Nenano

Phthora Nenano (gr. φθορά νενανῶ, also νενανὼ) is the name of one of the two "extra" modes in the Byzantine Octoechos—an eight mode system, which was created by a reform of the Monastery Agios Sabas, near Jerusalem, during the seventh century. Today the system of eight diatonic modes and two phthorai ("destroyers") is regarded as the modal system of Byzantine chant, and during the eighth century it became also model for the Latin tonaries—introductions into a proper diatonic eight mode system and its psalmody, created by Frankish cantores during the Carolinigian reform. While φθορά νενανῶ was often called "chromatic", the second phthora was named "nana" (gr. φθορά νανὰ) and called "enharmonic", the names were simply taken from the syllables used for the intonation (enechema). The two phthorai were regarded as two proper modes, but also used as modulation or alteration signs. Within the diatonic modes of the octoechos they cause a change into another (chromatic or enharmonic) genus (metavoli kata genon).