Value MUST be part of code list 'Country codes (ISO 3166-1:Alpha2)'.
/ubl:OrderChange/cac:AccountingCustomerParty/cac:Party/cac:PartyLegalEntity/cac:RegistrationAddress/cac:Country/cbc:IdentificationCode
(some $code in $clISO3166 satisfies $code = normalize-space(text()))