Came across the line "Mutta kuka muistaa Ursulaa, hän täysin unohtui . . . " and thought that "unohtui" must be some past participle of "unohtaa" but I couldn't figure it out.
Next stop, Fintwol, the Finnish Morphological Analyzer, where it tells me that "unohtui" is the DV-U V PAST ACT SG3 not of "unohtaa" as I'd imagined, but of "unohtua," which is a brand new verb to me, and which my dictionary tells me means "to be forgotten." Oh dear. Poor Ursula

Now, usually, I'm pretty good at doping out the Fintwol parts of speech abbreviations, but the DV-U has me stumped. I assume the V is for verb, but the D and the U? Any ideas? Any examples from other verbs? I thought that maybe this is the same form as as "tehdä - tehty," but not so, according to Fintwol.
Also assume that PAST ACT SG3 means that it a past tense, active voice (i.e.: not passive) and third person singular? Not sure about that, though.
If I recall correctly, there used to a legend on the Morphological Analyzer site that provided a key to the abbreviations but I don't see it any more. It also occurs to me that it would be a real disaster if this handy-dandy site were to disappear from the web. Is there anything else like it out there?