Bit flags are special traits that can be programmed into NPCs to give them certain abilities. Most of these bits are listed in the help_npc.txt file in the user folder, under BitOn, which includes instructions on how to use them for the creation of custom NPCs. The game's own original NPCs already have their bit flags hard-coded, but these can still be modified (via EloSnack or memory editing). Values for ingame bit flag modification are listed under the "Ingame ID" column.