fatalEN 16931syntax binding ruleUBLBG-18
An Invoice shall contain maximum one Payment Card account (BG-18).
More than one payment card group (BG-18).
Keep a single card account. An invoice states one way to pay.
UBL — context /ubl:Invoice | /cn:CreditNote
count(cac:PaymentMeans/cac:CardAccount) <= 1
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.