def to_xml_node
el1 = XML::Node.new 'relation'
el1['id'] = self.id.to_s
el1['visible'] = self.visible.to_s
el1['timestamp'] = self.timestamp.xmlschema
def to_xml_node
el1 = XML::Node.new 'relation'
el1['id'] = self.id.to_s
el1['visible'] = self.visible.to_s
el1['timestamp'] = self.timestamp.xmlschema