The verify(expr1, expr2, list) and verify(expr1, expr2, list(ver)) calling sequences return true if it can be determined that the two lists satisfy a relation operandwise, either by testing with equality or using the verification .

If true is returned, then each of the pairs of operands satisfied the relation. If false is returned, then at least one pair of operands did not satisfy the relation (a result of type verify(false)). Otherwise, FAIL is returned, indicating that for at least one pair of operands it could not be determined whether or not they satisfied the relation (a result of type verify(FAIL)).

The verification list is symmetric and a verification list(ver) is symmetric if and only if the verification ver is symmetric.

If either expr1 or expr2 is not of type list, then false is returned.