Index 13 of DEPTH_ORDER: the boxes overlap on all three axes, and order does not come into it. As in Knight Lore, this is where a valve that shares its space with something else is destroyed. Unless either is out of the collision tests (bit 1 of the flags), a loose valve -- graphics 96 to 99 -- is turned into graphic 64, whose update (SPARKLE_STEP) steps it to 65, whose update (SPARKLE_END_PLACE) empties its place in PLACES and then the record: the valve is gone for the rest of the game. The candidate is checked first; only one of the pair is changed. Knight Lore does this to its collectables (types 96-102); Pentagram does nothing here.

Measured in the simulator: a valve put in the start room where the robot appears, inside his box, was gone -- record and place emptied -- once he had appeared, with this routine's IY branch run; the same valve put above him came to rest on his top.