cac:InvoiceLine/cac:Item/cac:StandardItemIdentification/cbc:ID | cac:CreditNoteLine/cac:Item/cac:StandardItemIdentification/cbc:ID[BR-64]-The Item standard identifier (BT-157) shall have a Scheme identifier.
Hitting this rule in production? Paste the invoice into the validator or wire the API into CI so it never ships broken again.