In general, the informal way to define parts of the Triassic period is to use the terms early, middle, and late Triassic. More formally, they are capitalized (Early, Middle, and Late), or sometimes (Lower, Middle, and Upper) and include subdivisions within those groupings. The following lists a general interpretation of the Triassic epochs (although note that many researchers use slightly different notations; for example, many do not list the Rhaetian Age):