RAIN reader–tag communications use the UHF Gen2 radio protocol. The MIT Auto-ID Center pioneered the early work on the UHF Gen2 protocol in 2002, transitioning the effort to EPCglobal, a subsidiary of GS1, in 2004. EPCglobal ratified V1.0.9 of the Gen2 protocol in Dec. 2004, followed by V1.1.0 in Dec. 2005 to fix errata. In May 2008, EPCglobal ratified V1.2.0, a backward-compatible update to V1.1.0 with new optional features and commands for item tagging. Gen2 V1.2.0 is known colloquially as V1.
In Sep. 2007 Walmart, Best Buy, Tesco, Metro, C&A, Target and others formed a JRG (joint requirements group) within EPCglobal to investigate using Gen2 for electronic article surveillance (EAS). This JRG produced an EAS requirements document in Aug. 2008, at which time the retailers created another JRG to develop requirements for consumer privacy, brand protection, and securely altering a tag’s memory contents in the field (collectively Tag Alteration or TA). This TA JRG ratified its requirements in Nov. 2009. In Aug. 2010, the EPCglobal Consumer Electronics Industry Action Group published its Item-level Tagging (ILT) Requirements which included a need for large user memory that could be partitioned into logical regions (i.e. files). EPCglobal then undertook to add the EAS, TA, and ILT capabilities to the Gen2 protocol, ratifying the revised protocol, Gen2 V2.0.0, in Oct. 2013 and V2.0.1 (to fix errata) in Apr. 2015. Gen2 V2.0.1, known colloquially as V2, is a backward-compatible* enhancement to V1 that supports loss prevention (EAS), brand protection, security, files, and consumer privacy.
ISO standardized Gen2 V1.1.0, V1.2.0, and V2.0.1 as ISO/IEC 18000-63, with each new version superseding the prior one. ISO published V2.0.1 as ISO/IEC 18000-63:2015 in Oct. 2015.
The changes between V1 and V2 are solely logical, meaning they affect reader commands, tag replies, data structures and memory usage but do not alter the waveforms a reader or a tag send over the air.