<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V3.1//EN"> <book> <chapter><title>Required Chapter</title> <para> At least one chapter, reference, part, or article is required in a book. </para> </chapter> <appendix><title>Demonstration Appendix</title> <para> This appendix demonstrates an appendix in a book. It has the same broad content model as a chapter. </para> </appendix> </book>