Boolean expressions are expressions that return logical values by applying specified operations to designated Boolean primaries.

<Boolean expression>

──┬─<simple Boolean expression>──────┬─────────────────────────────────┤
  ├─<conditional Boolean expression>─┤
  └─<try Boolean expression>─────────┘

<simple Boolean expression>

  ┌◄─ <Boolean operator> ─┐
──┴─<Boolean primary>─────┴────────────────────────────────────────────┤

<Boolean operator>

──┬─ AND ──────────────────┬───────────────────────────────────────────┤
  ├─ OR ───────────────────┤
  ├─ IMP ──────────────────┤
  ├─ EQV ──────────────────┤
  ├─ ! ────────────────────┤
  └─<conditional operator>─┘

<conditional operator>

──┬─ CAND ─┬───────────────────────────────────────────────────────────┤
  └─ COR ──┘

Explanation

Conditional operators are similar to their corresponding standard Boolean operators. However, when a conditional operator is used, the second operand is not evaluated if the value of the first operand is sufficient to determine the value of the expressions. The value returned is either 1 (TRUE) or 0 (FALSE) in the low-order bit of the resulting operand; the remaining 47 bits of the operand are undefined.

The following table illustrates the functions of these conditional operators:

CAND has the same precedence as AND, while COR has the same precedence as OR.

Following are examples of Boolean operators:

B:= R1 NEQ 0 CAND R2/R1 EQL R3; 
B:= R1 GEQ 0 AND R1 LSS SIZE(A) COR R2 NEQ A[R1];

The evaluation of a conditional Boolean expression is described in Conditional Expressions.

<try Boolean expression>

── TRY ─┬─<try limited form>────────┬──────────────────────────────────┤
        └─<try Boolean normal form>─┘

<try Boolean normal form>

                       ┌◄─────────────────────────────┐
──<Boolean expression>─┴─ ELSE ──<Boolean expression>─┴────────────────┤

An explanation of <try Boolean expression> is given in TRY Expression.

Operators in Boolean Expressions

The following table lists the operators that can be used in Boolean expressions, along with their meanings. When two operators are listed on the same line, they are equivalent to each other.