Message

A unit code attribute MUST have a unit code list identifier attribute 'UNECERec20'.

Context
//*[contains(name(),'Quantity')]
Test
not(attribute::unitCode) or (attribute::unitCode and attribute::unitCodeListID = 'UNECERec20')
Usage
/ ubl:Invoice / cac:InvoiceLine / cbc:InvoicedQuantity / @unitCodeListID