An attached tendering request or files which must be referenced by an cac:AdditionalDocumentReference

cac urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2
Data type
Child elements
Card Name Description
1..1 cac:ExternalReference

External reference
An external reference to place your questions or add an attachment to express questions in more detail. There must be only one kind of reference a file or questions.