(1) (GENeration 2) The second version of a product.
(2) The second generation air interface for communication between an RFID reader and tag, administered by GS1 EPCglobal (www.gs1.org). It deals with the modulation scheme, packet structure, command language and methods for dealing with collision. Ratified in 2005, Gen 2 was a major enhancement that standardized on a single data link protocol and included support for worldwide spectrum regulations. It added read/write and tag disable functions, interoperability between devices and the ability for readers to work in close proximity to each other. See RFID and EPC. Classes Tags were given class numbers before Gen 2 was introduced and before the term Gen 1 was coined to refer to the earlier tags and protocols. Although Gen 1 tags are expected to fade into history, there were numerous articles written that mention them. Following is an approximate summary. Tag Gen 1 Type Bits Features Class 0 P 64-96 Read only, Locked* security tag Class 0+ P 64-96 R/W and WORM Class 1 P 64-96 Gen 2 (All classes can be locked) Class 1 P 96-496 Commonly used Class 2 P 96-496 Authentication Class 3 SP 96-496 Integrated sensing Class 4 A 96-496 Ad hoc networking P=passive; SP=semi-passive; A=active RO=read only; R/W=rewritable WORM=write once read many