# BR-DE-21

Source: https://xmlvalid.com/rules/BR-DE-21

> Das Element "Specification identifier" (BT-24) soll syntaktisch der Kennung des Standards XRechnung entsprechen.

- Level: warning
- Rule sets: XRechnung 3.0 rules (UBL) 2.6.0
- Context: `/ubl:Invoice | /cn:CreditNote`
- Test: `cbc:CustomizationID = $XR-CIUS-ID or cbc:CustomizationID = $XR-EXTENSION-ID or cbc:CustomizationID = $XR-CVD-ID`

> Das Element "Specification identifier" (BT-24) soll syntaktisch der Kennung des Standards XRechnung entsprechen.

- Level: warning
- Rule sets: XRechnung 3.0 rules (CII) 2.6.0
- Context: `/rsm:CrossIndustryInvoice/rsm:ExchangedDocumentContext`
- Test: `ram:GuidelineSpecifiedDocumentContextParameter/ram:ID = $XR-CIUS-ID or ram:GuidelineSpecifiedDocumentContextParameter/ram:ID = $XR-EXTENSION-ID or ram:GuidelineSpecifiedDocumentContextParameter/ram:ID = $XR-CVD-ID`

## Why it fails

- The specification identifier (BT-24) is not the XRechnung one: the invoice declares plain EN 16931, Peppol BIS, Factur-X or an older XRechnung version.

## How to fix it

- For XRechnung 3.0 use `urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0` in `cbc:CustomizationID` (`ram:GuidelineSpecifiedDocumentContextParameter/ram:ID` in CII). If the invoice is meant to be Peppol BIS, validate it against the Peppol profile instead.

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