def mktns(self):
        """
        Make the schema's target namespace.
        @return: The namespace representation of the schema's
            targetNamespace value.
        @rtype: (prefix, uri)
        """
        tns = [None, self.root.get('targetNamespace')]
        if tns[1] is not None:
            tns[0] = self.root.findPrefix(tns[1])
        return tuple(tns)