HI Urs,
Thanks for adding some code. I cant see what you mean about making \inc configurable. It just takes the name of an outline. You can run several outlines together at the same time. How could you make this configurable therefore? Let me know what you mean. The usage file shows two list numberings at once.
Please go ahead with the merge. The Gianmaria will be able to use this!
As to validating list style names, that's OK. If anything, I would throw an error and exit. Let them fix it. Then there are no unexpected side effects. I know this goes against the lilypond philosophy of plough on at all costs - but I have never liked that. It always messes up anyway if there is some sort of serious error. I'd prefer the program to stop, and have me fix the matter. But this is only my personal preference. What you have put it fine though. Definitely fliter is more functional style than for-each.
cheerio!
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