For anyone interested in the STOS file structure, I've added it to the wiki: STOS.BAS wiki entry
Still not figured out memory banks, and what I've posted could well be wrong or incomplete, please let me know if so!
I've provided the token lookup tables too, for the base STOS instructions, and also for the Misty 1.7 extension. If anyone can add to this list with more extensions, please do. I'll try and add more of my extensions soon.
This work was done as part of my (PC based) STOS editor, which amongst other benefits, will provide a much easier way of sharing STOS source code - previously (if I'm not mistaken) to share STOS source code you had to have the same extension configuration as the writer of the code, somewhat impossible if you didnt know the author.
Anyway - I hope someone finds this useful!