Parse an xml.dom Node object representing a message sending object
        into this object.

def parse_xml_node(self, node):
        '''Parse an xml.dom Node object representing a message sending object
        into this object.

        '''
        self._targets = []
        for c in node.getElementsByTagNameNS(RTS_NS, 'targets'):
            if c.getElementsByTagNameNS(RTS_NS, 'WaitTime'):
                new_target = WaitTime()
            elif c.getElementsByTagNameNS(RTS_NS, 'Preceding'):
                new_target = Preceding()
            else:
                new_target = Condition()
            new_target.parse_xml_node(c)
            self._targets.append(new_target)
        return self