The values of the id attribute on referenced content are changed as the elements are pulled
into the new locations. This ensures that the values of the id attribute within the referencing
topic remain unique.
If an element is pulled into a new context along with a cross reference that references the target, both the
values of the id and xref attributes are updated so that they remain valid in
the new location. For example, a referenced topic might include a section as in the following example:
Referenced topic that contains a section and cross reference
<topic id="referenced_topic">
<title>...</title>
<body>
<section id="sect">
<title>Sample section</title>
<p>Figure <xref href="#referenced_topic/fig"/>
contains a code sample that demonstrates ... .</p>
<fig id="fig">
<title>Code sample</title>
<codeblock>....</codeblock>
</fig>
</section>
</body>
</topic>
When the section is referenced using a conref attribute, the value of the id
attribute on the fig element is modified to ensure that it remains unique in the new
context. At the same time, the xref element is also modified so that it remains valid
as a local reference. For example, if the referencing topic has an id set to "new_topic", then
the conrefed element may look like this in the intermediate document section.
Resolved conrefed <xmlelement>section</xmlelement> element after the conref step
<section id="sect">
<title>Sample section</title>
<p>Figure <xref href="#new_topic/d1e25"/> contains a code sample
that demonstrates ... .</p>
<fig id="d1e25">
<title>Code sample</title>
<codeblock>....</codeblock>
</fig>
</section>
In this case, the value of the id attribute on the fig element has
been changed to a generated value of "d1e25". At the same time, the xref element has
been updated to use that new generated ID, so that the cross reference remains valid.