An identification of the specification containing the total set of rules regarding semantic content, cardinalities and business rules to which the data contained in the instance document conforms.

Cardinality
1..1
Namespace
cbc urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2
Data type
Identifier
Default value
urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0
Business terms
BT-24
Rules
Identifier/Error message Flag
PEPPOL-EN16931-R004
Specification identifier MUST have the value 'urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0'.
fatal
BR-01
An Invoice shall have a Specification identifier (BT-24).   
fatal