"Brian Morrison" wrote in message
...
Jules wrote:


The data's unique within RM's system; there's nothing stopping the user
from making multiple copies, but the data still only permits a single
*valid* entity.



Thus forcing RM to have a constantly increasing database unless they
have other means of limiting validity.

I can't see this today plus one day approach being much use for anything
other than occasional use.

I doubt that the RM have a list of invalid stamps they test against, much
more lightly that the hold a list of valid stamps which age out or are
canceled by the letter arriving at the sorting office.

Anything else would be madness