Reserved words
A reserved word
is a character-string with a predefined meaning in a COBOL source unit. Reserved
words are listed in Appendix E. 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, used in a
method procedure division:
-
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.
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