''You state phase has official definition yet all along you have been arguing for absolute answers in all these threads.
Yes, it does, but that does not prevent us from labeling the three lines in a wye for example as phase A, phase B, and phase C.
When we say phase A for example, we mean the voltage on line A with a unique phase angle which is different from the phase angles of phases B and C. It all goes back to the official definition of phase which is the argument of the sinusoid describing the waves.
I believe in some texts, 'static phase' is defined as opposed to 'instantaneous phase'. That would simply be the phase angle, and that is what we deal with most of the time.