Since documentation for creating OO-Calc XML export filters is sparse, I better list the following snippet here as well. It’s an export filter for Laurent Rodemerks Vokabeltrainer.
You create a spreadsheet w/ 3 Columns (source language, description/grammar and target language), add the filter, put some info in the first row (see xslt script) and then you’re able to export to the xml format used by the app.
This is far from perfect but does the job and might be the base for further improvements. Since I don’t see a use in diving deeper into the depths of OO xml filters I leave it as is for now.