# DT-CIUS-PT-018

Source: https://xmlvalid.com/rules/DT-CIUS-PT-018

> The BT-19 does not meet the defined format: alphanumeric with size between 1 and 50.

- Level: error
- Rule sets: CIUS-PT rules (Portugal, UBL) 2.1.1
- Context: `//ubl:Invoice/cbc:AccountingCost | //cn:CreditNote/cbc:AccountingCost`
- Test: `matches(.,'^(.{1,50})$')`

Validate a document against these rules: https://xmlvalid.com/validate