a formula that can be either true or false

an expression involving and , or , or not

an expression that takes on the value true or false rather than a numeric value

a sequence of one or more logical operands and logical operators

a set of element-action expressions joined by the Boolean operators OR and AND and NOT

A logical primary alone or a combination of logical primaries and logical operators. A logical expression can have one of two values: true or false.

An expression using the operators for logic, AND, OR, and NOT, written `&&', `||', and `!' in awk. Often called Boolean expressions, after the mathematician who pioneered this kind of mathematical logic.

A statement about a relationship between two or more field values and/or constants, which may be true or false. Logical expressions are used in WHERE clauses in SQL statements and in search criteria in SQL*Forms.

A combination of items, system items, system variables, literals and arithmetic logical operators from which a value of TRUE or FALSE is derived; for example:$RECNO LE $NUM1 HRS-WRKD * HRLY-WAGE GE 600 AND $MONTH EQ 5 $NUM1 LE 100

An integer or logical constant, variable, function value, or another constant expression, joined by a relational or logical operator. The logical expression is evaluated to a value of either true or false. For example, .NOT. 6.5 + (B .GT. D).

An expression consisting of logical operators, relational operators, or both that can be evaluated to a value of either true or false.