Even in tempered music theory, calling a note a sharp or a flat generally depends on the scale.
For eg: Bb major uses:
Bb C D Eb F G A Bb
while A# major uses:
A# B# Cx D# E# Fx Gx A#
(x indicates double-sharp)
Despite all the notes being exactly the same on a tempered instrument.
For eg: Bb major uses: Bb C D Eb F G A Bb while A# major uses: A# B# Cx D# E# Fx Gx A# (x indicates double-sharp) Despite all the notes being exactly the same on a tempered instrument.