When a self-billing Invoice or CreditNote message is enveloped, the value of the SBDH element Receiver/Identifier SHALL match the AccountingSupplierParty/Party/EndpointID element value, including the value of its schemeID attribute.
/p1:StandardBusinessDocument/p1:StandardBusinessDocumentHeader/p1:Receiver/p1:Identifier[$isSelfBilling]. = concat(/p1:StandardBusinessDocument/*/cac:AccountingSupplierParty/cac:Party/cbc:EndpointID/@schemeID, ':', normalize-space(/p1:StandardBusinessDocument/*/cac:AccountingSupplierParty/cac:Party/cbc:EndpointID))