The help text in 'command.txt' for "Fire an item" appears to be mostly "Throw an item" (e.g. much of it is inaccurate).
Code:
Fire an item (f) or Fire an item (t) You may throw any object carried by your character. Depending on the weight, it may travel across the room or drop down beside you. Only one object from a pile will be thrown at a time. Note that throwing an object will often cause it to break, so be careful! If you throw something at a creature, your chances of hitting it are determined by your pluses to hit, your ability at throwing, and the object's pluses to hit. Once the creature is it, the object may or may not do any damage to it. You've heard rumors that some objects found in the dungeon can do huge amounts of damage when thrown, but you're not sure which objects those are.... Note that flasks of oil will do a fairly large chunk of damage to a monster on impact, supposedly representing fire damage, but it works against fire elementals too - not that it's exactly worth it by that stage of dungeon exploration. If you are wielding a missile launcher compatible with the object you are throwing, then you automatically use the launcher to fire the missile with much higher range, accuracy, and damage, than you would get by just throwing the missile. Fire or Throw requires a direction. Targeting mode (see the next command) can be invoked with "*" at the "Direction?" prompt. This command takes some energy.