UNITPOS.DAT

There are 80 records of 14 values of one byte each. 1120 bytes in total.

unitpos[0] - Y position. 255 if unit specifically unused.
unitpos[1] - X position.
unitpos[2] - Z position. (0 is top level).
unitpos[3] -
unitpos[4] -
unitpos[5] -
unitpos[6] - Seems to be the same number for all records, but does vary between saves.
unitpos[7] - Always 0?

unitpos[8] -

BB's notes:

Always seems to be 255 for X-Com controlled (as opposed to owned) units.

This is NOT race specific, but has something to do with whether a unit has been seen or not. I've observed this value changing to 0 as soon as an alien is spotted by a player controlled unit, even if the alien didn't see the other unit approach.

unitpos[9] - Owner flag. Possible values:
0: X-Com
1: Alien
2: Civilian

unitpos[10] - Unit info flags. Bits (from left to right, 87654321):
( 1) 1: 0 = Invisible, 1 = visible.
( 2) 2: 0 = Dead or unconcious, 1 = active.
( 4) 3: 0 = Small unit, 1 = big unit.
( 8) 4: 0 = Left section of unit, 1 = right side of unit.
( 16) 5: 0 = Upper side of unit, 1 = lower side of unit.
( 32) 6: Only seems to flag for certain tank parts. Could be where tank will fire from?
( 64) 7: 0 = Normal, 1 = under mind control.
(128) 8: Unused?

Ignore bits 4 and 5 if bit 3 is unflagged.

unitpos[11] -
unitpos[12] -
unitpos[13] -