S-expressions are irrelevant to my point. S-expressions are just a serialization format; the use of S-expressions does nothing to synchronize semantics between two programs. Labeling a string as a "uri" with an s-expression does nothing to solve the problem I mentioned about mismatched semantics between two programs. In fact, it does nothing to solve (uri "::::::////SUPERINVALID"). Behold the fundamental problem with semantics and why the semantic web has never worked out as its advocates hoped; labeling is the easy part of the problem.