code/game/turfs/open/lava.dm

LAVA_BE_IGNORING	Generic return value of the can_burn_stuff() proc. Does nothing.
LAVA_BE_PROCESSING	Another. Won't burn the target but will make the turf start processing.
LAVA_BE_BURNING	Burns the target and makes the turf process (depending on the return value of do_burn()).

Define Details

Burns the target and makes the turf process (depending on the return value of do_burn()).

Generic return value of the can_burn_stuff() proc. Does nothing.

Another. Won't burn the target but will make the turf start processing.