A script is one of possibly several sets that form an exhaustive partition of the type character.
The number of such sets and boundaries between them is implementation-defined. Common Lisp does not require these sets to be types, but an implementation is permitted to define such types as an extension. Since no character from one script can ever be a member of another script, it is generally more useful to speak about character repertoires.
Although the term ``script'' is chosen for definitional compatibility with ISO terminology, no conforming implementation is required to use any particular scripts standardized by ISO or by any other standards organization.
Whether and how the script or scripts used by any given implementation are named is implementation-dependent.