An agent application program attempted to return a CMIP error and CMIP services flagged the response as illegal because the error code specified in the response was checked for by CMIP services when the indication was processed and was verified at that time not to have occurred. For example, all object classes are looked up and found in the metadata before the indication is delivered, so the NoSuchObjectClass error cannot occur subsequently. If an application program attempts to return NoSuchObjectClass, CMIP services rejects the response with this error code. The other errors which fall into this category are SyncNotSupported and InvalidScope. CMIP services returns an ROER to all indications that specify a sych other than bestEffort and client agent application program s will never receive an indication that specifies atomic synchronization. Also all scopes are validated to be completely syntactically correct before the indication is delivered to the agent application. So these errors are not allowed by CMIP services. If an agent application program generates these errors, then the agent application program is in error.