Surface Flags
HexMotS/JKPurpose
0x1JKFloor.
0x2JKCog linked.
0x4JKImpassable.
0x8JKAI cannot walk on floor.
0x10JKDouble texture scale.
0x20JK1/2 texture scale.
0x40JK1/8 texture scale.
0x80JKNo falling damage.
0x100JK 
0x200JKHorizon. (Horizon moves as player turns; ceiling does not)
0x400JKCeiling.
0x800JKScrolling.
0x1000JKIcy.
0x2000JKVery icy.
0x4000JKMagsealed.
0x8000JK 
0x10000JKMetal floor.
0x20000JKDeep water.
0x40000JKShallow water.
0x80000JKDirt floor.
0x100000JKVery deep water.