DE-R-017
If both supplier and customer are located in Germany, the element "Invoice type code" (BT-3) should only contain the following values from code list UNTDID 1001: 326 (Partial invoice), 380 (Commercial invoice), 384 (Corrected invoice), 389 (Self-billed invoice), 381 (Credit note), 875 (Partial construction invoice), 876 (Partial final construction invoice), 877 (Final construction invoice).
What the rule checks
As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.
(/ubl-invoice:Invoice | /ubl-creditnote:CreditNote)[$supplierCountryIsDE and $customerCountryIsDE]
normalize-space(cbc:InvoiceTypeCode) = $supportedInvAndCNTypeCodes or normalize-space(cbc:CreditNoteTypeCode) = $supportedInvAndCNTypeCodes
Checked with Peppol BIS Billing 3.0 Invoice, Peppol BIS Billing 3.0 Credit Note