Docbook xi:include

Question

I am trying to create a docbook. I have created a main XML book and inside it I am using <xi:include> to add different chapters.

I am following DocBook XSL: The Complete Guide / Using XInclude to create book and chapter files.

Here is my main XML file book1.xml.

<?xml version="1.0"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
                      "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<book>
  <title>MAIN NOTES</title>
  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="CH1.xml" />
</book>

And here is my chapter1 (CH1.xml).

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
                         "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<chapter id="CH1">
  <title>Chapter 1</title>
  <para>This is Test</para>
</chapter>

Now when I am validating these XML files, CH1.xml is ok. But I am always getting

No Declaration found for element "xi:include"

for book1.xml. What am I missing here? Please help.

Answer 1

How to make DTD validation work when using XInclude is described in another section of "DocBook XSL: The Complete Guide": http://www.sagehill.net/docbookxsl/ValidXinclude.html.

In short, there are two alternatives:

1. Validate after XInclude processing. With xmllint, this can be done using this command: xmllint --xinclude --postvalid book1.xml
2. Customize the DTD to include the xi:include element.