... inis nullable. For each nullable link, we createversions of the link, where is the number of nullable strings of that link. There is one version for each of the possible combinations of the nullablestrings ... withstrings in , where . For ,we define, i.e. the set of indexes that ap-pear in .An indexed tuple vector, or ITV, is a vector of tuples of strings over , having the formwhere , and for ,. We write ... ,. The rank of and are, respectively, and. The fan-out of and are, respec-tively, and .The proof of the following theorem is relativelyintuitive and therefore omitted.Theorem 1 For any LCFRS...