 were also beginning to be used in passport systems though that proved complicated as well. For consumer and retail applications the problem remained one of cost. Even a few cents matters if it's a can of beans that you are trying to sell. Traditional printed label bar codes, however, are effectively zero cost and have benefited from years of intensive investment in optical scanning techniques. RF ID tags also have competition from other offerings such as long-wave magnetic systems5 operating at wavelengths below 450 kHz. These system options have their own standard (IEEE P1902 Standard for Long Wavelength Wireless Network Protocol) and some application advantages, for example the ability to work underwater and/or underground. As with RF tags, magnetic tags can be active or passive. The active devices have a claimed life of 10 years or more from a (coin-sized) lithium battery. Read rates are typically between 300 and 9600 bits/s. RF ID tags and long-wave magnetic tags both have sufficient address bandwidth to sup- port IPV4 or IPV6 addresses. This suggests a shift in functionality beyond present 'visibility network' or 'visible asset' applications to a broader application base in which wireless inter- rogation of an RFID prompts the interrogating device to access a web page. To place this in the context of our Oyster card and Memory Spot examples, we do not necessarily need to download information from an embedded device other than an IP address that is then used to access information from a supporting web site. In 2006 and 2007 the IEEE coordinated substantial standards work6 on these long- wavelength device systems but five years on ubiquitous applications have failed to emerge. Probably an example of a solution to a problem that didn't really exist. 19.5 Contactless Smart Cards, RF ID, Memory Spot and Mote (Smart Dust) Applications Our third microdevice example, mote-sized smart dust devices, seem very different. These devices are intended to be deployed as self-configuring ad hoc networks that interact with e