Think I've got the .class file format sussed now. Or at least, I can generated classes which validate and run correctly, so if I haven't got it right, we really should be worrying. The library is still missing a few bits and bobs, but it's complete enough to unblock our work on BioJava.
Real life: Beautiful, sunny day -- you really wouldn't tell it was October. Now why didn't they listen to my plan for wireless Ethernet in the gardens? *sigh*.