INTRODUCTION TO NUMBERING SYSTEMS FOR RAIN RFID TAGS

A fundamental question that must be addressed by all users of RAIN RFID technology is, “What should I encode to my tags/labels?”  Stated another way, “Which standard should I use to format the data in my tags/labels?”  This document is intended to serve as an introduction to this topic and to the more detailed information found in the AIM publication:

RAIN RFID tags can be thought of as a blank slate of memory, which can be encoded with data by the user.  This is both an opportunity and a danger.  It is an opportunity in the sense that encodings can be flexible, customizable, and targeted for specific use-cases.  It is a danger however when encodings overlap with each other causing interference between applications and/or are not decodable by reading systems.  The terms “Tag Clutter” and “Tag Pollution” are used interchangeably to denote the problems that arise when tags are not encoded as per a standard (see below for more information).

 

To avoid the pitfalls and allow users to take full advantage of RAIN RFID, tags must be encoded as per a standardized “Numbering System” (aka Encoding Scheme in GS1 terminology).  There are many different standardized Numbering Systems in existence today and more are being developed.  

 

Standardized Numbering Systems fall into two basic categories: 

 

  1. GS1 EPC encodings
  2. ISO-based encodings

 

Each of these categories is further defined by various standards and specific encoding schemes.  The most well-known collection of Numbering Systems is GS1’s Tag Data Standard, release 2.0 of TDS was published in August 2023.  GS1 users work with “Keys,” such as GTIN (Global Trade Item Number, which includes UPC and EAN numbers), SSCC (Serialized Shipping Container Code for logistics units) and GLN (Global Location Number to denote a specific location), which define objects and categories of objects.  The Tag Data Standard defines specific Numbering Systems (again, “Encoding Schemes” in GS1 terminology) that are each based on a corresponding GS1 Key.  For example, the GS1 Key of GTIN can be encoded as any/all of the following Encoding Schemes: 

 

  • SGTIN-96
  • SGTIN-198
  • SGTIN+
  • DSGTIN+

 

GS1 RFID encodings are commonly referred to as Electronic Product Codes, or EPCs. 

 

In contrast, ISO-based Numbering Systems are not defined in a single standards document like Tag Data Standard.  The common approach in the ISO community is to start with a use-case, application or industry-specific guidance and then retrieve the applicable standards, which may be from ISO directly or even from another organization such as IATA for airline baggage tracking or the 6C Coalition for road tolling. 

 

Both GS1 and ISO-based Numbering Systems are generally targeted at specific use-cases / applications / industries and define: 

 

  • Which characters are supported based on specific input character sets (e.g., numbers, alphabetical characters, hexadecimal characters, Asian language characters, etc.);
  • Which character-to-bit conversions are required or supported (often confusingly referred to as “encodings”);
  • Which data elements (e.g., company identifier, product identifier, serial number, date values, etc.) must be encoded;
  • Which data elements may be optionally encoded;
  • Required or allowable sequences of data elements in the encoding;
  • Which tag memory bank(s) are to be used for which purposes;
  • And other more detailed aspects of the encoding.

 

By using either a GS1 or an ISO standardized Numbering System, RAIN implementations can be optimized and multiple problems can be avoided.  The use of a standardized Numbering System: 

 

  • Eliminates Tag Clutter (aka Tag Pollution):  Tag Clutter is when either too many tags are in a read-zone for a reader to process in the allotted time, or when tags from another application are erroneously read.  Eliminating Tag Clutter allows for easy filtering of “my tags” from other stray reads, e.g., quickly filter package level tags from tags on items inside the same package.  
  • Ensures uniqueness: Adherence to a Numbering System prevents different organizations from unknowingly encoding multiple tags with duplicate numbers. 
  • Facilitates resolution: The use of Numbering Systems allows readers to quickly and efficiently resolve tag data to gain additional item information when desired.
  • Supports interoperability: Uniformity of data structures supports supply chain partnerships.
  • Efficiently uses memory space: RAIN RFID tags have limited memory, so data must be encoded efficiently.

 

Given the importance of using a standardized Numbering System with RFID, you must select the appropriate Numbering System for your application.  But which Numbering System should you choose?  If you are already using a standardized Numbering System for your barcode application (or other identification technology), you should continue to use that system.  If you are using your own proprietary “numbering system,” then you must envelop your numbering system in a standardized “wrapper.”  AIM recommends the use of the RAIN Alliance ISO Numbering System as the wrapper for proprietary numbering systems.  

 

If you are not already using a standardized Numbering System and have the freedom to choose, the RAIN RFID Alliance has created a guideline to help you select the best Numbering System for your application.  Simply follow this guideline and the included decision tree, and you will arrive at the most appropriate Numbering System.  Once you have your Numbering System selected, you will need to get into the technical details.  The recommended next step is to consult the relevant section for your Numbering System in AIM’s publication “GUIDANCE ON DATA CONTENT AND STRUCTURE IN PASSIVE RFID TAGS.”  This document will also point you to further documentation that may be necessary to understand the technical details of your Numbering System.