Unique Identifier (UI): A character string, number, or sequence of bits assigned to a discrete entity or its associated attribute which serves to uniquely distinguish it from other like and unlike entities. Each unique identifier has only one occurrence within its defined scope of use. (Ref: DOD Directive 8320.03)
Unique identification (UID): A system of establishing globally unique and unambiguous identifiers within the Department of Defense, which serve to distinguish a discrete entity or relationship from other like and unlike entities or relationships. (Ref: MIL-STD-130N Change 1)
Unique item identifier (UII): A globally unique and unambiguous identifier that distinguishes an item from all other like and unlike items. The UII is derived from a UII data set of one or more data elements. (Ref: MIL-STD-130N Change 1)
Item unique identification (IUID): A system of establishing unique item identifiers (UII) within the DoD by assigning a machine-readable character string or number to a discrete item, which serves to distinguish it from other like and unlike items. (Ref: MIL-STD-130N Change 1)
Item: “Item” means a single hardware article or a single unit formed by a grouping of subassemblies, components, or constituent parts. (Ref: DFARS 252.211-7003)