xmpp.xsl file?

Hi,

[Apologies in advance: I am very, very new to DocBook, so the below question might have an obvious answer or might be obviously un-answerable by this list.]

At my new job, I inherited a publishing process that I don't understand completely, and unfortunately the people who set this up have left the company years ago. It looks like we're using a file called xmpp.xsl to customize the default stylesheets (I guess?), but I can't figure out where this file came from (I doubt someone wrote it in-house). Has anyone seen this before?

My company is looking to standardize tools and I'm evaluating oXygen, but they use the namespace-aware stylesheets and I'm trying to understand what our existing stylesheets *do*, so I can then make the needed changes... Right now, I'm failing at this :)

Thanks a lot for any help!

Jen