Service Charlies
commonly referred to as "Chucks"
ENLISTED GRADE INSIGNIA: 4 inches below shoulder seam, centered on the seam. (3 inches below for E8 and above)
OFFICER GRADE INSIGNIA:
BELT: Belts for all uniforms will be worn at the natural waistline with the right edge of the buckle (wearer's right) on line with the edge of the fly or coat front.
Shirt stays: These are the ones to get - with the loops over the foot. Don't get the clips on both sides, they will unclip at the most inopportune time.
From the Order:
The short-sleeve khaki shirt with appropriate service trousers or skirt/slacks is designated as the service "C" uniform. During the winter season, commanders may, at their discretion when the weather requires, authorize the service "C" uniform. This uniform may be worn as a uniform of the day and for leave or liberty, unless otherwise prescribed by the commander, and may be prescribed for formations at parades or ceremonies on and off the military activity. This uniform will not be worn for formal or semiformal social events.
Officer and enlisted female service uniforms are the same, except officers wear their rank insignia on the shirt collar and enlisted Marines wear cloth insignia on their sleeves.