When creating new 'GEDI Message Codes' or 'GEDI Status Codes', it is recommended from Golden EDI side that you try to use a relevant code from the linked excel document. This is to avoid unecessary missunderstanding when communicating around these codes.
Nevertheless, sometimes you need codes that is not yet defined in the standard and then you can name it whatever you like. If you choose to name your own codes, please try to follow the naming convention as descibed in the excel document.
The excel document has 3 tabs;
MessageCodes - A list of standard 'GEDI Message Codes'.
StatusCodes - A list of standard 'GEDI Status Codes'.
MessageCodeNaming - A description of naming convention for 'GEDI Message Codes'