This case-insensitive code system http://medcomfhir.dk/ig/terminology/CodeSystem/medcom-acknowledgement-error-codes defines the following codes:

Code	Display
MSG_Receiver_Identifier_UNKNOWN	Receiver identifier unknown
MSG_Receiver_Identifier_MISSING	Receiver identifier missing
MSG_RECEIVER_UNABLE_TO_RECEIVE_MSG_TYPE	Receiver unable to receive this message type
MSG_VALUESET_VALUE_UNKNOWN	The value provided is not in the valueSet
MSG_CodeSystem_VALUE_UNKNOWN	The value provided is not in the CodeSystem
MSG_Element_To_Long	The value of the element is to long
MSG_Datatype_Wrong	The data type is wrong
MSG_Mailbox_Out_Of_Operation	The mailbox is temporary out of operation
MSG_Damaged_durin_transport	The message has been damaged during trasport