Format 06 vs Format 12 for IUID Marks
Format 06 tags each data element with an ASC MH10.8.2 data identifier; Format 12 uses ATA Spec 2000 text element identifiers. Both produce the same UII. This guide shows the two messages side by side, maps every qualifier, and explains why Format 06 is the default and when Format 12 is called out.
- Updated
- 2026-09-18
- Length
- 972 words
An IUID Data Matrix does not contain the UII as one string. It contains the UII's elements, each preceded by a qualifier that says what the element is, wrapped in an ISO/IEC 15434 message. MIL-STD-130 permits more than one qualifier system, and the message announces which one is in use with a two-digit format code right after the header. The two you will meet on DoD work are Format 06 and Format 12.
The envelope is the same
Every ISO/IEC 15434 message starts with the header [)>, a record separator, and the format code, then carries the data elements separated by group separators, and ends with a record separator and end-of-transmission:
[)> RS <format> GS <element> GS <element> GS <element> RS EOT
RS, GS, and EOT are ASCII 30, 29, and 4. They are non-printing, so on a drawing or in a spreadsheet they are usually written as <RS>, <GS>, <EOT> or as ⟨RS⟩ ⟨GS⟩ ⟨EOT⟩. Only the format code and the qualifiers inside the elements differ between 06 and 12.
Format 06: data identifiers
Format 06 uses data identifiers (DIs) from ASC MH10.8.2. A DI is one to three characters, digits followed by a letter, and it sits directly in front of the data with no space:
[)> RS 06 GS 17V1A2B3 GS 1PPN-A1234 GS SX0001 RS EOT
Here 17V marks a CAGE code, 1P an original part number, and S a serial number unique within that part number. A reader that understands ISO/IEC 15434 parses the three elements and derives the UII D1A2B3PN-A1234X0001, adding the issuing agency code D because the enterprise identifier was a CAGE.
Format 06 is the more common of the two and the default for DoD contract IUID labels and nameplates. It has one practical advantage as well: ECC 200 Data Matrix has a dedicated Macro 06 codeword that stands in for the whole [)>RS06GS header and RSEOT trailer. The encoder spends one codeword on the envelope instead of nine characters, so a Format 06 symbol can come out one size smaller than the same data in Format 12. The size calculator and the generator both account for this.
Format 12: text element identifiers
Format 12 uses text element identifiers (TEIs) from ATA Spec 2000, the airline industry's data standard maintained by A4A. A TEI is three letters followed by a space:
[)> RS 12 GS MFR 1A2B3 GS PNO PN-A1234 GS SEQ X0001 RS EOT
MFR is the manufacturer's CAGE, PNO the original part number, and SEQ the serial within that part number. The derived UII is the same D1A2B3PN-A1234X0001.
Format 12 is called out on aerospace programs whose parts already carry Spec 2000 marking, typically airframe and engine hardware, where the same reader and database handle both the IUID mark and the rest of the fleet's part marking. There is no Macro codeword for Format 12, so the header and trailer are encoded character by character.
Qualifier map
| Data element | Format 06 DI | Format 12 TEI |
|---|---|---|
| CAGE code (manufacturer) | 17V | MFR |
| CAGE code, no role implied | 17V | CAG |
| CAGE code of a supplier assigning the UII to an in-service item | 17V | SPL |
| DUNS number | 12V | DUN |
| Original part number | 1P | PNO |
| Lot or batch number | 1T | LTN |
| Serial within part number or lot (Construct 2) | S | SEQ |
| Serial within the enterprise (Construct 1) | 18S (CAGE + serial in one element) or 25S (IAC + CAGE + serial) | SER, or UCN with SPL |
Two rules follow from the table. First, never mix the two systems in one symbol: a message that opens with 06 must contain only DIs, and one that opens with 12 only TEIs. Second, the format does not change the UII. Whichever you choose, the Registry receives the same concatenated string, so switching formats between a first article and production does not create a new identity for the item, though it will require your reader configuration to handle both.
How to choose
- Read the contract and the drawing. If either names a format, that settles it. Primes on Spec 2000 programs will usually say Format 12 or "TEI".
- If nothing is specified, use Format 06. It is what most DoD receiving points, verifiers, and label vendors expect, and it usually produces the smaller symbol.
- Match what the rest of the part carries. If the part already has a Spec 2000 marking and the same reader will scan both, Format 12 keeps one parsing rule on the line.
- Do not change formats mid-program without telling receiving. Both are legal, but a scanner configured to expect one may reject the other.
A third format, Format 05 with GS1 application identifiers, is also permitted by MIL-STD-130 and appears on items that are already GS1-marked for commercial distribution. It follows the same envelope with 05 as the format code and has its own Macro 05 codeword.
What is not affected
The format is about the machine-readable message only. The human-readable information that MIL-STD-130 requires next to the symbol, typically the enterprise identifier, part number, and serial with their data area titles, is the same either way. So are the module size, quiet zone, and verification grading. Those are set by the substrate and the marking process, which is where the MIL-STD-130 marking service starts.
If you want to see both messages for your own data, the IUID generator builds either format from the same CAGE, part number, and serial, shows the envelope with the separators made visible, and reports the derived UII underneath so you can confirm it matches before anything is marked.