A temperament (http://www.ixpres.com/interval/dict/temp.htm) which

maps rational intonation of a given rank in a consistent way to an intonation of smaller rank. A regular temperament is equal, linear, or planar depending on whether the rank, meaning the number of generators, is one, two, or three. In general a regular temperament is described as being of dimension d when it has d+1 generators, and so is of rank d+1.

Mathematically, a regular temperament is an epimorphism (a homomprhism

(<http://mathworld.wolfram.com/GroupHomomorphism.html> which is onto

http://mathworld.wolfram.com/Onto.html) of a rational note group onto a note group of smaller rank. Regular temperaments may be classified according to their wedge invariant, or wedgie.