[ceejayoz]

So... if the API I use switches from Apache to nginx, I have to rewrite all my success/error handling?

[galaxyLogic]

Of course not, the error-codes should remain the same standard ones as always. I'm saying there are more numbers than those, which could be used for some as yet unidentified purpose.

Perhaps a unique status-code of a server could identify things like the version of content served by it.

[ceejayoz]

That's what ETag headers are for. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ET...