Constant-names are user-defined words described in the Data Division in level-78 data description entries. A constant-name may be used wherever a literal appears in a format. Its effect is as if the literal in the VALUE clause of its data description had been written instead. A constant-name with an integer value can also be used wherever a format requires an integer; for example, as a level number or segment number, or in a PICTURE character-string.
A constant-name can only be used after it has been described; that is, it cannot be the object of a forward reference.