In message
, at
02:58:18 on Mon, 25 Jan 2010, MIG
remarked:
I thought I understood Oyster, but those remarks make no sense to
me. If someone is "always touching in and out", how they possibly
be charged more than the daily cap?

In a phrase "unresolved journeys". OSIs can accidentally create them.

Yes; eg you go from Greenwich to Charing Cross (with a change at
London Bridge), take your snaps of Nelson, then go into the
Underground for a trip to Kew Gardens. Because Charing Cross is an
OSI, probably with a long timeout, the whole thing ends up as a single
journey which could go beyond the time limit, leaving you with an
unresolved journey and an unstarted journey at Kew, both of which are
charged at maximum. Once you've got an unresolved journey (I'm pretty
sure) all capping goes out of the window.

That's bonkers! The system has the time I touched back in at Charing
Cross, and can therefore update its expectation of when I could possibly
get to Kew.

On the other hand, if it wants to spot someone getting "too much value
for money", then rather than create two unresolved journeys, it could
split the trip at Charing Cross, and charge two individual journeys.
--
Roland Perry