UBL-CR-666: An invoiced object reference must not carry an attachment

What it means

In a UBL file, cac:AdditionalDocumentReference is used for two different things. With document type code 130 it holds the invoiced object identifier (BT-18). Without that code it describes a supporting document (BG-24), which can have an attachment: an embedded file (BT-125) or a link to one (BT-124). This rule checks that a reference with code 130 has no cac:Attachment.

Why it matters

This rule is an error, not a warning. A reference with code 130 is read as an identifier only, and a supporting document is read from a reference without that code. When one reference tries to be both, the file breaks the EN 16931 UBL rules.

How to fix it

In your invoicing software, check the references and attached documents on the invoice. Keep the invoiced object reference, such as a subscription number or a meter point, as one reference with no file attached to it. Add the PDF or other supporting document separately, as its own supporting document. If you build the XML yourself, remove cac:Attachment from the cac:AdditionalDocumentReference that has cbc:DocumentTypeCode 130 and put it in another cac:AdditionalDocumentReference without that code.

The rule as published

A UBL invoice shall not include an AdditionalDocumentReference simultaneously referring an Invoice Object Identifier and an Attachment

Where this rule applies