On Sun, 13 Dec 2009 15:23:41 -0000, Peter Smyth wrote:

2)

Z2-6 Travelcard on Oyster card
Elephant and Castle NR to Kentish Town
OEP set before entry
Mixed Travel Entry charge deducted on entry
balance adjusted on exit to reflect Z1 NR only extension fare (which
will be the same as the Z1 NR only Oyster pay as you go fare)
OEP removed by exit touch

In this case you are touching in outside your zones, so an Entry charge
will be deducted whether you have an OEP or not.

Elephant & Castle is on the Z1/2 boundary, so it's not outside the
zones of the Travelcard.