MRC:
Those unusual or unique characteristics or qualities of an item not covered in the other requirements and which are determined to be essential for identification.FEAT
Special Features:
19 slots hold up to 16 matrix switching cards (slots 1-16, left to right as viewed from the front), one back up switch card in slot 17, and two control cards in slots 18 and 19; rear of main chassis consists of 16 slots for interface i/o cards, one slot for a termination card, and two half sized slots for the control i/o cards