DT-CIUS-PT-138.3
The BT-158 identification list version identifier does not meet the defined format: alphanumeric with size between 1 and 20.
What the rule checks
As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.
//ubl:Invoice/cac:InvoiceLine/cac:Item/cac:CommodityClassification/cbc:ItemClassificationCode | //cn:CreditNote/cac:CreditNoteLine/cac:Item/cac:CommodityClassification/cbc:ItemClassificationCode
(exists(@listVersionID) and not(matches(@listVersionID,'^(.{1,20})$')))
Checked with Portugal CIUS-PT Invoice (UBL), Portugal CIUS-PT Credit Note (UBL)