Initialised by the routine at 87CA, checked by the routines at 8B07, 8FBC and 95C8, updated by the routines at 90B6, 91BE and 94B0, and checked and updated by the routines at 8DD3, 8ED4 and 94D2. Possible values are:

Value	Meaning
0x00	Willy is neither falling nor jumping
0x01	Willy is jumping
0x02-0x0B	Willy is falling, and can land safely
0x0C-0x0F	Willy is falling, and has fallen too far to land safely
0xFF	Willy has collided with a nasty, an arrow, a guardian, or Maria (see 90B6)