BR-64: The Item standard identifier (BT-157) shall have a Scheme identifier

This fatal rule requires that when an item standard identifier (BT-157) is provided, it carries a scheme identifier. In UBL, the element cac:InvoiceLine/cac:Item/cac:StandardItemIdentification/cbc:ID (or the CreditNoteLine equivalent) must have the schemeID attribute present; the UBL test only checks existence, not whether its value is non-empty. In CII, for each //ram:IncludedSupplyChainTradeLineItem, if ram:SpecifiedTradeProduct/ram:GlobalID exists, its @schemeID must be present and have a non-whitespace value; if ram:GlobalID is absent, the rule passes. A document fails in UBL when the schemeID attribute is missing, and in CII when ram:GlobalID is present but its @schemeID is missing, empty, or whitespace-only.

In UBL, add a schemeID attribute to the cbc:ID element inside cac:StandardItemIdentification; the rule itself only checks that the attribute exists, but set it to the identifier of the scheme used. In CII, either remove ram:SpecifiedTradeProduct/ram:GlobalID if no item standard identifier is needed, or set its @schemeID to a non-whitespace value identifying the scheme. The rule does not define which scheme identifier values are allowed, so use a value from the applicable XRechnung code list for the item standard identifier scheme.