The following logical operators logical operators are supported, listed here in their evaluation precedence: NOT Boolean NOT Boolean NOT operation ~ Boolean NOT Boolean NOT operation AND Boolean AND Boolean AND operation OR Boolean OR Boolean OR operation When a complex logical expression has multiple OR conditions, you should group the OR conditions and order them from least complex to most complex to result in the most efficient processing. If the probability of occurrence is known, you should order them from the most likely to occur to the least likely to occur, because once any part of a compound OR condition evaluates to TRUE, the remainder of the expression can be bypassed. However, this is not guaranteed. This is also true of the order of MAP function conditions. Whenever AND and OR logical operations are mixed in the same expression, you should use parentheses to group within the expression to ensure correct evaluation and to clarify the intent of the expression. For example consider the following: isCurrentRevolv := trades.trd_type = 'R' AND trades.trd_rate = '0' OR trades.trd_rate = '1'; does not produce the intended result. Use of parentheses ensures correct evaluation, as shown below: isCurrentRevolv := trades.trd_type = 'R' AND (trades.trd_rate = '0' OR trades.trd_rate = '1'); The following function can be used to perform an XOR operation on 2 Boolean values: BOOLEAN XOR(BOOLEAN cond1, BOOLEAN cond2) := (cond1 OR cond2) AND NOT (cond1 AND cond2);