The collation sequence definition shall be used by regular expressions, pattern matching, and sorting. A common method for adding characters to an alphabet is to use diacritical marks. In some languages, this creates a completely new character, collated differently from the Latin base. This concept is most applicable only if the number of weight levels is two. In general, the characters in the same equivalence class will have secondary collation values that vary.
Collation order is expressed in terms of collation values.
This does not imply that implementations shall assign such values, but that ordering of strings using the resultant collation definition in the locale shall behave as if such assignment is done and used in the collation process. These functions were obsolescent in AIX 3.2, and may no longer be supported. Equivalence classes are supported. Supports forward and backward searches at different weight levels. Backward and forward ordering is a requirement defined in the Canadian and other proposed standards for collation.