def match(self, root, ns):
        """
        Match by I{targetNamespace} excluding those that
        are equal to the specified namespace to prevent
        adding an import to itself.
        @param root: A schema root.
        @type root: L{Element}
        """
        tns = root.get('targetNamespace')
        if len(self.tns):
            matched = ( tns in self.tns )
        else:
            matched = 1
        itself = ( ns == tns )
        return ( matched and not itself )