DT-CIUS-PT-032.2
The BT-34 identification scheme 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:AccountingSupplierParty/cac:Party/cbc:EndpointID | //cn:CreditNote/cac:AccountingSupplierParty/cac:Party/cbc:EndpointID
(exists(@schemeID) and not(matches(@schemeID,'^(.{1,20})$')))
Checked with Portugal CIUS-PT Invoice (UBL), Portugal CIUS-PT Credit Note (UBL)