Bis is a Latin prefix or suffix designating the second instance of a thing, thus preceding ter. An example in recent modern usage is the ITU-T modem standard from the late 20th century, V.32bis. Bis can also refer to:
Pachelbel's Canon in D major, a piece of chamber music scored for three violins and basso continuo and originally paired with a gigue in the same key, experienced a tremendous surge in popularity during the 1970s.
One could argue that there should be one major and one relative minor key for each of the 12 equal tempered enharmonic notes, that is for each of. C; Db(/C#); D; Eb(/D#); E; F; F#/Gb; G; Ab(/G#); A; Bb(/A#); B. totalling 24 keys.