Minkowski spacetime

I think I get some things in the special theory of relativity (STR). And in the Minkowski representation of it. I think I get that there is no two-term earlier-than relation: 'X is earlier than Y' is just not well-formed in the theory. It only makes sense to suppose X is earlier than Y in frame of reference F. The Minkowski representation of STR purports to replace spatial and temporal relations with a more basic spacetime relation. My question: suppose we take two 'events', E1 and E2, in the Minkowski representation each occupying just one point. Is the question what is the spacetime distance between E1 and E2 well formed? Is there a basic spacetime distance relation that is either frame invariant or frame independent in the Minkowski representation?