Complete Encyclopaedia of Music/A/Attendant keys

Attendant keys. According to Boyce and Callcott, attendant keys are the keys on the fifth above and fifth below (or fourth above) any given key, which in modulation are introduced by the addition of a new flat or sharp to the signature. Mr. Maxwell, in his essay on tune, proposes a system of eighteen notes on the octave, which shall make the keys of C major and A minor, with the attendant keys, or six auxiliary scales, perfect, in their harmony, throughout.