Twitter uses an Error Code message system with their API: https://dev.twitter.com/overview/api/response-codes Look under "Error Codes."
I am wondering what HTTP Status code they use for ones that do not correspond to an HTTP status code, for example 231 "User must verify login"
Does anyone know? I am modeling a similar system and am using them as a model.
Alternately, what would be the best approach, I thinking maybe 422 for unprocessable entity for one's that do not correspond since it's fairly generic, but am open to suggestions on this.