 This is one of the major differences between Chiefs in the Coast Guard and their counterparts in the Army, Marine Corps, and Air Force.Upon obtaining the rank of master chief petty officer, the service member may choose to further his career by becoming a command master chief (CMC).These personnel are considered to be the senior-most enlisted servicemember within their command, and are the special assistant to the commanding officer in all matters pertaining to the health, welfare, job satisfaction, morale, utilization, advancement, and training of the command's enlisted personnel.