Postgresql XML parsing

Hi,

I am working on adding a functionality to PostgreSQL. I need to parse
the XML format query plan (produced by PostgreSQL v9.3) and save it in a
simple data structure (say C structure). I was wondering if PostgreSQL
already had any parsing functions implemented that I can use to do the XML
parsing. This is getting difficult as I was not able to get any DTD or XML
Schema for the XML files generated by PostgreSQL.

I found the files xpath.c/xslt_proc.c files that contain parsing related
code, but none of the functions are being called for any xml related query
I issue to the database and some of the functions in those files mention as
deprecated.

It would be greatly helpful if someone could guide me on this.

Thank you.

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Regards,
Ashoke