public function xmlClassAttributeIds()
    {
        if ( $this->xmlClassAttributeIdArray === null )
        {
            // First we want to find all class attributes which are defined. We won't be touching
            // attributes which are in a transient state.
            $xmlTextAttributes = eZContentClassAttribute::fetchList( true, array( 'data_type' => 'ezxmltext',
                                                                                  'version' => 0 ) );
            $this->xmlClassAttributeIdArray = array();

            foreach ( $xmlTextAttributes as $classAttr )
            {
                $this->xmlClassAttributeIdArray[] = $classAttr->attribute( 'id' );
            }
            unset( $xmlTextAttributes );
        }
        return $this->xmlClassAttributeIdArray;
    }