Proc is a common term used in programming to refer to an event triggered under particular circumstances. For example, in WoW, a particular weapon (that hits many times) might have a 10% chance on each hit to apply a special effect, such as poison damage. When WoW users talk about "how often this weapon procs", they are talking about the likelihood of the special effect being processed.
Proc is otherwise sometimes short for "spec_proc" (spec_proc is short for "special procedure") which is a term used by the original programmer of Circle-MUD, Jeremy Elson. It might have been used as well by the original programmers of diku-MUD as well. Special procedures in Circle-MUD are functions that can be assigned to objects, players, and locations in the world such that each time an event occurs, the special procedure function will be invoked. Special procedures were used in Circle-MUD for a wide variety of purposes: Creating room events when a person typed a specific string of text, causing a weapon or piece of armor to perform a magical action, and even causing a MOB (mobile) to do something that it wouldn't normally do.[citation needed] (This may well be the origin of the term.)
Special procedures were a way of creating unique experiences that could not be achieved by simply building the dungeon and populating it with monsters. Special procedures breathed life into these worlds by introducing extra coding that enhanced the gamer's experience without changing the underlying structure or function of the code-base. If you ever played a MUD and were walking around in a dungeon and randomly saw the text "You feel as though you are being watched," that was probably a special procedure.[citation needed]
When developers and players were talking about these special procedures they abbreviated the term to "proc". Over time the noun also became a verb, "proced" ("proc'd" or "procced"), which meant that the special procedure was invoked and performed its action. Most often, players were concerned about their weapons and whether or not the weapon would perform its special attack (a proc), and so proc must have started to take on a narrower meaning for MMORPG players who were somewhat more removed from the core combat engine and flat world of MUDs.[citation needed]
Because this meaning of proc is based on user commands or actions (but always triggered by something the user purposefully does, even though he might not know it) and not on chance, it is different than random procs, such as special random enchantments in WoW like Mongoose.
