public function orIf($master = null)
    {
        if ($this->logicalOperator == "and") {
            throw new Exception("ValidationLogicCriteria: Cannot declare a logical operator more than once. (Specified orIf() after calling andIf()). Use a nested ValidationLogicCriteriaSet to combine conjunctive and disjuctive logic.");
        }
        if ($master) {
            $this->master = $master;
        }
        $this->logicalOperator = "or";
        return $this;
    }