On 14 Dec, 12:19, MIG wrote:
But I am not clear on whether there is a distinction between
"interchange" validators and other standalone validators (ie all along
the DLR) which are neither entry nor exit.

There's a logical distinction between validators that are physically
located between two PAYG routes (eg at Stratford), and validators that
aren't (eg at non-OSI DLR stations), as for the latter it can be
safely assumed you're touching out because you've finished you're
journey. That said, I can't see a pressing need to make this
assumption, so it may be that the latter act exactly like the former.
You'd have to do your experiment to find out.

U