CRU: Crust leather, hand stained
VNA: Aniline calf. Feels a lot like Annonay, but I couldn't say for sure
INC: Grain leather (Inca). Rather strong, and stretches nicely over the toe to allow for a nice spitshine.
SHR: Hand stained crust grain leather (shrunken)
RUS: Russian calf/hatch grain
REV: Bovine leather. Waxed. Possible to have both reverse or grain side up.
BUF: embossed calf. Supple and nice.
KUD: softest suede from Saint Crispin's. Long nap.
JAN: Reverse hunting. Soft suede with long nap and a very thick and sturdy feel. My personal favourite.
BCK: calf split suede, short nap
HRS: Chamois deer
JAN CM: Janus calf marraca, reverse hunting.
There are other codes too (FUN, probably more), but I don't have any experience with them.
There's also some scotch grain types still around, but don't have any swatches.
Thanks for these descriptions and detail. Curious, what makes JAN your favorite? Qualities?