Commanding Officer

From AWRPedia

A Commanding Officer, shortened to CO, is an army officer that possesses special powers, called CO powers which allow them to lead an army more efficiently. As these powers, the origin of which is unknown, tend to be uncommon even unprofessional men and women can and will be hired by the army.

The important difference between COs in the RP and Non-Player Character (NPCs) is that a CO is obligatory and conisdered the 'main' character of an RPer while NPCs are entirely optional.