If you have a crossbow, you can Load it with a bolt before using it in combat. This makes your first shot much faster, as you only need to aim and fire.
You can recover your missile with Unload, and check if a crossbow is loaded by looking at it.
Some examples:
>load 2.crossbowYou load a bolt into your crossbow.>load (loads the crossbow you're wielding)But your crossbow is already loaded!>look in crossbowIt is loaded with a bolt.>unloadYou recover a bolt from a crossbow.