>Some time ago, the same question was asked by someone else, and I believe
>my answer and some documentation on the spool format was posted and then
>made available on the Yarn website (www.vex.net/~something???).
Thanks Arnoud, this seems to confirm what I have found by brute force so
far. I've got a bit more, but there are still lots of puzzles.
BTW the actual link is http://www.vex.net/~x/yarnhack.html
Martin