A Medieval concept by which rhythmic patterns were regulated, chiefly applied to music of the 12th and 13th centuries. There were six modes which served as a basis for much of the Medieval polyphony.ModeOriginal NotationMeaningPoetic SymbolsModern EquivalentMode Ilong-shortMode IIshort-longMode IIIlong-short-shortMode IVshort-short-longMode Vlong-long-longMode VIshort-short-short rhythmic patterns governing the performance of measured sections of Notre Dame organum and, by extension, polyphonic conductus and early motets (late twelfth-thirteenth centuries). All patterns employ triple meter. In the following short-hand descriptions, "Dah" is worth three units, "duh" two units and "dee" is a single unit; while the vertical stroke act like modern-day barlines showing groupings of three beats. These patterns, once invoked, remain in force in that voice until the notation signals a change. Not related to church modes.