Digital Link Identifiers: A Plain-Language Primer

What it is

A plain-language primer on GS1 Digital Link. It separates three ideas that are often mixed up (an identification key, an Application Identifier, and the form in which the data is written), shows one worked example in both an element string and a web address, lists the Application Identifiers common in fresh produce, and points to the GS1 document that defines each rule.

Who it is for

Newcomers to 2D barcodes, and marketing and packaging teams who need the vocabulary. No technical background is assumed.

Newcomers to 2D barcodes

Start with What an identifier is and the worked example. Stop there if you only need the vocabulary.

Marketing and packaging teams

Read the section on dates and lot numbers, then Table 1, so you know which data your label can carry and what to ask your label supplier.

What is inside

• Keys, Application Identifiers and element strings, defined separately
• Why a GTIN names a product type and a lot or serial number narrows it
• Dates and the YYMMDD format, and which date IFPA names for PLU stickers
• One worked example in an element string and in a Digital Link address
• Common Application Identifiers for fresh produce (Table 1)
• Where to learn more at GS1, with versions and links

Key takeaways

• GS1 Digital Link writes the GS1 identifiers you already use as a web address. The GTIN stays the primary key.
• A GTIN names a product type. A batch or lot number or a serial number, added after it, narrows the meaning to a batch or a single item.
• Application Identifiers are the short numeric prefixes that say what each piece of data is. Dates are written year, month, day (YYMMDD).
• GS1 owns the standard. This primer explains it and links to GS1's own publications; the GS1 publication governs where the two differ.

Questions

Does a Digital Link replace the GTIN?

No. The GTIN is the primary key in the web address, and it means the same as in the element string, as set out in GS1 Digital Link URI Syntax 1.7.0.

Is every QR Code on a package a GS1 Digital Link?

A QR Code can carry any text. It is a GS1 Digital Link when it holds a web address written to GS1 Digital Link syntax.

Which date should I use, 13, 15 or 17?

Each is a different date: packaging (13), best before (15) and expiration (17). Use the one that matches what you print and what your trading partner asks for. IFPA names the pack date (13) as optional data for PLU stickers.

Do I need my own web server?

The address names a domain, and who runs the service behind it is a separate decision. GS1 publishes a resolver standard for services that redirect scans.

Where do the rules come from?

From GS1. Syntax is in GS1 Digital Link URI Syntax; symbol and data rules are in the GS1 General Specifications.