If You have a Danish company and do not have a GLN No. specified in the Company Setup, then export of all electronic documents, incl. PEPPOL BIS 3.0 will be using the company's VAT no. as identifier in the electronic documents. There is, however, an error with the PEPPOL BIS 3.0 format export which does not write the SchemeID in the CompanyID section of the PEPPOL file which is mandatory for Danish suppliers. This is the error message an online validator like https://anskaffelser.dev/service/validator/ will give when trying to validate the file.

DK-R-014 For Danish Suppliers it is mandatory to specify schemeID as "0184" (DK CVR-number) when PartyLegalEntity/CompanyID is used for AccountingSupplierParty

This is a critical error.

However, there is also another "feature" which is very inconvenient. The schemeID 0184 used in Denmark, requires that "DK" is prefixed in the VAT no. when using the VAT No. as Company Identifier in electronic documents. If you have specified your company's VAT No. as i.e. 77777777 in the Company Setup or using the same syntax on the customer card, then it will write that exact value to the electronic file. Writing the VAT No. without DK prefixed is standard practice in Denmark but for the electronic documents, it is mandatory to prefix with a DK.

It would be a very welcome feature if the export made sure to prefix with DK, when country code is DK, both for AccountSupplierParty and for AccountingCustomerParty. The feature would, however, need to not prefix DK if the source data already has DK prefixed.