THE ADVENTURE SYSTEM (1982):
"Room zero is reserved as a storeroom for objects currently not in any room. The player can not get to room zero by using one of the reserved directions. Actions usually do not permit the player to enter this room. The last room is reserved for some sort of limbo state should the player die. This is where the player is sent with a DEAD command. It may or may not contain exits back to the other rooms."