On 13 Dec, 13:00, Paul Corfield wrote:
On Sun, 13 Dec 2009 08:57:28 -0000, "Ian F."

[1] I have no idea whether "NR lines" are differentiated for OEP
purposes in the same way that they will be differentiated in terms of
charging rates. Lines currently valid for PAYG stay on the TfL tariff
next year but the lines being added to the system (primarily but not
entirely south of the river) are on the NR tariff.
--
Paul C

The rule will be:
If you are travelling outside the zones of your Travelcard(s) on a
National Rail train, you must load an OEP before boarding that train.

No, you only need an OEP if you are starting within the zones of your
Travelcard and then travelling outside your zones.

correct - starting within zone - travelling beyond zone on NR train