If you need to add some Salesheader reference from Business Central to the

PEPPOL , following options can be used

<cac:AdditionalDocumentReference>

 <cbc:ID schemeID="AMH">Case-123456</cbc:ID> <cbc:DocumentTypeCode>130</cbc:DocumentTypeCode> </cac:AdditionalDocumentReference>

AMH – Sagsnummer (Case number)
AEP – Projektnummer (Project number)
AKZ – Policenummer (Policy number)
AEV – Aflæsningssted (Metering point)
ARR – Personnummer (Social security number)
AWV – Telefonnummer (Phone number)
BW – Batch/Lot nummer (Batch/lot/package number)
UAR – Serienummer (Serial number)