Names

A name used to denote part of a statement such as a verb, option, or clause, is called a keyword. All statements, except the assignment statement, begin with a keyword that identifies the purpose of the statement.

A name can also denote an object operated upon by the program, such as a variable, file, or label. These names are known as identifiers. Their meanings are established by a declaration.

In this example, G and Y are identifiers. READ, FILE, and INTO are keywords.

READ FILE (G) INTO (Y) ;

There are no reserved words in Open PL/I. In this example, TO names a storage location.

GOTO L;
CALL S(B,C,D);
RETURN; 
STOP;
DO K = 1 TO 11;
TO = 20; /* ASSIGNMENT STATEMENT*/

The following example shows how names can either establish an object to be operated on or denote part of a statement.

DECLARE X(5) FIXED; 
L: X(3) = 25;

Both X and L are identifiers, but DECLARE and FIXED are keywords. X is declared by a DECLARE statement; L is implicitly declared as a label.

A name consists of any combination of the following:

• letters
• digits
• _ (underscore character)
• @ (at sign character)
• # (pound sign character)
• $ (dollar sign character)
• a sequence of any of the above characters

The following rules apply to names.

• Any of the alphanumeric characters A through Z, a through z, and 0 through 9 can be used.
• A name must not contain more than 32 characters.
• Names cannot contain blanks or hyphens.

Examples:

STREET_NAME
@BETA
#Y7
C
$7

Names can be written using both uppercase and lowercase letters.

By default, all lowercase letters are interpreted as their uppercase equivalents. The -lowercase compiler option causes the reverse of this behavior. Refer to the Open PL/I User's Guide for more information on this option.

Because there are no reserved names in Open PL/I. Names that are used as keywords, 1such as READ or INTO, can also be identifiers. However, this practice makes programs difficult to read and should be avoided whenever possible.