MRC:
Characteristics or qualities of an item,not covered in any other requirement,which are considered essential information for one or more functions excluding nsn assignment.SUPP
Supplementary Features:
Ground radio communication, warning an/grc-221, hereinafter referred toas the grc system, enables control of aircraft alert forces effective in a high altitude electromagnetic pulse (hemp) environment. The grc system provides hemp protection of communication terminals, uninterruptible power, environmental control, and klaxons at each base alert facility. The system consists of shielding enclosure s-687/grc-22 (shield room) ; the control, radio set is a line replacement unit.
