Editing Time signature (section)

===Mensural time signatures===
{{Main|Mensural notation#Mensurations}}
In the [[mensural notation]] of the 14th, 15th and 16th centuries there are no [[bar (music)|bar]] lines, and the four basic ''mensuration signs'' [[Image:Mensural time signature 1 (alternative).svg|x13px]], [[Image:Mensural time signature 2 (alternative).svg|x13px]], [[Image:Mensural time signature 3 (alternative).svg|x13px]], [[Image:Mensural time signature 4 (alternative).svg|x13px]] indicate the normal ratio of [[duration (music)|duration]] between different [[note value]]s.  Unlike modern notation, the subdivisions could be either 2:1 or 3:1. The relation between the ''[[Breve (music)|breve]]'' [[File:White mensural brevis.svg|x20px]] and the ''[[semibreve]]'' [[File:White mensural semibrevis.svg|x20px]] was called '''tempus''', and could be perfect ([[meter (music)#Triple meter|triple]] 3:1 indicated by circle) or imperfect ([[meter (music)#Duple meter|duple]] 2:1, with broken circle), while the relation between the ''semibreve'' and the ''[[minim (music)|minim]]'' [[File:White mensural minim.svg|x20px]] was called '''prolatio''' and could be major (3:1 or [[meter (music)#Compound meter|compound]], indicated by dot) or minor (2:1 or [[meter (music)#Simple meter|simple meter]]).

Modern transcriptions often reduce note values 4:1, such that
* [[Image:Mensural time signature 1 (alternative).svg|13px]] corresponds to {{music|time|9|8}} meter;
* [[Image:Mensural time signature 2 (alternative).svg|13px]] corresponds to {{music|time|3|4}} meter;
* [[Image:Mensural time signature 3 (alternative).svg|12px]] corresponds to {{music|time|6|8}} meter;
* [[Image:Mensural time signature 4 (alternative).svg|12px]] corresponds to {{music|time|2|4}} meter.

In mensural notation actual note values depend not only on the prevailing mensuration, but on rules for [[Mensural notation#imperfection and alteration|imperfection and alteration]], with ambiguous cases using a dot of separation, similar in appearance but not always in effect to the modern [[Dotted note|dot of augmentation]].