warningEN 16931syntax binding ruleUBL
A UBL invoice shall not include the Invoice ID scheme identifier
The invoice number carries a schemeID attribute.
Remove schemeID from cbc:ID. The invoice number is a plain string; there is no scheme for it.
UBL — context /ubl:Invoice | /cn:CreditNote
not(cbc:ID/@schemeID)
Nothing is stored, and the whole invoice is checked, not just this rule. A PDF only works if it is Factur-X / ZUGFeRD — a PDF with the invoice XML inside it.