Example: Postal codes. Say you're transferring an address in JSON and you have a postal code field. In the UK, postal codes are strings (e.g. "BS42BG"), easy enough. Now, someone enters a US postal code (90505). Should we transfer it as a number, or a string?
OK, that's logical. So where do we specify this without a schema? What happens if a client sends a number instead of a string to the server? Should it accept it and convert it, or return an error?
