The use of the terms surround UID vary a bit in the defense industry. Here is how we use them.
•UID - Unique Identification, which generally describes the global standards for uniquely identify things.
•IUID - Item Unique Identification is a specific use of UID, used by DOD to identify items of value or critical serialization need. We rarely use IUID, assuming that everything that passes through MIL-Comply is IUID.
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UII - Unique Item Identifier is the actual identifier that uniquely identifies items globally, when used according to IUID standard practices.
•Data Matrix Symbol - is the symbol affixed to items that may be scanned to determine the item's UII. Data Matrix refers to the bar code symbology used to print it and which scanners must be compatible with to read it.
•Part Mark - refers to the Data Matrix UID symbol affixed to an item, as opposed to the PDF417 symbol on its container label.
•PDF417 - while similar in appearance to Data Matrix, PDF417 symbols are used on Mil-Std-129 container labels rather than items.
•Machine-Readable Interface (MRI) refers the standard-driven data structures found in Data Matrix and PDF417 symbols that allow scanners to understand their data.
•Mil-Std-129 is the military standard which specifies container labeling
•Mil-Std-130 is the military standard which controls marking of property, as opposed to .
The term UID can be used in a general sense, referring to all aspects of Item Unique Identification (IUID) as implemented by the DOD, including the part mark, the UII and the data that accompanies it. The UII (Unique Item Identifier) is the most elemental UID component consisting simply of a string of up to fifty characters, such as D1HLD9WIDGET-99000001. Without context nothing about the UII can be positively discerned but the entity responsible for its creation.
UIIs start with an Issuing Agency Code (IAC) which indicates the type of Entity identifier that follows it. Most defense UIIs are issued under CAGE codes, thus start with a ‘D’ indicating that. In the example above we can determine that the UII was issued by CAGE code 1HLD9, but little else. UIIs are also known as Concatenated UIIs, because they are a concatenation of an IAC, CAGE code, an optional part number, and a serial number.
When a UII is submitted to WAWF or listed in the PDF417 symbol of a Mil-Std-129 container label it is accompanied by additional information such as construct, serial number, and noun/nomenclature. This is referred to as a UID, by MIL-Comply software and documentation. A UID record includes the UII and these other components, as well as the contract, order, shipment and CLIN under which the UID-marked item was, or will be, supplied to the Government.
Supply-chain compliance systems like MIL-Comply use a number of heuristics to determine the components of UIIs based on the context under which they are collected. This is made easier when the UID marking on an item can be scanned, because the two-dimensional Data Matrix symbol includes data separators and identifiers of its components. This leaves only a determination of the nomenclature, which can be done by looking up the part number in a database or querying the user. The 2D UID symbol is referred to as a Data Matrix or Machine-Readable Interface (MRI) to indicate that its components are readily available.