As you'll have seen from my signature, I have used film cameras in the past (starting with an Agfa Isola - admittedly not a 35mm format - in 1961) so at least some of the history is known to me, so thanks to all who attempted a constructive critique of my suggestion. I agree that "135 format" is inadequate as an alternative, as someone who used to lust after an XPan should have realised.
The potential K-mount image circle, by the way, is bigger than a 35mm film can handle (it's the mask that limits it to that format, not the mount itself), so that's not a solid argument in favour of sticking with "FF", but, like the rest of you, I'm out of ideas for an easy alternative.
Like many such little issues in life, just naming the beast can be sufficient to dismiss it as a problem, so thanks also to those who, unbidden, provided me with friendly and gratuitous counselling: I must pass some of the more useful phrases on to Dr Phil.