I'm trying to work out whether it is technically correct to have a "slash" chord where the bass note is not one of the notes in the chord.
I thought the main reason for slash chords is to show which inversion of a chord to play.
However, someone has given me the chord progression B – B/A♯ - Gm7 – B/F♯ which shows a slash chord with an outside note in the base.
You will note that A♯ is not in B major.
But isn't it more correct to call that chord Bmaj7 rather than B/A♯ ?
Is there any valid case of having a "slash" chord where the slash note is not in the actual chord?