In an equal tempered tuning, the ratio between any two pitches is the same under any transposition, by definition. This is not true of any other scale.
This means a pitch signal can't be absolute pitches, because that's non
transposable, and it can't be a scalar degree + fraction, because halfway
between 1 and 3 is not 2.
So, pitch is a signal of triples: @(from, to, at)@.