Someone who uses nnrss asked for OPML import and export of subscriptions so that he can move his RSS reading into Gnus.
I think I’ve got it working, but there’s a problem: I can’t find the specs documented anywhere. Sure, the OPML format is (minimally) documented, but I don’t know what attributes other people use or look for. So, for now, I spit out text and xmlUrl which seems to be what Radio uses. Oh, but wait. There’s a problem with case-sensitivity among other things. Hurrah! I love standards and “xml”.