No, add a new type. If your SSN is of type "USSocialSecurity" and the canadian system needs "CanadianTaxID" (sorry, I don't know what it is) then the API will n

No, add a new type. If your SSN is of type "USSocialSecurity" and the canadian system needs "CanadianTaxID" (sorry, I don't know what it is) then the API will not accept the wrong thing in the wrong place. "But what if I label it incorrectly and send it along?" Then that's a bug in your code. No amount of my API design can prevent bugs in your code. All my API can do is not help you write bugs in your code. I can't stop you from reading the random number generator and claiming its output is a USSocialSecurity number, but at least I've done my best for a reviewer of your code to be able to look at that and ask you what you're doing calling that a USSocialSecurity.