# PEPPOL-EN16931-CL006

Source: https://xmlvalid.com/rules/PEPPOL-EN16931-CL006

> Invoice period description code must be according to UNCL 2005 D.16B.

- Level: error
- Rule sets: Peppol BIS Billing 3.0 rules 3.0.21
- Context: `cac:InvoicePeriod/cbc:DescriptionCode`
- Test: `some $code in $UNCL2005 satisfies normalize-space(text()) = $code`

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