Every elementary data item, every literal, and every function has a class and a category. The class and category of a data item are defined by its picture character string, by the BLANK WHEN ZERO clause, or by its usage; the class and category of a literal are defined in the section Literals.
and the class and category of an intrinsic function are specified by the definition of that intrinsic function (see the topic Intrinsic Functions).
The category of a group item is alphanumeric.
The following table depicts the relationship of categories to classes of data for elementary items.