set — A collection of books
A Set is a collection of Books. Placing multiple
Books in a Set, as opposed to publishing each
of them separately, has the advantage that ID/IDREF links can then
be used across all books.
Set is the very top of the DocBook structural hierarchy.
There's nothing that contains a Set.
Formatted as a displayed block.
A Set may generate additional front and back
matter (tables of contents and SetIndexs, for example) around
the Books it contains.
Common attributes and common linking attributes.
Specifies an identifying string for presentation purposes
Identifies the editorial or publication status of the element on which it occurs
<set xmlns='http://docbook.org/ns/docbook'>
<title>The Perl Series</title>
<info>
  <author>
    <orgname>O'Reilly & Associates, Inc.</orgname>
  </author>
</info>
<book><title>Learning Perl</title>
<chapter><title>...</title><para>...</para></chapter>
</book>
<book><title>Programming Perl</title>
<chapter><title>...</title><para>...</para></chapter>
</book>
<book><title>Advanced Perl Programming</title>
<chapter><title>...</title><para>...</para></chapter>
</book>
</set>