Duplicate xml:id for bibliomixed elements when using more than one external bibliographies

[fsteimke]

Happy new year to everyone!

I have a document which uses an automatically managed bibliography with two external bibliographies. I detected a duplicate @id in the generated HTML. Both entries with the same @id don't have an bibliomixed/@xml:id in the DocBook source.

I think the issue is caused when an @xml:id is generated for bibliomixed. I think it is guaranteed to be unique for the containing external bibliography, but not when entries from external bibliographies are merged in the DocBook principal input document. If this is correct, then glossentry from more than one external glossary might also be affected.

I was, however, unable to provide a PR for this issue. I tried in the standalone-functions.xsl. I was able to detect duplicate @xml:id values and tried to correct them in mode mp:strip-empty-biblioentries, but without success.

My workaround is: set the @xml:id in the external bibliography.