fatalPeppol BIS Billing 3.0profileCII
Only one invoiced object is allowed on document level
More than one invoiced object reference (BT-18) at document level.
Keep one, or move the extra references onto the relevant invoice lines (BT-128).
CII — context ram:ApplicableHeaderTradeAgreement
count(ram:AdditionalReferencedDocument[ram:TypeCode='130']) <=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.