Message

cac:PartyIdentification/cbc:ID SHOULD NOT have any attributes but schemeID

Context
ubl:Enquiry/cac:RequestorParty/cac:PartyIdentification/cbc:ID
Test
not(./@*[not(name()='schemeID')])
Usage
/ t009:Enquiry / cac:RequestorParty / cac:PartyIdentification / cbc:ID