Along with the NOAA Commissioned Officer Corps, the Public Health Service Commissioned Corps is one of two uniformed services that consist only of commissioned officers and has no enlisted or warrant officer ranks, although warrant officers have been authorized for use within the service.[11] Officers of the PHS are classified as noncombatants, unless directed to serve as and part of the armed forces by the President or detailed to a service branch of the armed forces.[12] Members of the commissioned corps wear the same uniforms as the United States Navy, or the United States Coast Guard (when assigned to the Coast Guard), with special PHS Commissioned Corps insignia, and hold ranks equivalent to officers of the U.S. Navy and U.S. Coast Guard.