[IBR-080-OM] - When Item classification identifier (IBT-158) is provided with @listID='HS', it must be exactly 12 digits (Oman HS code). 6-digit ISIC codes are validated separately under CL-08-OM-ISIC and 8-digit service-type codes under CL-12-OM.
IBR-080-OMcac:InvoiceLine | cac:CreditNoteLinenot(cac:Item/cac:CommodityClassification/cbc:ItemClassificationCode[@listID='HS']) or string-length(normalize-space(cac:Item/cac:CommodityClassification/cbc:ItemClassificationCode[@listID='HS'])) = 12