6. The method of claim 5 , further comprising: determining whether the OP node satisfies subtree constraints of a tree pattern of the result; if not, then determining that no unique matching is possible and that no candidate match can be derived; and if so, then determining that a tree pattern of the result has a constraint on an order.
6. The method of claim 5 , further comprising: determining whether the OP node satisfies subtree constraints of a tree pattern of the result; if not, then determining that no unique matching is possible and that no candidate match can be derived; and if so, then determining that a tree pattern of the result has a constraint on an order. 7. The method of claim 6 , further comprising: determining whether the order is satisfied by the OP node and its subtrees; if not, then determining that no unique matching is possible and that no candidate match can be derived; and if so, then determining that the result is a full match.