It is an assessment of racehorses which was issued by the International Federation of Horseracing Authorities (IFHA) in August 2007.
These countries are generally in the Southern Hemisphere, although some areas covered, such as Hong Kong and the United Arab Emirates, are actually north of the equator.
The IFHA usually publishes this information when the lower rating represents the overall top performance in a particular category.
They also show the top performers in various subdivisions of each group, which are defined by the distances of races, and the surfaces on which they are run.
The IFHA recognizes five distance categories — Sprint, Mile, Intermediate, Long and Extended — identified by the acronym "SMILE".