MRC:
A feature of the item of supply which must be specifically recorded when the reference number covers a range of items.ZZZY
Reference Number Differentiating Characteristics:
An item that supports subsafe critical systems and requires objective quality evidence that quality assurance requirements have been met, including certification of test for hydrostatic and/or operational testing and item ser ialization traceable to the certifications during initial procurement and anysubsequent repairs. Government sources inspection is involved.