BEAst: Used for T6099 - use code "220". In other cases - T6473 Document type external. Peppol: The type of reference. Must me part of UNCL1001. At least one of Document Type Code and Document Type must be used.

Namespace
cbc urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2
Data type
udt:CodeType
Example value
380
Code lists
Document name code, full list (UNCL1001)
Rules
Identifier/Error message Flag
PEPPOL-T128-R031
AdditionalDocumentReference SHALL contain a Document Type Code or a Document Type.
fatal
PEPPOL-T128-B02001
Value MUST be part of code list 'Document name code, full list (UNCL1001)'.
fatal