An empty <xref> does not copy the cross-reference text as the content
Reported by Clement DAVID (@davidcl)
BUG DESCRIPTION:
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When writing help pages, the writer have to duplicate the xref content whereas the Docbook specification explicitly state : "Unlike Link and the other cross-referencing elements, XRef is empty".
HOW TO REPRODUCE THE BUG:
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Remove the xref content on a currently valid help page, it will not produce any text.
To check the current behavior, try the example of http://docbook.org/tdg/en/html/xref.html