This article is quoted from Wired News "Radio ID Tags: Beyond Bar Codes": http://www.wired.com/news/technology/0,1282,52343,00.html
"An emerging technology could usurp the ubiquitous bar code's quarter-century of quiet domination.
"Radio frequency identification (RFID) tags, which consist of silicon chips and an antenna that can transmit data to a wireless receiver, could one day be used to track everything from soda cans to cereal boxes.
"Unlike bar codes, which need to be scanned manually and read individually (you have to actually see a bar code in order to read it), radio ID tags do not require line-of-sight for reading. Within the field of a wireless reading device, it is possible to automatically read hundreds of tags a second.
"RFID systems originated in the 1940s, when the U.S. government used transponders to distinguish friendly aircraft from enemy aircraft. Through the 1970s, the federal government primarily used the systems for projects like tracking livestock and nuclear material.
Radio tags have been used commercially for delivering packages, handling luggage, tracking food in supermarkets and monitoring highway tolls."
Radio tags are mentioned in Over the Edge, book two, but have more significance later in the series when laundry radio tags used to inform laundry robos of clothing ownership and washing instructions are used to track individuals as they move about in the Aquillion. Tags that can be laundered aren't even in the production line yet, they're working on making an inexpensive tag that can be economically applied in commercial use. However, once radio tags become inexpensive and accesible, their applications may become endless. As the author of the Wired News report states, radio tags are likely to become as ubiquitous as bar codes, the previous novelty of commerical engagement.