A monster's item usage property describes which types of items it can use:
- "Open doors" means the monster can open doors but not use inventory-type items.
- "Carried items" (stored in the code as "MONUSE_STARTING_EQUIPMENT") means the monster is sometimes generated with items that it can use. The items a monster starts with is dependent on its type; gnolls tend to start with polearms, for instance; Sigmund always carries a magical scythe and often a wand; deep dwarves may carry potions; centaurs always have bows and may sometimes have barding.
- "Pick up items" ("MONUSE_WEAPONS_ARMOUR") means that not only may the monster start with items, but that it may pick up and use items that are on the floor. Try to keep such monsters away from wands, and especially away from your stash.
Monsters that can carry or pick up items can also open doors.