Specification identifier MUST start with the value 'urn:peppol:pint:billing-3.0@jp:peppol-1'.
/ubl:Invoice[cac:AccountingSupplierParty/cac:Party/cac:PostalAddress/cac:Country/cbc:IdentificationCode = 'JP' ]
starts-with(normalize-space(cbc:CustomizationID/text()), 'urn:peppol:pint:billing-3.0@jp:peppol-1')