Technical notes
QR, RFID and GS1 Digital Link: identifying a single item
The EAN barcode found on almost every product identifies a model: all white size-40 shirts of that article share the same code. To know where one shirt is and what has happened to it, an identifier per individual item is needed. This note compares the possible data carriers and explains how the GS1 standard avoids choosing between an internal code and a universally recognised one.
Identifier, data carrier, syntax
| Identifier | The data that distinguishes the object: an internal code, or a GTIN plus a serial number (in GS1 terms: SGTIN). |
|---|---|
| Data carrier | Where the data is written: linear barcode, QR code, Data Matrix, RFID tag, NFC chip. |
| Syntax | How the data is encoded in the carrier: plain string, URL, GS1 element strings, binary EPC. |
It is best to decide the identifier first and the carrier second: the identifier stays for the whole life of the object, the carrier can be changed or supplemented.
QR code: readable by any phone
A QR printed on an adhesive label or a hang tag costs a few cents, is printed with an ordinary label printer and is read by any smartphone camera. If it contains a URL, reading it opens the object's record directly in the browser.
The limits: line of sight is needed, objects are read one at a time, and counting a thousand garments takes a thousand scans. For a shop with a few hundred items, or a workshop, it is enough to start with.
UHF RFID: reading many objects at once
Passive UHF RFID tags (EPC Gen2 protocol, ISO/IEC 18000-63) are read from a few metres away, without line of sight, at dozens or hundreds per second. A handheld reader passed along a shelf completes a stock count in minutes; a portal at receiving counts a carton without opening it.
They cost more, both tags (in the order of a few tens of cents) and readers, and need care around metal and liquids. In textiles they are now standard for large groups, often with the tag sewn into the care label or inserted in the hang tag.
In the tag the identifier is written in EPC format, typically SGTIN-96: company prefix, item reference and serial number in 96 bits. It is the same data as the QR, in a different syntax.
GS1 Digital Link
GS1 Digital Link is the standard that expresses GS1 identifiers as web URLs:
https://id.example.com/01/08012345678901/21/A7K2M9The 01 segment introduces the GTIN (the EAN padded to 14 digits), 21 the serial number. The same QR therefore:
- opened from a phone, leads to the product page or the item's record;
- read by a compatible till, provides the GTIN like a traditional EAN;
- read by an internal system, identifies the individual object.
With its "Sunrise 2027" programme, GS1 has set the goal of retail tills accepting 2D codes by the end of 2027. It is also the most natural route for the data carrier of the Digital Product Passport.
Combining them in practice
It is not an exclusive choice. An approach that works at different scales:
- start with a short internal code in a QR, as Asset Record does today, to put processes in order;
- where a GTIN exists, the QR becomes a GS1 Digital Link with GTIN and serial, without changing the record;
- where volume justifies it, add an RFID tag carrying the same identifier in EPC format, keeping the QR as a fallback and for the customer.
In all three cases the record and its identifier stay the same; only the carrier used to read it changes.