Knowledge Base

What is inside the marking code: GTIN, serial number and security data

Marking fields

01GTINTrade item

21Serial numberIndividual unit

93 / 91+92Verification fieldsFormat depends on the category

Verification fields and ECC200 error correction serve different purposes.

Field diagram, not a printable production string.

A full marking code contains several kinds of information. In practical terms it is helpful to separate at least three blocks: GTIN, serial number and security data.

The GTIN identifies the product position. The serial number identifies the individual physical unit.

The security block is used to verify the code inside the marking system. Depending on the format, it may appear as a short 93-based section or as a 91/92 pair.

It is important not to confuse the security block with ECC200. ECC200 belongs to the image-decoding layer, while the security part belongs to the business / verification layer.

When we analyse a damaged code, it matters which of these blocks are already known and which are still unknown.

Sometimes the GTIN is known immediately, sometimes the serial can be inferred, and sometimes the security block is the final missing piece.

Check your damaged markingMarking photo + product barcode with digits, or GTIN.

Check damaged code