Tag Data Translation

Tag Data Translation (TDT)

EPC format conversion specification." data-category="Data & Encoding">Tag Data Translation is a GS1 specification that defines the rules for converting between different representations of an EPC identifier. An EPC can exist in three forms — binary (as stored on the tag), tag URI (a canonical text format), and pure identity URI (a human-readable format). TDT provides the deterministic mapping between all three, ensuring interoperability across the RFID ecosystem.

The Three Representations

Consider an SGTIN-96 encoded on a tag:

The binary form is what the tag stores and the reader reads. The tag URI includes encoding-specific metadata (filter value, partition). The pure identity URI strips encoding details, leaving only the business identifier. TDT defines how to convert between any pair of these forms.

Why TDT Matters

Without TDT, every RFID application would need its own bit-parsing logic, leading to inconsistencies and errors. TDT provides:

Interoperability: Different systems can exchange EPC data in any representation and reliably convert to the form they need. A reader reports binary, middleware converts to tag URI for logging, and an EPCIS repository stores the pure identity URI.

Validation: TDT includes rules for validating that a binary EPC is well-formed — correct header, valid partition, GS1 Company Prefix within registered ranges. This catches encoding errors at the point of commissioning before tagged items enter the supply chain.

Scheme discovery: Given a binary EPC, TDT identifies the encoding scheme (SGTIN, SSCC, GRAI, etc.) from the header byte and applies the correct parsing rules automatically.

Implementation

GS1 publishes the TDT specification as a set of XML definition files that software libraries consume. Open-source implementations exist for Java, Python, and JavaScript. Most RFID middleware platforms include TDT as a built-in module.

In a typical integration, the reader reports a hex EPC string (e.g., from an LLRP RO_ACCESS_REPORT). The middleware passes it through the TDT library, which returns the parsed fields (Company Prefix, Item Reference, Serial Number) and the corresponding GS1 key (GTIN + serial). The application then uses the GTIN for product lookup and the full SGTIN URI for EPCIS event generation.

TDT and Digital Link

GS1 Digital Link extends the identifier ecosystem to the web. TDT can convert an EPC pure identity URI to a Digital Link URL (e.g., https://id.gs1.org/01/00614141107346/21/12345), bridging RFID-encoded data with web-based product information. This convergence is increasingly important as Digital Product Passport regulations require consumer-accessible product data.