There are seven types of functions:
Alphanumeric functions are of the class and category alphanumeric. The value returned has an implicit usage of DISPLAY and is in standard data format characters. The number of character positions in the value returned is determined by the function definition.
Numeric functions are of the class and category numeric. The returned value is always considered to have an operational sign and is a numeric intermediate result. For more information, see the IBM Rational Development Studio for i: ILE COBOL Programmer's Guide.
DBCS functions are of the class and category DBCS. The value returned has an implicit usage of DISPLAY-1. The number of character positions in the value returned is determined by the function definition.
National functions are of the class and category NATIONAL. The value returned has an implicit usage of NATIONAL. The number of character positions in the value returned is determined by the function definition.
Date-Time functions are of the class date-time and category date, time, or timestamp. The value returned has an implicit usage of DISPLAY. The number of character positions in the value returned is determined by the function definition.
Boolean functions are of class and category boolean. The value returned has an implicit usage of DISPLAY, and is either a boolean true (B"1") or a boolean false (B"0").
Integer functions are of the class and category numeric. The returned value is always considered to have an operational sign and is an integer intermediate result. The number of digit positions in the value returned is determined by the function definition. For more information, see the IBM Rational Development Studio for i: ILE COBOL Programmer's Guide.