[docbook-apps] Abstract of set not in navigation when set is nested (DocBook 5.1 using Oxygen 18.0)

[John Tait]

I've found a reproducable error when nesting a set in another set (DocBook
5.1 using Oxygen 18.0). I thought that it might be caused because the set
contained articles (new for DocBook 5.1) but it appears again when the set
contains books. I have reproduced both below.

This affects chunked HTML and EPUB transforms. Both examples are a set (set
A) containing one article/book and another set (set B) containing one
article/book.

After transform, the articles and books appear in the 'Previous'/'Next'
links and EPUB transforms, but the abstract of Set B does not. You can
reach the Set B abstract by the table of contents in the Set A (first chunk
in HTML output) but not by moving through the document.

The two examples are very similar. First example (articles)


<?xml version="1.0" encoding="UTF-8"?>
<?xml-model href="http://docbook.org/xml/5.1/rng/docbookxi.rng";
schematypens="http://relaxng.org/ns/structure/1.0";?>
<?xml-model href="http://docbook.org/xml/5.1/sch/docbook.sch";
type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron";?>
<set xmlns="http://docbook.org/ns/docbook"; xmlns:xi="
http://www.w3.org/2001/XInclude";
    xmlns:xlink="http://www.w3.org/1999/xlink"; version="5.1">
    <info>
        <title>Set A</title>
        <abstract>
            <title>First set</title>
            <para>This is a set of two articles, one of which is in another
set</para>
        </abstract>
    </info>

    <article>
        <title>Here is an article title</title>
        <info>
            <abstract>
                <title>Title of an article abstract</title>
                <para>Text of abstract</para>
            </abstract>
        </info>
        <simplesect>

           <title>Title of simple section</title>
            <para>Text of simple section</para>
        </simplesect>
    </article>


    <set>
        <info>
            <title>Set B containing one article in a set</title>
            <abstract>
                <title>Second set</title>
                <para>Is this text visible?</para>
            </abstract>
        </info>

        <article>
            <title>Here is an article title</title>
            <info>
                <abstract>
                    <title>Title of an article abstract</title>
                    <para>This article is in another set. Did you see the
abstract of set B?</para>
                </abstract>
            </info>
            <simplesect>

                <title>Title of simple section</title>
                <para>Text of simple section</para>
            </simplesect>
        </article>

    </set>

</set>


Second example (books):


<?xml version="1.0" encoding="UTF-8"?>
<?xml-model href="http://docbook.org/xml/5.1/rng/docbookxi.rng";
schematypens="http://relaxng.org/ns/structure/1.0";?>
<?xml-model href="http://docbook.org/xml/5.1/sch/docbook.sch";
type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron";?>
<set xmlns="http://docbook.org/ns/docbook"; xmlns:xi="
http://www.w3.org/2001/XInclude";
    xmlns:xlink="http://www.w3.org/1999/xlink"; version="5.1">
    <info>
        <title>Set A</title>
        <abstract>
            <title>First set</title>
            <para>This is a set of two books, one of which is in another
set</para>
        </abstract>
    </info>
    <book>
        <title>Here is a book title</title>
        <info>
            <abstract>
                <title>Title of an book abstract</title>
                <para>Text of abstract</para>
            </abstract>
        </info>
        <chapter>
            <title>Chapter title</title>
            <simplesect>
                <title>Title of simple section</title>
                <para>Text of simple section</para>
            </simplesect>
        </chapter>
    </book>
    <set>
        <info>
            <title>Set B containing one book in a set</title>
            <abstract>
                <title>Second set</title>
                <para>Is this text visible?</para>
            </abstract>
        </info>
        <book>
            <title>Here is a book title</title>
            <info>
                <abstract>
                    <title>Title of an book abstract</title>
                    <para>Text of abstract. Did you see the abstrract of
set B?</para>
                </abstract>
            </info>
            <chapter>
                <title>Chapter title</title>
                <simplesect>
                    <title>Title of simple section</title>
                    <para>Text of simple section</para>
                </simplesect>
            </chapter>
        </book>

    </set>

</set>