fatalEN 16931syntax binding ruleUBL
Contract identifier shall occur maximum once.
'Contract identifier' appears more than once, and this profile allows it at most once.
Keep the single correct 'Contract identifier' 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 /ubl:Invoice | /cn:CreditNote
(count(cac:ContractDocumentReference/cbc:ID) <= 1)