public function addInheritance($inhdata)
    {
        if ($inhdata instanceof Inheritance) {
            $inh = $inhdata;
            $inh->setColumn($this);
            if ($this->inheritanceList === null) {
                $this->inheritanceList = array();
                $this->isEnumeratedClasses = true;
            }
            $this->inheritanceList[] = $inh;

            return $inh;
        } else {
            $inh = new Inheritance();
            $inh->loadFromXML($inhdata);

            return $this->addInheritance($inh);
        }
    }