On 17 Sep, 23:31, Charles Ellson  wrote:

> On Wed, 17 Sep 2008 09:09:28 -0700 (PDT), Mizter T
>
>  wrote:
>
> >On 17 Sep, 16:08, Charles Ellson  wrote:
>
> >> On Wed, 17 Sep 2008 00:47:26 -0700 (PDT), Mizter T
>
> >> (snip)
>
> >> >As ever it's difficult to discuss the potential holes in ticketing
> >> >without also flagging them up to those who might wish to take
> >> >advantage.
>
> >> I doubt if that particular fiddle is any secret.
>
> >By its very nature it can't be a secret - as I said in a post
> >upthread, working this through is "hardly beyond the realm of most
> >peoples capacity for logical thought" - however I've never seen or
> >heard or read about it anywhere, and despite my earlier comment most
> >people don't spend a lot of time thinking about such things.
>
> >That said, any fiddle that relies upon this is fairly limited in its
> >scope, and what's more it is unknown whether there are any
> >countermeasures and if so what they are, e.g. if a ticket is pre-
> >encoded for use on a particular day of the week, or on an odd or an
> >even date etc etc.
>
> IMU it would have become encoded (in terms of applying a date) the
> first time it passed through a ticket barrier at an Underground
> station. AFAIAA bus inspectors only have Oyster card readers and Mk1
> eyeballs so presumably a 1-day Travelcard would have to be taken to a
> station unless someone has been specially armed with a magnetic card
> reader.
>

Yes, I understand all that - I was pondering the notion that whilst
these tickets will not be encoded with a specific date, shopkeepers
might be issued with several batches of tickets - each batch being pre-
encoded so as only to be valid according to some criteria, for example
only on Mondays or only on even or odd dates - therefore the
shopkeeper would have to ensure that whatever ticket they sold to the
customer came from the appropriate batch.

Such a 'countermeasure' would mean that there would at least be an
element of uncertainty introduced over whether a ticket gate would
accept a particular ticket (unless of course the fiddler had worked
out how this scheme worked). Of course the advantages of any such
scheme must be offset against the (hardly unlikely) possibility that a
shopkeeper might get muddled up and issue the wrong ticket stock for a
particular day to a customer, which would mean that quite legitimate
passengers could get caught up in the web of suspicion.