Using DUNS+4 ID type for Rosettanet Implementation

Can anyone tell me if I could use “DUNS+4” ID type in Rosettanet integration.
As expected my enterprise has only One DUNS number but different internal application like Order management, Invoicing etc…
I intend to use the 4 Digit number to identify the internal application.

The problem is, if I use DUNS+4 in globalPartnerIdentifier tag then the validation of the document fails.
Is it compulsory is use DUNS and no other type of TN ID for rosettanet?

Any help is greatly appreciated