A reserved
word is a character-string with a predefined meaning in a COBOL
source unit. Reserved words are listed in Reserved words
There are six types of reserved words:
- Keywords
- Optional words
- Figurative constants
- Special character words
- Special object identifiers
- Special registers
- Keywords
- Keywords are reserved words that are required within a given clause,
entry, or statement. Within each format, such words appear in uppercase
on the main path.
- Optional words
- Optional words are reserved words that can be included in the
format of a clause, entry, or statement in order to improve readability.
They have no effect on the execution of the program.
- Figurative constants
- See Figurative constants.
- Special character words
- There are two types of special character words, which are
recognized as special characters only when represented in single-byte
characters:
- Special object identifiers
- COBOL provides two special
object identifiers, SELF and SUPER:
- SELF
-
A special object identifier that you can use in the procedure division
of a method. SELF refers to the object instance used to invoke the
currently executing method. You can specify SELF only in places that
are explicitly listed in the syntax diagrams.
- SUPER
-
A special object identifier that you can use in the procedure division
of a method only as the object identifier in an INVOKE statement.
When used in this way, SUPER refers to the object instance used to
invoke the currently executing method. The resolution of the method
to be invoked ignores any methods declared in the class definition
of the currently executing method and methods defined in any class
derived from that class. Thus, the method invoked is inherited from
an ancestor class.
- Special registers
- See Special registers.