private function addPortType($serviceName)
    {
        $this->addToDebug("Adding portType: '$serviceName'");
        // SH don't add to main doc just yet
        // $portTypeTag=$this->addElement("wsdl:portType", $this->definitions);
        $portTypeTag = $this->addElement('wsdl:portType');
        $portTypeTag->setAttribute('name', $serviceName.'PortType');

        //keep a reference
        $this->portTypeTags[$serviceName] = $portTypeTag;
        //and return
        return $portTypeTag;
    }