UBL-SR-06
Preceding invoice reference shall occur maximum once
What does this rule mean?
Preceding invoice reference shall occur maximum once
A syntax rule binding the EN 16931 requirements to the concrete XML syntax (UBL or CII).
Official rule message (standard)
Preceding invoice reference shall occur maximum once
Where the rule applies
Syntax: UBL
Affected element (XPath):
cac:BillingReference
Technical test
The rule passes when this Schematron expression holds true:
(count(cac:InvoiceDocumentReference) <= 1)How to fix it
A missing or incorrect business entry only you can supply. Add or correct it, then re-check.
Adjust the named element/attribute to the syntax requirement.
Correct the affected entry in your XML, then re-check the invoice. Validation runs locally in your browser — your file never leaves your machine.
Check an e-invoice here
Drop an XML or ZUGFeRD PDF file here. Validation runs locally in your browser against EN 16931 — your file never leaves your machine.