<?xml version="1.0" standalone="no"?>
<!DOCTYPE book [
<!ENTITY chap1 SYSTEM "chap1.xml">
<!ENTITY chap2 SYSTEM "chap2.xml">
<!ENTITY chap3 SYSTEM "chap3.xml">
<!ENTITY appa SYSTEM "appa.xml">
<!ENTITY appb SYSTEM "appb.xml">
]>
<book xmlns="http://docbook.org/ns/docbook" version="5.0">
<title>My First Book</title>
&chap1;
&chap2;
&chap3;
&appa;
&appb;
</book>
