In message , at 09:16:21 on Sun, 29 May
2011, Ian F. remarked:
Is there an easy way to do this? I can't find anything on line to help
to work out what the balance would be from, say, boundary zone 3 into
zone 4. Unless I'm missing something which is quite feasible at my time
of life.

My table below may help: eg BZ3 to Southall is "0042 to Southall" at
£1.70 SDS in NFM05

http://www.perry.co.uk/avantix_for_dummies.html

NB. Some routes don't have fares in NFM for this sort of ticket, GWML is
better than MML for example.

--
Roland Perry