Initialised upon entry to a room and then used by the routine at 35090.

There are eight pairs of bytes here that hold the entity specifications for the current room. The first byte in each pair identifies one of the entity definitions at 40960. The meaning of the second byte depends on the entity type: it determines the base sprite index and x-coordinate of a guardian, the y-coordinate of an arrow, or the x-coordinate of the top of a rope.