[UBL-SR-44]-An Invoice may only have one unique PaymentID, but the PaymentID may be used for multiple PaymentMeans
UBL-SR-44pxs-taxdata:TaxData/pxs-taxdata:ReportedTransaction/pxs-taxdata:ReportedDocumentcount(//cbc:PaymentID[not(preceding::cbc:PaymentID/. = .)]) <= 1