fatalEN 16931syntax binding ruleUBL
Preceding invoice reference shall occur maximum once
'Preceding invoice reference' appears more than once, and this profile allows it at most once.
Keep the single correct 'Preceding invoice reference' and delete the rest. Repeating an element that the semantic model treats as singular is usually a serialiser writing every value it has instead of choosing one.
UBL — context cac:BillingReference
(count(cac:InvoiceDocumentReference) <= 1)