Your comment is the only in the entire discussion that mentions "schema". Having an "other" in a schema is a way to ensure you can run n and n+1 versions at the

Your comment is the only in the entire discussion that mentions "schema". Having an "other" in a schema is a way to ensure you can run n and n+1 versions at the same time. It is Data Model design, of which API design a subset. You can only ever avoid having an other if 1) your schema is fixed and 2) if it is total over the universe of values.