int yaz_errno (int id)
Returns error for target (last request). A positive value is returned if the target returned a diagnostic code; a value of zero is returned if no errors occurred (success); negative value is returned for other errors targets didn't indicate the error in question.
Yaz_errno() should be called after network activity for each target - (after yaz_wait() returns) to determine the success or failure of the last operation (e.g. search).