Which added the XInclude mechanism to the BITS Tag Set, so that books and book parts can be managed as separate files and “included” as needed into a final document.
For detains concerning the use of XInclude, see http://www.w3.org/TR/xinclude/.
The optional <xi:fallback> child can be used to specify alternative content when the resource to be included was not found.
<!ELEMENT xi:include %include-model; >
(xi:fallback?)
<xi:fallback> XInclude Fallback, zero or one
<body>, <book-back>, <book-body>, <book-part-wrapper>, <front-matter>
<book
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:xlink="http://www.w3.org/1999/xlink"
dtd-version="1.0"
xml:lang="en">
<book-meta>...</book-meta>
<!-- ===== Front Matter (Narrative Content) ===== -->
<front-matter>
<!-- Dedication -->
<xi:include href="bits-book-part4.xml"
xmlns:xi="http://www.w3.org/2001/XInclude"></xi:include>
...
</front-matter>
<!-- =============== Body Matter (Content) =========== -->
<book-body>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="bits-book-part1.xml">
<xi:fallback/>
</xi:include>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="bits-book-part2.xml"></xi:include>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="bits-book-part3.xml"></xi:include>
</book-body>
<!-- =============== Back Matter (Ancillary) ======= -->
<book-back>
<ack>...</ack>
...
</book-back>
</book>