warningEN 16931syntax binding ruleCII
Only one SpecifiedTradePaymentTerms Description should be present
More than one payment terms description (BT-20) is present in SpecifiedTradePaymentTerms. 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. Several sentences of terms go in one element, separated by line breaks.
Keep the one payment terms description (BT-20) 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/ram:Description) <= 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.