In message , Paul Corfield
writes
What happened here is that Pre-Pay deducts a value (£1.60 in Z1 and £1
elsewhere IIRC) upon entry. It then works out whether to deduct any more
money at your eventual exit.

Now I'm confused.
I thought that the reader first determined if there was enough Pre Pay
to allow entry. (£1.60 Zone 1 or £1.00 other zones), then deducted the
maximum fare (which obviously might result in a negative balance) which
was refunded on exit if the fare was less or a negative balance if the
fare was more than the Pre Pay on the ticket.
--
Kat Me, Ambivalent? Well, yes and no.