Modus (medieval music) "tempus" (corresponding to the modern concept of a measure or bar and referring to the division of "breves" into two or three "semibreves") and "prolatio" (the division of "semibreves" into two or three "minims"). The "modus longarum" was applied primarily to pieces based on a cantus firmus tenor part in long note values. An even longer temporal unit was the "modus maximarum", but it is of little practical importance outside of the 13th century . Modus (medieval music) In medieval music theory, the Latin term modus (meaning "a measure", "standard of measurement", "quantity", "size", "length", or, rendered in English, mode)
Note value duration, as at the end of a piece (e.g. at the end of Mozart's Mass KV 192). A single eighth note, or any faster note, is always stemmed with flags, while two or more are usually beamed in groups. When a stem is present, it can go either up (from the right side of the note head) or down (from the left side), except in the cases of the "longa" or "maxima" which are nearly always written with downward stems. In most cases, the stem goes down if the notehead is on the center line or above, and up otherwise.