OLC: On-Line-Creation, the ability to create rooms, mobs, objects, shops, and triggers on-line. Desc: Short for description. Flag: A bit-vector that tells the mud that a particular monster, object, or room has a certain quality. (i.e. Dark, Magic, Aggressive) This will be explained more later. Mob: Mobile. A monster. Obj: Object. VNUM: An obj, mob, room, shop, or triggers unique identification number. @ Stands for Virtual Number. Zone: Used synonymously with area. Trigger: Used synonymously with script. PC: Player Character. Not a mob. NPC: Non Player Character. Mobs.