Helmet insignia and basic military map symbols
Helmet insignia used by the 101st Airborne Division
Basic Military Map Symbols
Symbols within a rectangle indicate a military unit, within a triangle an observation post, and within a circle a supply point.
Military Units- Identification
The following symbols placed either in boundary lines or above the rectangle, triangle, or circle inclosing the identifying arm or service symbol indicate the size of military organization:
The letter or number to the left of the symbol indicates the unit designation; that to the right, the designation of the parent unit to which it belongs. Letters or numbers above or below boundary lines designate the units separated by the lines: