warningEN 16931syntax binding ruleCII
Only one SpecifiedTradePaymentTerms should be present
More than one SpecifiedTradePaymentTerms group is present on the invoice. EN 16931 gives this a single value, so a receiver has no rule for choosing between the copies. This one is reported as a warning, not an error: the invoice still passes EN 16931, but which copy a receiving system picks is undefined and some will refuse it. EN 16931 has one set of payment terms (BT-20) per invoice; several payment options belong in repeated PaymentMeans, not in repeated terms.
Keep the one SpecifiedTradePaymentTerms group that is correct and delete the others. Repeated singular elements almost always come from a serialiser emitting every value it holds instead of choosing one — fix it at the source, not by trimming the output file.
CII — context /rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeSettlement
count(ram:SpecifiedTradePaymentTerms) <= 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.