You can tag. A lot.

(Originally posted 1 May 2009).

MSFT Tag is a Windows Mobile application that uses the device’s camera to recognize a graphical image or tag for the purposes of obtaining information. You could print one out as a sticker and place it on a landmark to get a link to its site or Wikipedia definition for example. Each tag consists of a 5X10 grid of triangles (although these can also be smaller circles; overlaid over a background image to create a custom tag), each of which can be in one of four colours. This allows a tag to hold thirteen bytes of data. Information received is of four types – URL, Telephone number, Vcard and free text.

Telephone numbers, text and URLs (with a bit of compression) could maybe resolve from the device i.e. the tag itself stores the URL and the device either directly calls the telephone number or jumps to the URL/displays the text. QR codes work in this way. This is disproved however when a device is switched to “Airplane Mode” and tag recognition just does not work. This means that MSFT Tag on the device jumps to a proxy server that resolves the reference (GUID) extracted from the tag into the information already uploaded to the MSFT Tag site. The proxy servers must be pretty impressive as the whole thing works very smoothly.

Thirteen bytes is enough to store a number of 2.02E+31; each one referencing a separate piece of information. This is broadly comparable to the number of grains of sand on all of the beaches of the Earth so MSFT must be expecting a decent take-up of this.

Tags are really useful for URL links that contain filters tied to a geography in the link e.g. you are at a bus stop and there is a tag that shows bus schedules; whether they’re late or not – for that particular stop. Vcards, Telephone numbers and free text are cool rather than essential e.g. you might use a tag embedded into a colleagues’ email sign-off to get their details into Outlook but it’s never going to be a killer application.