Prolation

A 16th-century manuscript of a Kyrie by Jacques Barbireau, written using mensural notation

In mensural notation, prolation (Latin: prolatio) is used to describe the rhythmic structure of medieval and Renaissance music. The term is used to the division of the semibreve, and corresponds roughly to the concept of time signature in modern music. Time (Latin: tempus) is used in mensural notation to describe larger scale rhythmic structures.

The division of semibreves by three into minims is called prolatio maior; binary division is called prolatio minor. The symbols used to denote the prolation and tempus were Circle with dot, Circle without dot, Semicircle with dot, and Semicircle without dot.