I realize this thread has an official continuation at “Your best musical advice in one post!,” but the new thread really has a different subject and I have a theory question that really doesn't fit in the continuation thread.

Why is the spelling of F#dim7 listed as F# A C Eb? I would have thought it should be F# A C D# because key signatures seem to contain either all sharps or all flats.

Of course a key called F# would have to have six sharps including E# (F) and a key called Gb would have to have six flats including Cb (B). Can there be major keys by those names?

      - Mark