" define macro 'bp \" begin page 'sp .5i \" vertical space .tl 'left top'center top'right top' \" title 'sp .3i \" vertical space .. \" end macro bp' has no effect if not called within the top-level diversion (*note Diversions::). The read-write register %' holds the current page number. The number register .pe' is set to 1 while bp' is active. *Note Page Location Traps::. -- Request: .ne [space] It is often necessary to force a certain amount of space before a new page occurs. This is most useful to make sure that there is not a single "orphan" line left at the bottom of a page. The ne' request ensures that there is a certain distance, specified by the first argument, before the next page is triggered (see *Note Traps::, for further information). The default scaling indicator for ne' is v'; the default value of SPACE is 1v if no argument is given. For example, to make sure that no fewer than 2 lines get orphaned, do the following before each paragraph: .ne 2 text text text ne' will then automatically cause a page break if there is space for one line only. -- Request: .sv [space] -- Request: .os sv' is similar to the ne' request; it reserves the specified amount of vertical space. If the desired amount of space exists before the next trap (or the bottom page boundary if no trap is set), the space is output immediately (ignoring a partially filled line which stays untouched). If there is not enough space, it is stored for later output via the os' request. The default value is 1v if no argument is given; the default scaling indicator is v'. Both sv' and os' ignore no-space mode. While the sv' request allows negative values for SPACE, os' will ignore them. -- Register: \n[nl] This register contains the current vertical position. If the vertical position is zero and the top of page transition hasn't happened yet, nl' is set to negative value. gtroff' itself does this at the very beginning of a document before anything has been printed, but the main usage is to plant a header trap on a page if this page has already started. Consider the following: .de xxx . sp . tl ''Header'' . sp .. . First page. .bp .wh 0 xxx .nr nl (-1) Second page. Result: First page. ... Header Second page. ... Without resetting nl' to a negative value, the just planted trap would be active beginning with the _next_ page, not the current one. *Note Diversions::, for a comparison with the .h' and .d' registers. File: groff, Node: Fonts and Symbols, Next: Sizes, Prev: Page Control, Up: gtroff Reference 5.17 Fonts and Symbols ====================== gtroff' can switch fonts at any point in the text. The basic set of fonts is R', I', B', and BI'. These are Times Roman, Italic, Bold, and Bold Italic. For non-TTY devices, there is also at least one symbol font which contains various special symbols (Greek, mathematics). * Menu: * Changing Fonts:: * Font Families:: * Font Positions:: * Using Symbols:: * Special Fonts:: * Artificial Fonts:: * Ligatures and Kerning:: File: groff, Node: Changing Fonts, Next: Font Families, Prev: Fonts and Symbols, Up: Fonts and Symbols 5.17.1 Changing Fonts --------------------- -- Request: .ft [font] -- Escape: \ff -- Escape: \f(fn -- Escape: \f[font] -- Register: \n[.sty] The ft' request and the \f' escape change the current font to FONT (one-character name F, two-character name FN). If FONT is a style name (as set with the sty' request or with the styles' command in the DESC' file), use it within the current font family (as set with the fam' request, \F' escape, or with the family' command in the DESC' file). With no argument or using P' as an argument, .ft' switches to the previous font. Use \f[]' to do this with the escape. The old syntax forms \fP' or \f[P]' are also supported. Fonts are generally specified as upper-case strings, which are usually 1 to 4 characters representing an abbreviation or acronym of the font name. This is no limitation, just a convention. The example below produces two identical lines. eggs, bacon, .ft B spam .ft and sausage. eggs, bacon, \fBspam\fP and sausage. Note that \f' doesn't produce an input token in gtroff'. As a consequence, it can be used in requests like mc' (which expects a single character as an argument) to change the font on the fly: .mc \f[I]x\f[] The current style name is available in the read-only number register .sty' (this is a string-valued register); if the current font isn't a style, the empty string is returned. It is associated with the current environment. *Note Font Positions::, for an alternative syntax. -- Request: .ftr f [g] Translate font F to font G. Whenever a font named F is referred to in a \f' escape sequence, in the F' and S' conditional operators, or in the ft', ul', bd', cs', tkf', special', fspecial', fp', or sty' requests, font G is used. If G is missing or equal to F the translation is undone. File: groff, Node: Font Families, Next: Font Positions, Prev: Changing Fonts, Up: Fonts and Symbols 5.17.2 Font Families -------------------- Due to the variety of fonts available, gtroff' has added the concept of "font families" and "font styles". The fonts are specified as the concatenation of the font family and style. Specifying a font without the family part causes gtroff' to use that style of the current family. Currently, fonts for the devices -Tps', -Tdvi', -Tlj4', -Tlbp', and the X11 fonts are set up to this mechanism. By default, gtroff' uses the Times family with the four styles R', I', B', and BI'. This way, it is possible to use the basic four fonts and to select a different font family on the command line (*note Groff Options::). -- Request: .fam [family] -- Register: \n[.fam] -- Escape: \Ff -- Escape: \F(fm -- Escape: \F[family] -- Register: \n[.fn] Switch font family to FAMILY (one-character name F, two-character name FM). If no argument is given, switch back to the previous font family. Use \F[]' to do this with the escape. Note that \FP' doesn't work; it selects font family P' instead. The value at start-up is T'. The current font family is available in the read-only number register .fam' (this is a string-valued register); it is associated with the current environment. spam, .fam H \" helvetica family spam, \" used font is family H + style R = HR .ft B \" family H + style B = font HB spam, .fam T \" times family spam, \" used font is family T + style B = TB .ft AR \" font AR (not a style) baked beans, .ft R \" family T + style R = font TR and spam. Note that \F' doesn't produce an input token in gtroff'. As a consequence, it can be used in requests like mc' (which expects a single character as an argument) to change the font family on the fly: .mc \F[P]x\F[] The .fn' register contains the current "real font name" of the current font. This is a string-valued register. If the current font is a style, the value of \n[.fn]' is the proper concatenation of family and style name. -- Request: .sty n style Associate STYLE with font position N. A font position can be associated either with a font or with a style. The current font is the index of a font position and so is also either a font or a style. If it is a style, the font that is actually used is the font which name is the concatenation of the name of the current family and the name of the current style. For example, if the current font is 1 and font position 1 is associated with style R' and the current font family is T', then font TR' will be used. If the current font is not a style, then the current family is ignored. If the requests cs', bd', tkf', uf', or fspecial' are applied to a style, they will instead be applied to the member of the current family corresponding to that style. N must be a non-negative integer value. The default family can be set with the -f' option (*note Groff Options::). The styles' command in the DESC' file controls which font positions (if any) are initially associated with styles rather than fonts. For example, the default setting for POSTSCRIPT fonts styles R I B BI is equivalent to .sty 1 R .sty 2 I .sty 3 B .sty 4 BI fam' and \F' always check whether the current font position is valid; this can give surprising results if the current font position is associated with a style. In the following example, we want to access the POSTSCRIPT font FooBar' from the font family Foo': .sty \n[.fp] Bar .fam Foo => warning: can't find font FooR' The default font position at start-up is 1; for the POSTSCRIPT device, this is associated with style R', so gtroff' tries to open FooR'. A solution to this problem is to use a dummy font like the following: .fp 0 dummy TR \" set up dummy font at position 0 .sty \n[.fp] Bar \" register style Bar' .ft 0 \" switch to font at position 0 .fam Foo \" activate family Foo' .ft Bar \" switch to font FooBar' *Note Font Positions::. File: groff, Node: Font Positions, Next: Using Symbols, Prev: Font Families, Up: Fonts and Symbols 5.17.3 Font Positions --------------------- For the sake of old phototypesetters and compatibility with old versions of troff', gtroff' has the concept of font "positions", on which various fonts are mounted. -- Request: .fp pos font [external-name] -- Register: \n[.f] -- Register: \n[.fp] Mount font FONT at position POS (which must be a non-negative integer). This numeric position can then be referred to with font changing commands. When gtroff' starts it is using font position 1 (which must exist; position 0 is unused usually at start-up). The current font in use, as a font position, is available in the read-only number register .f'. This can be useful to remember the current font for later recall. It is associated with the current environment (*note Environments::). .nr save-font \n[.f] .ft B ... text text text ... .ft \n[save-font] The number of the next free font position is available in the read-only number register .fp'. This is useful when mounting a new font, like so: .fp \n[.fp] NEATOFONT Fonts not listed in the DESC' file are automatically mounted on the next available font position when they are referenced. If a font is to be mounted explicitly with the fp' request on an unused font position, it should be mounted on the first unused font position, which can be found in the .fp' register. Although gtroff' does not enforce this strictly, it is not allowed to mount a font at a position whose number is much greater (approx. 1000 positions) than that of any currently used position. The fp' request has an optional third argument. This argument gives the external name of the font, which is used for finding the font description file. The second argument gives the internal name of the font which is used to refer to the font in gtroff' after it has been mounted. If there is no third argument then the internal name is used as the external name. This feature makes it possible to use fonts with long names in compatibility mode. Both the ft' request and the \f' escape have alternative syntax forms to access font positions. -- Request: .ft nnn -- Escape: \fn -- Escape: \f(nn -- Escape: \f[nnn] Change the current font position to NNN (one-digit position N, two-digit position NN), which must be a non-negative integer. If NNN is associated with a style (as set with the sty' request or with the styles' command in the DESC' file), use it within the current font family (as set with the fam' request, the \F' escape, or with the family' command in the DESC' file). this is font 1 .ft 2 this is font 2 .ft \" switch back to font 1 .ft 3 this is font 3 .ft this is font 1 again *Note Changing Fonts::, for the standard syntax form. File: groff, Node: Using Symbols, Next: Special Fonts, Prev: Font Positions, Up: Fonts and Symbols 5.17.4 Using Symbols -------------------- A "glyph" is a graphical representation of a "character". While a character is an abstract entity containing semantic information, a glyph is something which can be actually seen on screen or paper. It is possible that a character has multiple glyph representation forms (for example, the character A' can be either written in a roman or an italic font, yielding two different glyphs); sometimes more than one character maps to a single glyph (this is a "ligature" - the most common is fi'). A "symbol" is simply a named glyph. Within gtroff', all glyph names of a particular font are defined in its font file. If the user requests a glyph not available in this font, gtroff' looks up an ordered list of "special fonts". By default, the POSTSCRIPT output device supports the two special fonts SS' (slanted symbols) and S' (symbols) (the former is looked up before the latter). Other output devices use different names for special fonts. Fonts mounted with the fonts' keyword in the DESC' file are globally available. To install additional special fonts locally (i.e. for a particular font), use the fspecial' request. Here the exact rules how gtroff' searches a given symbol: * If the symbol has been defined with the char' request, use it. This hides a symbol with the same name in the current font. * Check the current font. * If the symbol has been defined with the fchar' request, use it. * Check whether the current font has a font-specific list of special fonts; test all fonts in the order of appearance in the last fspecial' call if appropriate. * If the symbol has been defined with the fschar' request for the current font, use it. * Check all fonts in the order of appearance in the last special' call. * If the symbol has been defined with the schar' request, use it. * As a last resort, consult all fonts loaded up to now for special fonts and check them, starting with the lowest font number. Note that this can sometimes lead to surprising results since the fonts' line in the DESC' file often contains empty positions which are filled later on. For example, consider the following: fonts 3 0 0 FOO This mounts font foo' at font position 3. We assume that FOO' is a special font, containing glyph foo', and that no font has been loaded yet. The line .fspecial BAR BAZ makes font BAZ' special only if font BAR' is active. We further assume that BAZ' is really a special font, i.e., the font description file contains the special' keyword, and that it also contains glyph foo' with a special shape fitting to font BAR'. After executing fspecial', font BAR' is loaded at font position 1, and BAZ' at position 2. We now switch to a new font XXX', trying to access glyph foo' which is assumed to be missing. There are neither font-specific special fonts for XXX' nor any other fonts made special with the special' request, so gtroff' starts the search for special fonts in the list of already mounted fonts, with increasing font positions. Consequently, it finds BAZ' before FOO' even for XXX' which is not the intended behaviour. *Note Font Files::, and *Note Special Fonts::, for more details. The list of available symbols is device dependent; see the groff_char(7)' man page for a complete list of all glyphs. For example, say man -Tdvi groff_char > groff_char.dvi for a list using the default DVI fonts (not all versions of the man' program support the -T' option). If you want to use an additional macro package to change the used fonts, groff' must be called directly: groff -Tdvi -mec -man groff_char.7 > groff_char.dvi Glyph names not listed in groff_char(7) are derived algorithmically, using a simplified version of the Adobe Glyph List (AGL) algorithm which is described in http://partners.adobe.com/asn/tech/type/unicodegn.jsp'. The (frozen) set of glyph names which can't be derived algorithmically is called "groff glyph list (GGL)". * A glyph for Unicode character U+XXXX[X[X]] which is not a composite character will be named uXXXX[X[X]]'. X must be an uppercase hexadecimal digit. Examples: u1234', u008E', u12DB8'. The largest Unicode value is 0x10FFFF. There must be at least four X' digits; if necessary, add leading zeroes (after the u'). No zero padding is allowed for character codes greater than 0xFFFF. Surrogates (i.e., Unicode values greater than 0xFFFF represented with character codes from the surrogate area U+D800-U+DFFF) are not allowed too. * A glyph representing more than a single input character will be named u' COMPONENT1 _' COMPONENT2 _' COMPONENT3 ... Example: u0045_0302_0301'. For simplicity, all Unicode characters which are composites must be decomposed maximally (this is normalization form D in the Unicode standard); for example, u00CA_0301' is not a valid glyph name since U+00CA (LATIN CAPITAL LETTER E WITH CIRCUMFLEX) can be further decomposed into U+0045 (LATIN CAPITAL LETTER E) and U+0302 (COMBINING CIRCUMFLEX ACCENT). u0045_0302_0301' is thus the glyph name for U+1EBE, LATIN CAPITAL LETTER E WITH CIRCUMFLEX AND ACUTE. * groff maintains a table to decompose all algorithmically derived glyph names which are composites itself. For example, u0100' (LATIN LETTER A WITH MACRON) will be automatically decomposed into u0041_0304'. Additionally, a glyph name of the GGL is preferred to an algorithmically derived glyph name; groff also automatically does the mapping. Example: The glyph u0045_0302' will be mapped to ^E'. * glyph names of the GGL can't be used in composite glyph names; for example, ^E_u0301' is invalid. -- Escape: \(nm -- Escape: \[name] -- Escape: \[component1 component2 ...] Insert a symbol NAME (two-character name NM) or a composite glyph with component glyphs COMPONENT1, COMPONENT2, .... There is no special syntax for one-character names - the natural form \N' would collide with escapes.(1) (*note Using Symbols-Footnote-1::) If NAME is undefined, a warning of type char' is generated, and the escape is ignored. *Note Debugging::, for information about warnings. groff resolves \[...]' with more than a single component as follows: * Any component which is found in the GGL will be converted to the uXXXX' form. * Any component uXXXX' which is found in the list of decomposable glyphs will be decomposed. * The resulting elements are then concatenated with _' inbetween, dropping the leading u' in all elements but the first. No check for the existence of any component (similar to tr' request) will be done. Examples: \[A ho]' A' maps to u0041', ho' maps to u02DB', thus the final glyph name would be u0041_02DB'. Note this is not the expected result: The ogonek glyph ho' is a spacing ogonek, but for a proper composite a non-spacing ogonek (U+0328) is necessary. Looking into the file composite.tmac' one can find .composite ho u0328' which changes the mapping of ho' while a composite glyph name is constructed, causing the final glyph name to be u0041_0328'. \[^E u0301]' \[^E aa]' \[E a^ aa]' \[E ^ ']' ^E' maps to u0045_0302', thus the final glyph name is u0045_0302_0301' in all forms (assuming proper calls of the composite' request). It is not possible to define glyphs with names like A ho' within a groff font file. This is not really a limitation; instead, you have to define u0041_0328'. -- Escape: \C'xxx' Typeset the glyph named XXX.(2) (*note Using Symbols-Footnote-2::) Normally it is more convenient to use \[XXX]', but \C' has the advantage that it is compatible with newer versions of AT&T troff' and is available in compatibility mode. -- Request: .composite from to Map glyph name FROM to glyph name TO if it is used in \[...]' with more than one component. See above for examples. This mapping is based on glyph names only; no check for the existence of either glyph is done. A set of default mappings for many accents can be found in the file composite.tmac' which is loaded at start-up. -- Escape: \N'n' Typeset the glyph with code N in the current font (n' is *not* the input character code). The number N can be any non-negative decimal integer. Most devices only have glyphs with codes between 0 and 255; the Unicode output device uses codes in the range 0-65535. If the current font does not contain a glyph with that code, special fonts are _not_ searched. The \N' escape sequence can be conveniently used in conjunction with the char' request: .char \[phone] \f[ZD]\N'37' The code of each glyph is given in the fourth column in the font description file after the charset' command. It is possible to include unnamed glyphs in the font description file by using a name of ---'; the \N' escape sequence is the only way to use these. No kerning is applied to glyphs accessed with \N'. Some escape sequences directly map onto special glyphs. -- Escape: \' This is a backslash followed by the apostrophe character, ASCII character 0x27' (EBCDIC character 0x7D'). The same as \[aa]', the acute accent. -- Escape: \ This is a backslash followed by ASCII character 0x60' (EBCDIC character 0x79' usually). The same as \[ga]', the grave accent. -- Escape: \- This is the same as \[-]', the minus sign in the current font. -- Request: .cflags n c1 c2 ... Input characters and symbols have certain properties associated with it.(3) (*note Using Symbols-Footnote-3::) These properties can be modified with the cflags' request. The first argument is the sum of the desired flags and the remaining arguments are the characters or symbols to have those properties. It is possible to omit the spaces between the characters or symbols. 1' The character ends sentences (initially characters .?!' have this property). 2' Lines can be broken before the character (initially no characters have this property). 4' Lines can be broken after the character (initially the character -' and the symbols \[hy]' and \[em]' have this property). 8' The character overlaps horizontally if used as a horizontal line building element. Initially the symbols \[ul]', \[rn]', \[ru]', \[radicalex]', and \[sqrtex]' have this property. 16' The character overlaps vertically if used as vertical line building element. Initially symbol \[br]' has this property. 32' An end-of-sentence character followed by any number of characters with this property is treated as the end of a sentence if followed by a newline or two spaces; in other words the character is "transparent" for the purposes of end-of-sentence recognition - this is the same as having a zero space factor in TeX (initially characters "')]*' and the symbols \[dg]' and \[rq]' have this property). -- Request: .char g [string] -- Request: .fchar g [string] -- Request: .fschar f g [string] -- Request: .schar g [string] Define a new glyph G to be STRING (which can be empty).(4) (*note Using Symbols-Footnote-4::) Every time glyph G needs to be printed, STRING is processed in a temporary environment and the result is wrapped up into a single object. Compatibility mode is turned off and the escape character is set to \' while STRING is being processed. Any emboldening, constant spacing or track kerning is applied to this object rather than to individual characters in STRING. A glyph defined by these requests can be used just like a normal glyph provided by the output device. In particular, other characters can be translated to it with the tr' or trin' requests; it can be made the leader character by the lc' request; repeated patterns can be drawn with the glyph using the \l' and \L' escape sequences; words containing the glyph can be hyphenated correctly if the hcode' request is used to give the glyph's symbol a hyphenation code. There is a special anti-recursion feature: Use of g' within the glyph's definition is handled like normal characters and symbols not defined with char'. Note that the tr' and trin' requests take precedence if char' accesses the same symbol. .tr XY X => Y .char X Z X => Y .tr XX X => Z The fchar' request defines a fallback glyph: gtroff' only checks for glyphs defined with fchar' if it cannot find the glyph in the current font. gtroff' carries out this test before checking special fonts. fschar' defines a fallback glyph for font F: gtroff' checks for glyphs defined with fschar' after the list of fonts declared as font-specific special fonts with the fspecial' request, but before the list of fonts declared as global special fonts with the special' request. Finally, the schar' request defines a global fallback glyph: gtroff' checks for glyphs defined with schar' after the list of fonts declared as global special fonts with the special' request, but before the already mounted special fonts. *Note Using Symbols::, for a detailed description of the glyph searching mechanism in gtroff'. -- Request: .rchar c1 c2 ... -- Request: .rfschar f c1 c2 ... Remove the definitions of glyphs C1, C2, .... This undoes the effect of a char', fchar', or schar' request. It is possible to omit the whitespace between arguments. The request rfschar' removes glyph definitions defined with fschar' for glyph f. *Note Special Characters::. File: groff, Node: Using Symbols-Footnotes, Up: Using Symbols (1) Note that a one-character symbol is not the same as an input character, i.e., the character a' is not the same as \[a]'. By default, groff' defines only a single one-character symbol, \[-]'; it is usually accessed as \-'. On the other hand, gtroff' has the special feature that \[charXXX]' is the same as the input character with character code XXX. For example, \[char97]' is identical to the letter a' if ASCII encoding is active. (2) \C' is actually a misnomer since it accesses an output glyph. (3) Note that the output glyphs themselves don't have such properties. For gtroff', a glyph is a numbered box with a given width, depth, and height, nothing else. All manipulations with the cflags' request work on the input level. (4) char' is a misnomer since an output glyph is defined. File: groff, Node: Special Fonts, Next: Artificial Fonts, Prev: Using Symbols, Up: Fonts and Symbols 5.17.5 Special Fonts -------------------- Special fonts are those that gtroff' searches when it cannot find the requested glyph in the current font. The Symbol font is usually a special font. gtroff' provides the following two requests to add more special fonts. *Note Using Symbols::, for a detailed description of the glyph searching mechanism in gtroff'. Usually, only non-TTY devices have special fonts. -- Request: .special [s1 s2 ...] -- Request: .fspecial f [s1 s2 ...] Use the special' request to define special fonts. Initially, this list is empty. Use the fspecial' request to designate special fonts only when font F is active. Initially, this list is empty. Previous calls to special' or fspecial' are overwritten; without arguments, the particular list of special fonts is set to empty. Special fonts are searched in the order they appear as arguments. All fonts which appear in a call to special' or fspecial' are loaded. *Note Using Symbols::, for the exact search order of glyphs. File: groff, Node: Artificial Fonts, Next: Ligatures and Kerning, Prev: Special Fonts, Up: Fonts and Symbols 5.17.6 Artificial Fonts ----------------------- There are a number of requests and escapes for artificially creating fonts. These are largely vestiges of the days when output devices did not have a wide variety of fonts, and when nroff' and troff' were separate programs. Most of them are no longer necessary in GNU troff'. Nevertheless, they are supported. -- Escape: \H'height' -- Escape: \H'+height' -- Escape: \H'-height' -- Register: \n[.height] Change (increment, decrement) the height of the current font, but not the width. If HEIGHT is zero, restore the original height. Default scaling indicator is z'. The read-only number register .height' contains the font height as set by \H'. Currently, only the -Tps' device supports this feature. Note that \H' doesn't produce an input token in gtroff'. As a consequence, it can be used in requests like mc' (which expects a single character as an argument) to change the font on the fly: .mc \H'+5z'x\H'0' In compatibility mode, gtroff' behaves differently: If an increment or decrement is used, it is always taken relative to the current point size and not relative to the previously selected font height. Thus, .cp 1 \H'+5'test \H'+5'test prints the word test' twice with the same font height (five points larger than the current font size). -- Escape: \S'slant' -- Register: \n[.slant] Slant the current font by SLANT degrees. Positive values slant to the right. Only integer values are possible. The read-only number register .slant' contains the font slant as set by \S'. Currently, only the -Tps' device supports this feature. Note that \S' doesn't produce an input token in gtroff'. As a consequence, it can be used in requests like mc' (which expects a single character as an argument) to change the font on the fly: .mc \S'20'x\S'0' This request is incorrectly documented in the original UNIX troff manual; the slant is always set to an absolute value. -- Request: .ul [lines] The ul' request normally underlines subsequent lines if a TTY output device is used. Otherwise, the lines are printed in italics (only the term underlined' is used in the following). The single argument is the number of input lines to be underlined; with no argument, the next line is underlined. If LINES is zero or negative, stop the effects of ul' (if it was active). Requests and empty lines do not count for computing the number of underlined input lines, even if they produce some output like tl'. Lines inserted by macros (e.g. invoked by a trap) do count. At the beginning of ul', the current font is stored and the underline font is activated. Within the span of a ul' request, it is possible to change fonts, but after the last line affected by ul' the saved font is restored. This number of lines still to be underlined is associated with the current environment (*note Environments::). The underline font can be changed with the uf' request. The ul' request does not underline spaces. -- Request: .cu [lines] The cu' request is similar to ul' but underlines spaces as well (if a TTY output device is used). -- Request: .uf font Set the underline font (globally) used by ul' and cu'. By default, this is the font at position 2. FONT can be either a non-negative font position or the name of a font. -- Request: .bd font [offset] -- Request: .bd font1 font2 [offset] -- Register: \n[.b] Artificially create a bold font by printing each glyph twice, slightly offset. Two syntax forms are available. * Imitate a bold font unconditionally. The first argument specifies the font to embolden, and the second is the number of basic units, minus one, by which the two glyphs are offset. If the second argument is missing, emboldening is turned off. FONT can be either a non-negative font position or the name of a font. OFFSET is available in the .b' read-only register if a special font is active; in the bd' request, its default unit is u'. * Imitate a bold form conditionally. Embolden FONT1 by OFFSET only if font FONT2 is the current font. This command can be issued repeatedly to set up different emboldening values for different current fonts. If the second argument is missing, emboldening is turned off for this particular current font. This affects special fonts only (either set up with the special' command in font files or with the fspecial' request). -- Request: .cs font [width [em-size]] Switch to and from "constant glyph space mode". If activated, the width of every glyph is WIDTH/36 ems. The em size is given absolutely by EM-SIZE; if this argument is missing, the em value is taken from the current font size (as set with the ps' request) when the font is effectively in use. Without second and third argument, constant glyph space mode is deactivated. Default scaling indicator for EM-SIZE is z'; WIDTH is an integer. File: groff, Node: Ligatures and Kerning, Prev: Artificial Fonts, Up: Fonts and Symbols 5.17.7 Ligatures and Kerning ---------------------------- Ligatures are groups of characters that are run together, i.e, producing a single glyph. For example, the letters f' and i' can form a ligature fi' as in the word file'. This produces a cleaner look (albeit subtle) to the printed output. Usually, ligatures are not available in fonts for TTY output devices. Most POSTSCRIPT fonts support the fi and fl ligatures. The C/A/T typesetter that was the target of AT&T troff' also supported ff', ffi', and ffl' ligatures. Advanced typesetters or expert' fonts may include ligatures for ft' and ct', although GNU troff' does not support these (yet). Only the current font is checked for ligatures and kerns; neither special fonts nor entities defined with the char' request (and its siblings) are taken into account. -- Request: .lg [flag] -- Register: \n[.lg] Switch the ligature mechanism on or off; if the parameter is non-zero or missing, ligatures are enabled, otherwise disabled. Default is on. The current ligature mode can be found in the read-only number register .lg' (set to 1 or 2 if ligatures are enabled, 0 otherwise). Setting the ligature mode to 2 enables the two-character ligatures (fi, fl, and ff) and disables the three-character ligatures (ffi and ffl). "Pairwise kerning" is another subtle typesetting mechanism that modifies the distance between a glyph pair to improve readability. In most cases (but not always) the distance is decreased. Typewriter-like fonts and fonts for terminals where all glyphs have the same width don't use kerning. -- Request: .kern [flag] -- Register: \n[.kern] Switch kerning on or off. If the parameter is non-zero or missing, enable pairwise kerning, otherwise disable it. The read-only number register .kern' is set to 1 if pairwise kerning is enabled, 0 otherwise. If the font description file contains pairwise kerning information, glyphs from that font are kerned. Kerning between two glyphs can be inhibited by placing \&' between them: V\&A'. *Note Font File Format::. "Track kerning" expands or reduces the space between glyphs. This can be handy, for example, if you need to squeeze a long word onto a single line or spread some text to fill a narrow column. It must be used with great care since it is usually considered bad typography if the reader notices the effect. -- Request: .tkf f s1 n1 s2 n2 Enable track kerning for font F. If the current font is F the width of every glyph is increased by an amount between N1 and N2 (N1, N2 can be negative); if the current point size is less than or equal to S1 the width is increased by N1; if it is greater than or equal to S2 the width is increased by N2; if the point size is greater than or equal to S1 and less than or equal to S2 the increase in width is a linear function of the point size. The default scaling indicator is z' for S1 and S2, p' for N1 and N2. Note that the track kerning amount is added even to the rightmost glyph in a line; for large values it is thus recommended to increase the line length by the same amount to compensate it. Sometimes, when typesetting letters of different fonts, more or less space at such boundaries are needed. There are two escapes to help with this. -- Escape: \/ Increase the width of the preceding glyph so that the spacing between that glyph and the following glyph is correct if the following glyph is a roman glyph. For example, if an italic f' is immediately followed by a roman right parenthesis, then in many fonts the top right portion of the f' overlaps the top left of the right parenthesis. Use this escape sequence whenever an italic glyph is immediately followed by a roman glyph without any intervening space. This small amount of space is also called "italic correction". -- Escape: \, Modify the spacing of the following glyph so that the spacing between that glyph and the preceding glyph is correct if the preceding glyph is a roman glyph. Use this escape sequence whenever a roman glyph is immediately followed by an italic glyph without any intervening space. In analogy to above, this space could be called "left italic correction", but this term isn't used widely. -- Escape: \& Insert a zero-width character, which is invisible. Its intended use is to stop interaction of a character with its surrounding. * It prevents the insertion of extra space after an end-of-sentence character. Test. Test. => Test. Test. Test.\& Test. => Test. Test. * It prevents interpretation of a control character at the beginning of an input line. .Test => warning: Test' not defined \&.Test => .Test * It prevents kerning between two glyphs. * It is needed to map an arbitrary character to nothing in the tr' request (*note Character Translations::). -- Escape:$$ This escape is similar to \&' except that it behaves like a character declared with the cflags' request to be transparent for the purposes of an end-of-sentence character. Its main usage is in macro definitions to protect against arguments starting with a control character. .de xxx \)\\$1
..
.de yyy
\&\\$1 .. This is a test.\c .xxx ' This is a test. =>This is a test.' This is a test. This is a test.\c .yyy ' This is a test. =>This is a test.' This is a test. File: groff, Node: Sizes, Next: Strings, Prev: Fonts and Symbols, Up: gtroff Reference 5.18 Sizes ========== gtroff' uses two dimensions with each line of text, type size and vertical spacing. The "type size" is approximately the height of the tallest glyph.(1) (*note Sizes-Footnote-1::) "Vertical spacing" is the amount of space gtroff' allows for a line of text; normally, this is about 20% larger than the current type size. Ratios smaller than this can result in hard-to-read text; larger than this, it spreads the text out more vertically (useful for term papers). By default, gtroff' uses 10 point type on 12 point spacing. The difference between type size and vertical spacing is known, by typesetters, as "leading" (this is pronounced ledding'). * Menu: * Changing Type Sizes:: * Fractional Type Sizes:: File: groff, Node: Sizes-Footnotes, Up: Sizes (1) This is usually the parenthesis. Note that in most cases the real dimensions of the glyphs in a font are _not_ related to its type size! For example, the standard POSTSCRIPT font families Times Roman', Helvetica', and Courier' can't be used together at 10pt; to get acceptable output, the size of Helvetica' has to be reduced by one point, and the size of Courier' must be increased by one point. File: groff, Node: Changing Type Sizes, Next: Fractional Type Sizes, Prev: Sizes, Up: Sizes 5.18.1 Changing Type Sizes -------------------------- -- Request: .ps [size] -- Request: .ps +size -- Request: .ps -size -- Escape: \ssize -- Register: \n[.s] Use the ps' request or the \s' escape to change (increase, decrease) the type size (in points). Specify SIZE as either an absolute point size, or as a relative change from the current size. The size 0, or no argument, goes back to the previous size. Default scaling indicator of size' is z'. If size' is zero or negative, it is set to 1u. The read-only number register .s' returns the point size in points as a decimal fraction. This is a string. To get the point size in scaled points, use the .ps' register instead. .s' is associated with the current environment (*note Environments::). snap, snap, .ps +2 grin, grin, .ps +2 wink, wink, \s+2nudge, nudge,\s+8 say no more! .ps 10 The \s' escape may be called in a variety of ways. Much like other escapes there must be a way to determine where the argument ends and the text begins. Any of the following forms are valid: \sN' Set the point size to N points. N must be either 0 or in the range 4 to 39. \s+N' \s-N' Increase or decrease the point size by N points. N must be exactly one digit. \s(NN' Set the point size to NN points. NN must be exactly two digits. \s+(NN' \s-(NN' \s(+NN' \s(-NN' Increase or decrease the point size by NN points. NN must be exactly two digits. Note that \s' doesn't produce an input token in gtroff'. As a consequence, it can be used in requests like mc' (which expects a single character as an argument) to change the font on the fly: .mc \s[20]x\s[0] *Note Fractional Type Sizes::, for yet another syntactical form of using the \s' escape. -- Request: .sizes s1 s2 ... sn [0] Some devices may only have certain permissible sizes, in which case gtroff' rounds to the nearest permissible size. The DESC' file specifies which sizes are permissible for the device. Use the sizes' request to change the permissible sizes for the current output device. Arguments are in scaled points; the sizescale' line in the DESC' file for the output device provides the scaling factor. For example, if the scaling factor is 1000, then the value 12000 is 12 points. Each argument can be a single point size (such as 12000'), or a range of sizes (such as 4000-72000'). You can optionally end the list with a zero. -- Request: .vs [space] -- Request: .vs +space -- Request: .vs -space -- Register: \n[.v] Change (increase, decrease) the vertical spacing by SPACE. The default scaling indicator is p'. If vs' is called without an argument, the vertical spacing is reset to the previous value before the last call to vs'. gtroff' creates a warning of type range' if SPACE is negative; the vertical spacing is then set to smallest positive value, the vertical resolution (as given in the .V' register). Note that .vs 0' isn't saved in a diversion since it doesn't result in a vertical motion. You explicitly have to repeat this command before inserting the diversion. The read-only number register .v' contains the current vertical spacing; it is associated with the current environment (*note Environments::). The effective vertical line spacing consists of four components. Breaking a line causes the following actions (in the given order). * Move the current point vertically by the "extra pre-vertical line space". This is the minimum value of all \x' escapes with a negative argument in the current output line. * Move the current point vertically by the vertical line spacing as set with the vs' request. * Output the current line. * Move the current point vertically by the "extra post-vertical line space". This is the maximum value of all \x' escapes with a positive argument in the line which has just been output. * Move the current point vertically by the "post-vertical line spacing" as set with the pvs' request. It is usually better to use vs' or pvs' instead of ls' to produce double-spaced documents: vs' and pvs' have a finer granularity for the inserted vertical space compared to ls'; furthermore, certain preprocessors assume single-spacing. *Note Manipulating Spacing::, for more details on the \x' escape and the ls' request. -- Request: .pvs [space] -- Request: .pvs +space -- Request: .pvs -space -- Register: \n[.pvs] Change (increase, decrease) the post-vertical spacing by SPACE. The default scaling indicator is p'. If pvs' is called without an argument, the post-vertical spacing is reset to the previous value before the last call to pvs'. gtroff' creates a warning of type range' if SPACE is zero or negative; the vertical spacing is then set to zero. The read-only number register .pvs' contains the current post-vertical spacing; it is associated with the current environment (*note Environments::). File: groff, Node: Fractional Type Sizes, Prev: Changing Type Sizes, Up: Sizes 5.18.2 Fractional Type Sizes ---------------------------- A "scaled point" is equal to 1/SIZESCALE points, where SIZESCALE is specified in the DESC' file (1 by default). There is a new scale indicator z' which has the effect of multiplying by SIZESCALE. Requests and escape sequences in gtroff' interpret arguments that represent a point size as being in units of scaled points, but they evaluate each such argument using a default scale indicator of z'. Arguments treated in this way are the argument to the ps' request, the third argument to the cs' request, the second and fourth arguments to the tkf' request, the argument to the \H' escape sequence, and those variants of the \s' escape sequence that take a numeric expression as their argument (see below). For example, suppose SIZESCALE is 1000; then a scaled point is equivalent to a millipoint; the request .ps 10.25' is equivalent to .ps 10.25z' and thus sets the point size to 10250 scaled points, which is equal to 10.25 points. gtroff' disallows the use of the z' scale indicator in instances where it would make no sense, such as a numeric expression whose default scale indicator was neither u' nor z'. Similarly it would make no sense to use a scaling indicator other than z' or u' in a numeric expression whose default scale indicator was z', and so gtroff' disallows this as well. There is also new scale indicator s' which multiplies by the number of units in a scaled point. So, for example, \n[.ps]s' is equal to 1m'. Be sure not to confuse the s' and z' scale indicators. -- Register: \n[.ps] A read-only number register returning the point size in scaled points. .ps' is associated with the current environment (*note Environments::). -- Register: \n[.psr] -- Register: \n[.sr] The last-requested point size in scaled points is contained in the .psr' read-only number register. The last requested point size in points as a decimal fraction can be found in .sr'. This is a string-valued read-only number register. Note that the requested point sizes are device-independent, whereas the values returned by the .ps' and .s' registers are not. For example, if a point size of 11pt is requested, and a sizes' request (or a sizescale' line in a DESC' file) specifies 10.95pt instead, this value is actually used. Both registers are associated with the current environment (*note Environments::). The \s' escape has the following syntax for working with fractional type sizes: \s[N]' \s'N'' Set the point size to N scaled points; N is a numeric expression with a default scale indicator of z'. \s[+N]' \s[-N]' \s+[N]' \s-[N]' \s'+N'' \s'-N'' \s+'N'' \s-'N'' Increase or or decrease the point size by N scaled points; N is a numeric expression with a default scale indicator of z'. *Note Font Files::. File: groff, Node: Strings, Next: Conditionals and Loops, Prev: Sizes, Up: gtroff Reference 5.19 Strings ============ gtroff' has string variables, which are entirely for user convenience (i.e. there are no built-in strings exept .T', but even this is a read-write string variable). -- Request: .ds name [string] -- Request: .ds1 name [string] -- Escape: \*n -- Escape: \*(nm -- Escape: \*[name arg1 arg2 ...] Define and access a string variable NAME (one-character name N, two-character name NM). If NAME already exists, ds' overwrites the previous definition. Only the syntax form using brackets can take arguments which are handled identically to macro arguments; the single exception is that a closing bracket as an argument must be enclosed in double quotes. *Note Request and Macro Arguments::, and *Note Parameters::. Example: .ds foo a \\$1 test
.
This is \*[foo nice].
=> This is a nice test.

The \*' escape "interpolates" (expands in-place) a
previously-defined string variable.  To be more precise, the stored
string is pushed onto the input stack which is then parsed by
gtroff'.  Similar to number registers, it is possible to nest
strings, i.e. string variables can be called within string
variables.

If the string named by the \*' escape does not exist, it is
defined as empty, and a warning of type mac' is emitted (see
*Note Debugging::, for more details).

*Caution:* Unlike other requests, the second argument to the ds'
request takes up the entire line including trailing spaces.  This
means that comments on a line with such a request can introduce
unwanted space into a string.

.ds UX \s-1UNIX\s0\u\s-3tm\s0\d \" UNIX trademark

Instead the comment should be put on another line or have the
comment escape adjacent with the end of the string.

To produce leading space the string can be started with a double
quote.  No trailing quote is needed; in fact, any trailing quote is

.ds sign "           Yours in a white wine sauce,

Strings are not limited to a single line of text.  A string can
span several lines by escaping the newlines with a backslash.  The
resulting string is stored _without_ the newlines.

.ds foo lots and lots \
of text are on these \
next several lines

It is not possible to have real newlines in a string.  To put a
single double quote character into a string, use two consecutive
double quote characters.

The ds1' request turns off compatibility mode while interpreting
a string.  To be more precise, a "compatibility save" input token
is inserted at the beginning of  the string, and a "compatibility
restore" input token at the end.

.nr xxx 12345
.ds aa The value of xxx is \\n[xxx].
.ds1 bb The value of xxx ix \\n[xxx].
.
.cp 1
.
\*(aa
=> warning: number register [' not defined
=> The value of xxx is 0xxx].
\*(bb
=> The value of xxx ix 12345.

Strings, macros, and diversions (and boxes) share the same name
space.  Internally, even the same mechanism is used to store them.
This has some interesting consequences.  For example, it is
possible to call a macro with string syntax and vice versa.

.de xxx
a funny test.
..
This is \*[xxx]
=> This is a funny test.

.ds yyy a funny test
This is
.yyy
=> This is a funny test.

Diversions and boxes can be also called with string syntax.

Another consequence is that you can copy one-line diversions or
boxes to a string.

.di xxx
a \fItest\fR
.br
.di
.ds yyy This is \*[xxx]\c
\*[yyy].
=> This is a test.

As the previous example shows, it is possible to store formatted
output in strings.  The \c' escape prevents the insertion of an
additional blank line in the output.

Copying diversions longer than a single output line produces
unexpected results.

.di xxx
a funny
.br
test
.br
.di
.ds yyy This is \*[xxx]\c
\*[yyy].
=> test This is a funny.

Usually, it is not predictable whether a diversion contains one or
more output lines, so this mechanism should be avoided.  With UNIX
troff', this was the only solution to strip off a final newline
from a diversion.  Another disadvantage is that the spaces in the
copied string are already formatted, making them unstretchable.
This can cause ugly results.

A clean solution to this problem is available in GNU troff',
using the requests chop' to remove the final newline of a
diversion, and unformat' to make the horizontal spaces
stretchable again.

.box xxx
a funny
.br
test
.br
.box
.chop xxx
.unformat xxx
This is \*[xxx].
=> This is a funny test.

-- Request: .as name [string]
-- Request: .as1 name [string]
The as' request is similar to ds' but appends STRING to the
string stored as NAME instead of redefining it.  If NAME doesn't
exist yet, it is created.

.as sign " with shallots, onions and garlic,

The as1' request is similar to as', but compatibility mode is
switched off while the appended string is interpreted.  To be more
precise, a "compatibility save" input token is inserted at the
beginning of the appended string, and a "compatibility restore"
input token at the end.

Rudimentary string manipulation routines are given with the next two
requests.

-- Request: .substring str n1 [n2]
Replace the string named STR with the substring defined by the
indices N1 and N2.  The first character in the string has index 0.
If N2 is omitted, it is taken to be equal to the string's length.
If the index value N1 or N2 is negative, it is counted from the
end of the string, going backwards: The last character has
index -1, the character before the last character has index -2,
etc.

.ds xxx abcdefgh
.substring xxx 1 -4
\*[xxx]
=> bcde

-- Request: .length reg str
Compute the number of characters of STR and return it in the
number register REG.  If REG doesn't exist, it is created.  str'

.ds xxx abcd\h'3i'efgh
.length yyy \*[xxx]
\n[yyy]
=> 14

-- Request: .rn xx yy
Rename the request, macro, diversion, or string XX to YY.

-- Request: .rm xx
Remove the request, macro, diversion, or string XX.  gtroff'
treats subsequent invocations as if the object had never been
defined.

-- Request: .als new old
Create an alias named NEW for the request, string, macro, or
diversion object named OLD.  The new name and the old name are
exactly equivalent (it is similar to a hard rather than a soft
link). If OLD is undefined, gtroff' generates a warning of type
mac' and ignores the request.

-- Request: .chop xx
Remove (chop) the last character from the macro, string, or
diversion named XX.  This is useful for removing the newline from
the end of diversions that are to be interpolated as strings.
This command can be used repeatedly; see *Note Gtroff Internals::,
for details on nodes inserted additionally by gtroff'.

File: groff,  Node: Conditionals and Loops,  Next: Writing Macros,  Prev: Strings,  Up: gtroff Reference

5.20 Conditionals and Loops
===========================

* Operators in Conditionals::
* if-else::
* while::

File: groff,  Node: Operators in Conditionals,  Next: if-else,  Prev: Conditionals and Loops,  Up: Conditionals and Loops

5.20.1 Operators in Conditionals
--------------------------------

In if' and while' requests, there are several more operators
available:

e'
o'
True if the current page is even or odd numbered (respectively).

n'
True if the document is being processed in nroff mode (i.e., the
.nroff' command has been issued).

t'
True if the document is being processed in troff mode (i.e., the
.troff' command has been issued).

v'
Always false.  This condition is for compatibility with other
troff' versions only (identifying a -Tversatec' device).

'XXX'YYY''
True if the string XXX is equal to the string YYY.  Other
characters can be used in place of the single quotes; the same set
of delimiters as for the \D' escape is used (*note Escapes::).
gtroff' formats the strings before being compared:

.ie "|"\fR|\fP" \
true
.el \
false
=> true

The resulting motions, glyph sizes, and fonts have to match,(1)
(*note Operators in Conditionals-Footnote-1::) and not the
individual motion, size, and font requests.  In the previous
example, |' and \fR|\fP' both result in a roman |' glyph with
the same point size and at the same location on the page, so the
strings are equal.  If .ft I' had been added before the .ie',
the result would be "false" because (the first) |' produces an
italic |' rather than a roman one.

r XXX'
True if there is a number register named XXX.

d XXX'
True if there is a string, macro, diversion, or request named XXX.

m XXX'
True if there is a color named XXX.

c G'
True if there is a glyph G available(2) (*note Operators in
Conditionals-Footnote-2::); G is either an ASCII character or a
special character (\(GG' or \[GGG]'); the condition is also true
if G has been defined by the char' request.

F FONT'
True if a font named FONT exists.  FONT is handled as if it was
opened with the ft' request (this is, font translation and styles
are applied), without actually mounting it.

This test doesn't load the complete font but only its header to
verify its validity.

S STYLE'
True if style STYLE has been registered.  Font translation is
applied.

Note that these operators can't be combined with other operators like
:' or &'; only a leading !' (without whitespace between the
exclamation mark and the operator) can be used to negate the result.

.nr xxx 1
.ie !r xxx \
true
.el \
false
=> false

A whitespace after !' always evaluates to zero (this bizarre
behaviour is due to compatibility with UNIX troff').

.nr xxx 1
.ie ! r xxx \
true
.el \
false
=> r xxx true

It is possible to omit the whitespace before the argument to the
r', d', and c' operators.

*Note Expressions::.

File: groff,  Node: Operators in Conditionals-Footnotes,  Up: Operators in Conditionals

(1) The created output nodes must be identical.  *Note Gtroff
Internals::.

(2) The name of this conditional operator is a misnomer since it
tests names of output glyphs.

File: groff,  Node: if-else,  Next: while,  Prev: Operators in Conditionals,  Up: Conditionals and Loops

5.20.2 if-else
--------------

gtroff' has if-then-else constructs like other languages, although the
formatting can be painful.

-- Request: .if expr anything
Evaluate the expression EXPR, and executes ANYTHING (the remainder
of the line) if EXPR evaluates to a value greater than zero
(true).  ANYTHING is interpreted as though it was on a line by
itself (except that leading spaces are swallowed).  *Note

.nr xxx 1
.nr yyy 2
.if ((\n[xxx] == 1) & (\n[yyy] == 2)) true
=> true

-- Request: .nop anything
Executes ANYTHING.  This is similar to .if 1'.

-- Request: .ie expr anything
-- Request: .el anything
Use the ie' and el' requests to write an if-then-else.  The
first request is the if' part and the latter is the else' part.

.ie n .ls 2 \" double-spacing in nroff
.el   .ls 1 \" single-spacing in troff

-- Escape: \{
-- Escape: \}
In many cases, an if (or if-else) construct needs to execute more
than one request.  This can be done using the \{' and \}'
escapes.  The following example shows the possible ways to use
these escapes (note the position of the opening and closing
braces).

.ie t \{\
.    ds lq 
.    ds rq ''
.\}
.el \
.\{\
.    ds lq "
.    ds rq "\}

*Note Expressions::.

File: groff,  Node: while,  Prev: if-else,  Up: Conditionals and Loops

5.20.3 while
------------

gtroff' provides a looping construct using the while' request, which
is used much like the if' (and related) requests.

-- Request: .while expr anything
Evaluate the expression EXPR, and repeatedly execute ANYTHING (the
remainder of the line) until EXPR evaluates to 0.

.nr a 0 1
.while (\na < 9) \{\
\n+a,
.\}
\n+a
=> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Some remarks.

* The body of a while' request is treated like the body of a
de' request: gtroff' temporarily stores it in a macro which
is deleted after the loop has been exited.  It can
considerably slow down a macro if the body of the while'
request (within the macro) is large.  Each time the macro is
executed, the while' body is parsed and stored again as a
temporary macro.

.de xxx
.  nr num 10
.  while (\\n[num] > 0) \{\
.    \" many lines of code
.    nr num -1
.  \}
..

The traditional and ofter better solution (UNIX troff'
doesn't have the while' request) is to use a recursive macro
instead which is parsed only once during its definition.

.de yyy
.  if (\\n[num] > 0) \{\
.    \" many lines of code
.    nr num -1
.    yyy
.  \}
..
.
.de xxx
.  nr num 10
.  yyy
..

Note that the number of available recursion levels is set
to 1000 (this is a compile-time constant value of gtroff').

* The closing brace of a while' body must end a line.

.if 1 \{\
.  nr a 0 1
.  while (\n[a] < 10) \{\
.    nop \n+[a]
.\}\}
=> unbalanced \{ \}

-- Request: .break
Break out of a while' loop.  Be sure not to confuse this with the
br' request (causing a line break).

-- Request: .continue
Finish the current iteration of a while' loop, immediately
restarting the next iteration.

*Note Expressions::.

File: groff,  Node: Writing Macros,  Next: Page Motions,  Prev: Conditionals and Loops,  Up: gtroff Reference

5.21 Writing Macros
===================

A "macro" is a collection of text and embedded commands which can be
invoked multiple times.  Use macros to define common operations.

-- Request: .de name [end]
-- Request: .de1 name [end]
-- Request: .dei name [end]
-- Request: .dei1 name [end]
Define a new macro named NAME.  gtroff' copies subsequent lines
(starting with the next one) into an internal buffer until it
encounters the line ..' (two dots).  The optional second argument
to de' changes this to a macro to .END'.

There can be whitespace after the first dot in the line containing
the ending token (either .' or macro END').

Here a small example macro called P' which causes a break and
inserts some vertical space.  It could be used to separate
paragraphs.

.de P
.  br
.  sp .8v
..

The following example defines a macro within another.  Remember
that expansion must be protected twice; once for reading the macro
and once for executing.

\# a dummy macro to avoid a warning
.de end
..
.
.de foo
.  de bar end
.    nop \f[B]Hallo \\\\$1!\f[] . end .. . .foo .bar Joe => Hallo Joe! Since \f' has no expansion, it isn't necessary to protect its backslash. Had we defined another macro within bar' which takes a parameter, eight backslashes would be necessary before $1'.

The de1' request turns off compatibility mode while executing the
macro.  On entry, the current compatibility mode is saved and
restored at exit.

.nr xxx 12345
.
.de aa
The value of xxx is \\n[xxx].
..
.de1 bb
The value of xxx ix \\n[xxx].
..
.
.cp 1
.
.aa
=> warning: number register [' not defined
=> The value of xxx is 0xxx].
.bb
=> The value of xxx ix 12345.

The dei' request defines a macro indirectly.  That is, it expands
strings whose names are NAME or END before performing the append.

This:

.ds xx aa
.ds yy bb
.dei xx yy

is equivalent to:

.de aa bb

The dei1' request is similar to dei' but with compatibility mode
switched off during execution of the defined macro.

If compatibility mode is on, de' (and dei') behave similar to
de1' (and dei1'): A compatibility save' token is inserted at
the beginning, and a compatibility restore' token at the end, with
compatibility mode switched on during execution.  *Note Gtroff
on and off in a single document.

Using trace.tmac', you can trace calls to de' and de1'.

Note that macro identifiers are shared with identifiers for
strings and diversions.

-- Request: .am name [end]
-- Request: .am1 name [end]
-- Request: .ami name [end]
-- Request: .ami1 name [end]
Works similarly to de' except it appends onto the macro named
NAME.  So, to make the previously defined P' macro actually do
existing macro like this:

.am P
.ti +5n
..

The am1' request turns off compatibility mode while executing the
appended macro piece.  To be more precise, a "compatibility save"
input token is inserted at the beginning of the appended code, and
a "compatibility restore" input token at the end.

The ami' request appends indirectly, meaning that gtroff'
expands strings whose names are NAME or END before performing the
append.

The ami1' request is similar to ami' but compatibility mode is
switched off during execution of the defined macro.

Using trace.tmac', you can trace calls to am' and am1'.

*Note Strings::, for the als' request to rename a macro.

The de', am', di', da', ds', and as' requests (together with
its variants) only create a new object if the name of the macro,
diversion or string diversion is currently undefined or if it is
defined to be a request; normally they modify the value of an existing
object.

-- Request: .return [anything]
Exit a macro, immediately returning to the caller.

If called with an argument, exit twice, namely the current macro
and the macro one level higher.  This is used to define a wrapper
macro for return' in trace.tmac'.

* Copy-in Mode::
* Parameters::

File: groff,  Node: Copy-in Mode,  Next: Parameters,  Prev: Writing Macros,  Up: Writing Macros

5.21.1 Copy-in Mode
-------------------

When gtroff' reads in the text for a macro, string, or diversion, it
copies the text (including request lines, but excluding escapes) into
an internal buffer.  Escapes are converted into an internal form,
except for \n', \$', \*', \\' and \<RET>' which are evaluated and inserted into the text where the escape was located. This is known as "copy-in" mode or "copy" mode. What this means is that you can specify when these escapes are to be evaluated (either at copy-in time or at the time of use) by insulating the escapes with an extra backslash. Compare this to the \def' and \edef' commands in TeX. The following example prints the numbers 20 and 10: .nr x 20 .de y .nr x 10 \&\nx \&\\nx .. .y File: groff, Node: Parameters, Prev: Copy-in Mode, Up: Writing Macros 5.21.2 Parameters ----------------- The arguments to a macro or string can be examined using a variety of escapes. -- Register: \n[.$]
The number of arguments passed to a macro or string.  This is a

Note that the shift' request can change its value.

Any individual argument can be retrieved with one of the following
escapes:

-- Escape: \$n -- Escape: \$(nn
-- Escape: \$[nnn] Retrieve the Nth, NNth or NNNth argument. As usual, the first form only accepts a single number (larger than zero), the second a two-digit number (larger or equal to 10), and the third any positive integer value (larger than zero). Macros and strings can have an unlimited number of arguments. Note that due to copy-in mode, use two backslashes on these in actual use to prevent interpolation until the macro is actually invoked. -- Request: .shift [n] Shift the arguments 1 position, or as many positions as specified by its argument. After executing this request, argument I becomes argument I-N; arguments 1 to N are no longer available. Shifting by negative amounts is currently undefined. The register .$' is adjusted accordingly.

-- Escape: \$* -- Escape: \$@
In some cases it is convenient to use all of the arguments at once
(for example, to pass the arguments along to another macro).  The
\$*' escape concatenates all the arguments separated by spaces. A similar escape is \$@', which concatenates all the arguments with
each surrounded by double quotes, and separated by spaces.  If not
in compatibility mode, the input level of double quotes is
preserved (see *Note Request and Macro Arguments::).

-- Escape: \$0 The name used to invoke the current macro. The als' request can make a macro have more than one name. .de generic-macro . ... . if \\n[error] \{\ . tm \\$0: Houston, we have a problem.
.    return
.  \}
..
.
.als foo generic-macro
.als bar generic-macro

*Note Request and Macro Arguments::.

File: groff,  Node: Page Motions,  Next: Drawing Requests,  Prev: Writing Macros,  Up: gtroff Reference

5.22 Page Motions
=================

*Note Manipulating Spacing::, for a discussion of the main request for
vertical motion, sp'.

-- Request: .mk [reg]
-- Request: .rt [dist]
The request mk' can be used to mark a location on a page, for
movement to later.  This request takes a register name as an
argument in which to store the current page location.  With no
argument it stores the location in an internal register.  The
results of this can be used later by the rt' or the sp' request
(or the \v' escape).

The rt' request returns _upwards_ to the location marked with the
last mk' request.  If used with an argument, return to a position
which distance from the top of the page is DIST (no previous call
to mk' is necessary in this case).  Default scaling indicator is
v'.

Here a primitive solution for a two-column macro.

.nr column-length 1.5i
.nr column-gap 4m
.nr bottom-margin 1m
.

.de 2c
.  br
.  mk
.  ll \\n[column-length]u
.  wh -\\n[bottom-margin]u 2c-trap
.  nr right-side 0
..
.

.de 2c-trap
.  ie \\n[right-side] \{\
.    nr right-side 0
.    po -(\\n[column-length]u + \\n[column-gap]u)
.    \" remove trap
.    wh -\\n[bottom-margin]u
.  \}
.  el \{\
.    \" switch to right side
.    nr right-side 1
.    po +(\\n[column-length]u + \\n[column-gap]u)
.    rt
.  \}
..
.

.pl 1.5i
.ll 4i
This is a small test which shows how the
rt request works in combination with mk.

.2c
Starting here, text is typeset in two columns.
Note that this implementation isn't robust
and thus not suited for a real two-column
macro.

Result:

This is a small test which shows how the
rt request works in combination with mk.

Starting  here,    isn't    robust
text is typeset    and   thus  not
in two columns.    suited  for   a
Note that  this    real two-column
implementation     macro.

The following escapes give fine control of movements about the page.

-- Escape: \v'e'
Move vertically, usually from the current location on the page (if
no absolute position operator |' is used).  The argument E
specifies the distance to move; positive is downwards and negative
upwards.  The default scaling indicator for this escape is v'.
Beware, however, that gtroff' continues text processing at the
point where the motion ends, so you should always balance motions
to avoid interference with text processing.

\v' doesn't trigger a trap.  This can be quite useful; for
example, consider a page bottom trap macro which prints a marker
in the margin to indicate continuation of a footnote or something
similar.

There are some special-case escapes for vertical motion.

-- Escape: \r
Move upwards 1v.

-- Escape: \u
Move upwards .5v.

-- Escape: \d
Move down .5v.

-- Escape: \h'e'
Move horizontally, usually from the current location (if no
absolute position operator |' is used).  The expression E
indicates how far to move: positive is rightwards and negative
leftwards.  The default scaling indicator for this escape is m'.

This horizontal space is not discarded at the end of a line.  To
insert discardable space of a certain length use the ss' request.

There are a number of special-case escapes for horizontal motion.

-- Escape: \<SP>
An unbreakable and unpaddable (i.e. not expanded during filling)
space.  (Note: This is a backslash followed by a space.)

-- Escape: \~
An unbreakable space that stretches like a normal inter-word space

-- Escape: \|
A 1/6th em space.  Ignored for TTY output devices (rounded to
zero).

-- Escape: \^
A 1/12th em space.  Ignored for TTY output devices (rounded to
zero).

-- Escape: \0
A space the size of a digit.

The following string sets the TeX logo:

.ds TeX T\h'-.1667m'\v'.224m'E\v'-.224m'\h'-.125m'X

-- Escape: \w'text'
-- Register: \n[st]
-- Register: \n[sb]
-- Register: \n[rst]
-- Register: \n[rsb]
-- Register: \n[ct]
-- Register: \n[ssc]
-- Register: \n[skw]
Return the width of the specified TEXT in basic units.  This
allows horizontal movement based on the width of some arbitrary
text (e.g. given as an argument to a macro).

The length of the string abc' is \w'abc'u.
=> The length of the string abc' is 72u.

Font changes may occur in TEXT which don't affect current settings.

After use, \w' sets several registers:

st'
sb'
The highest and lowest point of the baseline, respectively,
in TEXT.

rst'
rsb'
Like the st' and sb' registers, but takes account of the
heights and depths of glyphs.  With other words, this gives
the highest and lowest point of TEXT.  Values below the
baseline are negative.

ct'
Defines the kinds of glyphs occurring in TEXT:

0
only short glyphs, no descenders or tall glyphs.

1
at least one descender.

2
at least one tall glyph.

3
at least one each of a descender and a tall glyph.

ssc'
The amount of horizontal space (possibly negative) that
should be added to the last glyph before a subscript.

skw'
How far to right of the center of the last glyph in the \w'
argument, the center of an accent from a roman font should be
placed over that glyph.

-- Escape: \kp
-- Escape: \k(ps
-- Escape: \k[position]
Store the current horizontal position in the _input_ line in
number register with name POSITION (one-character name P,
beginning of a string for highlighting or other decoration.

-- Register: \n[hp]
The current horizontal position at the input line.

-- Register: \n[.k]
A read-only number register containing the current horizontal
output position (relative to the current indentation).

-- Escape: \o'abc'
Overstrike glyphs A, B, C, ...; the glyphs are centered, and the
resulting spacing is the largest width of the affected glyphs.

-- Escape: \zg
Print glyph G with zero width, i.e., without spacing.  Use this to
overstrike glyphs left-aligned.

-- Escape: \Z'anything'
Print ANYTHING, then restore the horizontal and vertical position.
The argument may not contain tabs or leaders.

The following is an example of a strike-through macro:

.de ST
.nr ww \w'\\$1' \Z@\v'-.25m'\l'\\n[ww]u'@\\$1
..
.
This is
.ST "a test"
an actual emergency!

Local Variables:
coding: iso-8859-1
End:
`