These are the names most commonly given to the Principal of 2' pitch in the manuals and 4' pitch in the pedal. The pipes are of open metal construction. Kleinoktav is also a synonym for Twenty-Second. On theatre organs, according to Strony, the Fifteenth is extended not from a Diapason but from a string, usually a Viol d'Orchestre. Authorities differ as to the meaning of Octavin.
Osiris contains over 400 examples of Fifteenth, nearly 400 examples of Super Octave, 275 examples of Doublette, 150 examples of Quincena, 80 example of Supero[c/k]tav, 25 examples of Superoctaaf, 16 examples of Klein[e]o[c/k]tav[e] (of which nine are at 2' pitch), and 15 examples each of Decimaquinte and Quintadecima. Of the nine examples of Sedecima, none are at 2' pitch, and the single example of Fifre is at 1'. No examples are known of Disdiapason, Octava Composita, Quindecima, Quinzième or Regula Minima. Contributions welcome.