Message

A scheme identifier for the credit note line item registered identifier MUST be provided if credit note line item registered identifiers are used to identify a product.(e.g. GTIN)

Context
//cac:CreditNoteLine
Test
(cac:Item/cac:StandardItemIdentification/cbc:ID/@schemeID) or not(cac:Item/cac:StandardItemIdentification)
Usage
/ ubl:CreditNote / cac:CreditNoteLine / cac:Item / cac:StandardItemIdentification / cbc:ID / @schemeID