On Wed, 2 May 2007, MIG wrote:

On May 2, 7:05 pm, James Farrar wrote:
On Wed, 02 May 2007 18:38:56 +0100, Paul Corfield

wrote:

And *as* you are a genius I am sure you'll be able to work out what a
zig zag is ;-)

Zig-zag is three uses (in-out-in or out-in-out or purchase-in-out) in
quick succession, right?

What use would that be to anyone? I mean, what scam would be pulled by
that means?

Alice and Bob buy a ticket and go to a station. Alice uses the ticket to
pass an entry gate, puts the ticket into an exit gate, retrieves it,
passes it over the gateline to Bob, who then uses it to pass through an
entry gate himself.

It's passback, but slightly more subtle. A system which defeated passback
might not defeat zig-zag.

When I go through the barriers at Charing Cross platforms 1 - 4, just
miss my train and have to head for platform 6 for the next one, I've
never understood why the gates won't let me out. What scam is being
prevented by it?

As above. You might have punched out with the ticket, stayed on the
fare-paid side of the gates, given it to one of your filthy lowlife
accomplices, boarded a train, and let the ruffian wander off to use it
again himself.

tom

--
Oh no - I've just turned my arse into a hand grenade!