Right, now I get it.
(c) one of the tickets is a Season Ticket (which for this purpose does not include Season Tickets or travel passes issued on behalf of a passenger transport executive or local authority) or a leisure travel pass, and the other ticket(s) is/are not.
The clue is in the "(s) is/are". My reading of the NRCC 19c always understood it to be One Season + One Non-Season. I have checked the wording, and you are correct: "(s) is/are". Has this recently changed (last two years or so) or have I always looked through it?
Been around quite a while like that, but I've found in the past that it's not been all that well understood even by the train crews (rather uncomfortable incident reported here in the past, but they may be better now).
The intent is that if you have (say) a London to Maidenhead commuting season but you want to go out to Reading to enjoy an evening there, you can catch an express and just pay the extra Maidenhead to Reading fare. The effect of the multiple non-seasons is that you can buy a season for quite a short distance and eliminate the need to make certain stops when splitting. As an example, I can reduce a certain peak day trip into London down from ^157 to ^94.80 and not have to catch certain trains that make certain intermediate stops. That's only a little more expensive that a "conventional split" and much more flexible ... and still totally within the rules.
