QC

QC means"Definition" is not in the list (ability, ambush, armor, berserk, beseech, bestiary, book, command, concept, definition, ...) of allowed values for the "Page type is" property. Quality Control, which is the step in game development when an improvement is passed on to a set of GMs to double check the code and examine it's interactions other systems. This is usually the last step before a system gets released.