A longa (pl. longe or longae) or long is a musical note that could be either twice or three times as long as a breve (Am.: double whole note, or double note), four or six times as long as a semibreve (Am.: whole note), that appears in early music. The number of breves in a long was determined by the "modus" or "mode" of a passage. Sections in perfect mode used three breves to the long while sections in imperfect mode used two breves to the long. Imperfect longs, worth two breves, existed in perfect mode from the earliest sources (late 12th century), while the fourteenth century saw the introduction of perfect longs, worth three breves, in imperfect mode through the use of dots of addition (puncti additiones).