Message

Element 'cbc:ID' MUST be unique.

Context
/ubl:ApplicationResponse/cac:DocumentResponse/cac:DocumentReference
Test
count(distinct-values(cac:DocumentReference/cbc:UUID)) = count(cac:DocumentReference/cbc:ID)
Usage
/ ubl:ApplicationResponse / cac:DocumentResponse / cac:DocumentReference
/ ubl:ApplicationResponse / cac:DocumentResponse / cac:DocumentReference / cbc:UUID