THE TEXT OF THE ARMY REGULATIONS GOVERNING SHOULDER SLEEVE INSIGNIA

One of the intentions of these orders were to avoid that we see in this First World War era photograph, the use of multiple insignia on the sleeve. The insignia here are the 1st Division and Third Army (Army of Occupation).

ARMY REGULATIONS No. 600-40 WAR DEPARTMENT 31 March 1944 pages 21-22

56. Insignia, shoulder sleeve.-a. Shoulder sleeve insignia are authorized
for wear by personnel of units definitely assigned to one of the following groups:
	(1) GHQ Reserve troops (one for all units assigned to GHQ Reserve).
	(2) Headquarters, Army Ground Forces, and its organizations not as-
		signed to one of the groups listed in this paragraph (one for all units).
	(3) Army Air Forces.
		(a) One for each air force.
		(b) One for all other Army Air Forces personnel.
	(4) Headquarters, Army Service Forces, and its organizations not assigned
		to one of the groups listed in this paragraph (one for all units).
	(5) Armies (one for each army).
	(6) Corps (one for each corps).
	(7) Headquarters, Armored Center, and its organizations not assigned to 
		one of the groups listed in this paragraph
	(8) Divisions (one for each division).
	(9) Base commands
	(10) Defense commands (one for each defense command).
	(11) Service commands (one for each service command).
	(12) Departments (territorial) (one for each department).
	(13) Military District of Washington.
	(14) Antiaircraft artillery command (one for each command).
	(15) Amphibian commands (one for each command).
	(16) Tank Destroyer units (including center, board, replacement center,
		 and battalions) (one for all units).
	(17) Ports of embarkation (one for all ports).
	(18) Students in Army Specialized Training Program (one for all units).
	(19) Replacement and School Command Army Ground Forces.
 b. Shoulder sleeve insignia are not authorized for wear by trainees at replace-
ments training centers.
 c. Shoulder sleeve insignia will be worn on the upper part of the outer half
of the left sleeve of the service coat, overcoat, mackinaw, field jacket, and the
shirt when worn as an outer garment, the top of the insignia to be 1/2 inch below
top of the shoulder seam.
 d. Members of airborne units will wear the airborne tab immediately above 
the shoulder sleeve insignia of the airborne unit.