Error behavior?

[Carl Howells]

Martin Atkins wrote:
> 
> However, since they are messages to a person for debugging they don't
> need to be machine-readable. The machine just needs to see "protocol
> error" and some natural language string. Natural language does present
> the difficulty that the programmer might not understand the language
> that the ID server speaks, but I doubt we can achieve anywhere near the
> right amount of granularity through error response codes without
> building up an entire library of them which need to be handled... and
> they still need to be described in natural language somewhere anyway.

Ok.  I agree with everything you posted.  I suppose that means I'm 
asking for something in the spec that describes precisely what the 
mechanism *is* to return a protocol error message.