I think you may be referring to the Information-Based Indicia, which is a pre-printed symbol indicated the postage has been paid (among other things). They are included on create-your-own postage stamps (e.g., stamps.com) and are based on the PDF417 standard for two-dimensional barcodes. You can read all about them here: http://www.usps.com/postagesolutions/_pdf/pcibo223.pdf Of course, if this is not what you're asking about, then never mind. :-) Kerry On 8/25/06, Robert Baillie <rjbaillie@frii.com> wrote:

You have probably received mail that has postmarks in the form of a square consisting of pixels, some of which are filled in.

Nearest I can can count, the square is about 42 by 42 = 1764 pixels. If each pixel could be on or off, a lot of data could be encoded there!

Does anybody know what sort of data is encoded there, and how it's stored?

Bob Baillie