[Therion] Revisiting Breaking extended elevations on specific stations

[Tarquin Wilton-Jones]

> extend ignore 8 7 11
> extend ignore 6 7 12
> 
> should save the situation. Am I missing something?

This is basically what I also thought; you need to supply three stations
to control it.

I was going to suggest the opposite notation:
extend prefer 8 7 12
meaning "to get to 12, prefer to start from the 8-7 leg".

But either preferring one triplet, or preventing the other, should work.
So I would be just as happy with your suggestion.

Either of these would also solve the "extend stop" problem at the same time.