.tun files and transposition

[filulilu]

I wonder why the transposition steps are dependent on the tuning file intervals. If for example I use a tuning file with all intervals equal to zero, the transposition menu is disabled. On the other hand if I use a tuning file where the consecutive interval values are an octave then selecting one step up in the transposition menu moves the pitch one octave up.
The way around it is to make new tuning files for every transposition I try. Does anyone have a more elegant solution?
I guess this is not so much of a problem when only 12 note per octave tunings are used.
And speaking of tuning files why Repro-1 is not microtunable? Is it for authenticity?