Marine corps dating regulations
Intermediate grades rank in the order listed as follows: Rank among officers of the same grade or of equivalent grades is determined by comparing dates of rank. An officer whose date of rank is earlier than the date of rank of another officer of the same or equivalent grade is senior to that officer.
General Order Number 21, Section VI, Headquarters, American Expeditionary Force in France (13 August 1917) authorized square tags. (Quartermaster, Marine Corps), will be habitually worn by all officers and enlisted men, and also by all civilians attached to the American Expeditionary Force.Under regulations prescribed by the Secretary of Defense, which shall apply uniformly among the Army, Navy, Air Force, and Marine Corps, the date of rank of a reserve commissioned officer (other than a warrant officer) of the Army, Navy, Air Force, or Marine Corps who is to be placed on the active-duty list and who has not been on continuous active duty since his original appointment as a reserve commissioned officer in a grade above chief warrant officer, W–5, or who is transferred from an inactive status to an active status and placed on the active-duty list or the reserve active-status list may, effective on the date on which he is placed on the active-duty list or reserve active-status list, be changed by the Secretary concerned to a later date to reflect such officer’s qualifications and experience. The authority to change the date of rank of a reserve officer who is placed on the active-duty list to a later date does not apply in the case of an officer who (A) has served continuously in the Selected Reserve of the Ready Reserve since the officer’s last promotion, or (B) is placed on the active-duty list while on a promotion list as described in section 14317(b) of this title. They serve to identify Marines who fall in battle and secure a suitable burial for them.Identification tags were probably first authorized in Marine Corps Order Number 32 of 6 October 1916.