Used by the routine at ENTER_ROOM.

Called while a room is built (ENTER_ROOM), after the builder. Looks through the 36 places at PLACES for any in use (a graphic) whose current room (+8) is the one he is in, and builds an object record for each in records 2 and 3 (VALVES and VALVE_SECOND) -- the two kept for them: the graphic; U, V and Z from where it is now; the half-sizes 5 by 5 and the height 12; flags $14 (drawn, can be pushed); the room; nothing moving; and at +10 the address of the place, so that the record can be written back (UPDATE_SPECIAL_OBJS). Whatever is left of the two records is cleared.

Knight Lore's find_special_objs_here, instruction for instruction; only the addresses differ. As there, nothing here stops at two: a third place in one room would be built over record 4, the room's first, and the clearing after the loop would then never meet record 4 again and would run on through memory. The 36 places start in 36 different rooms, and a thing is put down only into an empty one of the two records (TAKE_OR_LEAVE), so it does not happen (read; inferred for every way a valve can travel).