door_stuff -> setup_doors.
Refer to movable_items elements as an array.
first_byte_of_room_structure is an index into four_byte_structures which is a table of room dimensions.

four_byte_structures -> roomdef_bounds
first_byte_of_room_structure -> roomdef_bounds_index

A roomdef's second byte is a count of additional bounds for room objects. These are copied into byte_81BF[] by setup_room.

byte_81BF -> roomdef_object_bounds