since x and y are simple names, have simple values, and are unique pairs that apply only once to a point: attributes. to use anything else means relying on an

since x and y are simple names, have simple values, and are unique pairs that apply only once to a point: attributes. to use anything else means relying on an arbitrarily-complex custom schema rather than the much-simpler-and-far-more-standard schema of the language itself. similar to how we use datatypes in programming languages rather than just strings everywhere. both work! one is clearly giving up a lot, and gaining little.