"The relationship between different notes, now that is another matter. "

I think that is exactly right Richard. There was a time when A was different in different countries I have heard. We only know it is A because some said it was and everyone else paid attention. That A could could have been 441. It is the relation ship between identified tones that we hear as perfect. Any anyone who can hear that relation has perfect pitch.   And the name is assigned to that tone and is recognised by others could be A, B, C or even M, N, O, P.

IMHO

Don