The old critter proto spec lists some unknown areas hex offsets 0B-2F, 198-19A, and 19C-19F.
Here's some info about these unknowns:
0C-0F - Light Distance in hexes ( 0-8 )
10-13 - Light Intensity % (0-100)
14-17 - Flags (Flat, NoBlock, MultiHex, etc)
18-1B - Action Flags (Look, Talk)...