Annotated Source: Zork 2

Set for valuable objects, and rooms which are difficult to reach. Picking up the object or entering the room awards you this many points. (And then the property is set to zero, to indicate that you’ve scored it.)

Valuable objects also have the STAGGERED flag, but the game almost never checks this.

The VALUE property is also used to check whether the demon (and gnome, etc) approves of an object. The value of VALUE is not important here – just whether the property exists at all. (After all, any treasure you’re holding necessarily has VALUE zero.)

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/OFF (e.g. the LAMP). Objects which have been FLUORESCEd also have this, although only to tell you “You can’t turn that off.”

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 which you float in the air – or might float, at least. If the room has any walkable floor, it will also have RLANDBIT.

This flag is also set for objects which are (temporarily) much larger than you. This happens to anything you’re not holding when you shrink yourself in the Tea Room.

Set for “rooms” which are in the open air. The game does not use this flag for anything, however.

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 solid ground. (Most of them.) The alternative is NONLANDBIT, but several rooms have both.

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.

Not used in Zork 2.

Set for valuable objects – not just the demon’s treasures, but the spheres, the wand, and the collar. However, the game generally relies on the VALUE property rather than STAGGERED.