A worn device is one that is ubiquitous and on the body all the time. Examples include:
- wristwatch (usually just tell time but some have many more capabilities)
- ring (usually just jewelry but some include barcode scanner)
- wallet or purse
- pocket (part of clothing and changed with clothing)
- key chain (usually in pocket, and carried with almost all clothing outside)
- walkman (always with a headset)
- pager (typically with a one-line display, but some up to about 256 char)
- cell phone (often with a headset)
- cordless phone (in some environments supporting PCS or other cordless protocol, the headset is worn on the head or handset on wrist or belt - the base station is fixed in place in the environment and might support base station handoff which allows multiple carriers to cooperate to carry the same signal)
The term mobile device is often used to mean higher-tech worn devices, but there is no real difference in form factor, except that a mobile device is probably more likely to have a display screen capable of displaying more than one line, or an IP number, whereas most of the above don't. It is also more likely to have a bad user interface, contain tantallum, and need to use both your eyes and both hands to make use of. The more Consumerium Services can be deployed without these inconveniences, the more likely they will work.
The Consumerium buying signal will often be received by such a worn device. Although it would ideally be available at the checkout counter or retail shelf or some kiosk in between (inside the retail location), it seems unlikely that this would be available for pilot or early phases, or in hostile retailers who wish to keep selling red-light products without harassment. Accordingly the worn device will have to be supported regardless, and since it serves so many other purposes in the healthy signal infrastructure it seems wise to assume that the healthy buying infrastructure will primarily rely on these devices, and not on any in-store deployment of specialized devices (which probably will be deployed only by those who specialized in green light products anyway, and wish to convince buyers that they are in fact much better than the alternatives not recommended).
See the talk page for a case of doing without a worn device.