Validation rules

BR-DEX-01

An attached document (BT-125) uses a MIME type outside the list the Extension permits (the CIUS list plus application/xml).

Rule: BR-DEX-01 — official EN 16931 / XRechnung rule
Severity: error
Detected by: tier 3 — KoSIT validator (authoritative)
Reachability: Only reachable when validating your own XML — normbill-generated documents cannot trigger it

Belongs to the 'Extension XRechnung' CustomizationID. normbill generates the plain CIUS, never the Extension — reachable only for Extension XML submitted to /v1/invoices/validate.

How to fix it

Use one of the permitted MIME types for the attachment.

BR-DEX-01 auf Deutsch — was bedeutet der Fehler?

Eine Anlage (BT-125) verwendet einen MIME-Typ außerhalb der zulässigen Liste (CIUS-Liste plus application/xml). Diese Regel gehört zur „Extension XRechnung“; normbill erzeugt die reguläre CIUS.

So beheben Sie den Fehler

Verwenden Sie einen zulässigen MIME-Typ.

Official sources

Every 422 from the API lists the rule id, the path in your request JSON, a plain-language message and a suggested fix — see the docs overview for the report format.

Or try it live: drop any XRechnung XML on the free validator — same KoSIT-backed report, no account.