Logical expressions

Two or more of these types of operands can be used in combinations, making up two or more expressions within expressions, up to the maximum of five nested levels of parentheses. The result of a logical expression is a '0' or '1' that can be used as part of another expression or saved in logical variables.

The logical operators used to specify the relationship between the operands are *AND and *OR (as reserved values), and & and | (as symbols). The AND operator indicates that both operands (on either side of the operator) have to be a certain value to produce a particular result. The OR operator indicates that one or the other of its operands can determine the result.

The logical operator *NOT (or ) is used to negate logical variables or logical constants. All *NOT operators are evaluated before the *AND or *OR operators are evaluated. All operands that follow *NOT operators are evaluated before the logical relationship between the operands is evaluated.

The following are examples of logical expressions:

((&C *LT 1) *AND (&TIME *GT 1430))
(&C *LT 1 *AND &TIME *GT 1430)
((&C < 1) & (&TIME *GT 1430))
((&C<1)&(&TIME>1430))
 
(&A *OR *NOT &B)
(&TOWN *EQ CHICAGO *AND &ZIP *EQ 60605)

Two examples of logical expressions used in the IF command are:

IF &A CALL PROG1
IF (&A *OR &B) CALL PROG1