Annotated Source: Zork 1

Set for objects which the player can BURN. (It might be a bad idea, but you can do it.)

This is different from FLAMEBIT, which indicates objects that are currently on fire. See also LIGHTBIT, objects which the player can TURN ON.

Set for objects which are on fire. Such objects normally also have ONBIT.

This is different from BURNBIT, which indicates objects that the player can BURN.

Set for objects which the player can sensibly TURN ON (e.g. the LAMP).

This is different from ONBIT, which indicates objects that are currently lit up. See also BURNBIT, objects which the player can BURN.

Set for rooms in the twisty maze (but not the coal mine maze).

This flag is the basis for the thief’s maze-shuffling taunt.

Set for rooms which are flooded. These can only be traversed with the boat.

Set for glowing objects and naturally-illuminated rooms.

This is different from LIGHTBIT, which indicates objects that the player can TURN ON. See also FLAMEBIT, objects which are on fire.

Set for rooms which are dry land. (Most of them.) The opposite is NONLANDBIT.

Not applied to real objects. RMUNGBIT is a hack used in grammar lines; it means the object is optional (but the preposition before it is required). This allows the parser to accept commands like LOOK AROUND.

Indicates objects the thief will not touch, and rooms where the thief will not go.