In message , at 06:43:49 on
Wed, 21 Mar 2012, Charles Ellson remarked:
What we haven't yet uncovered is what the equivalent mechanism is for
the under-18's VISA Debit cards which have replaced them.

....

I do have a sneaking suspicion that to some extent it might work by
making kids believe their cards can't go into the red but without any
certain method of enforcing that while the card is used away from any
communication with the bank.

At least one bank *promises* them they can't. That's why we need to
understand the mechanism.
--
Roland Perry