An identifier of a referenced purchase order, issued by the Buyer. An invoice must have buyer reference (BT-10) or purchase order reference. In cases where sales order reference is provided, but there's no purchase order reference, then use value "NA" as this element is mandatory in UBL

Cardinality
1..1
Namespace
cbc urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2
Data type
Document Reference
Example value
98776
Business terms
BT-13
Rules
Identifier/Error message Flag
PEPPOL-EN16931-R003
A buyer reference or purchase order reference MUST be provided.
fatal