The specification identifier is not the XRechnung one

`Specification identifier` (BT-24) should carry the URN of the XRechnung standard: the CIUS, its extension, or the CVD profile.

Only the issuer holds this value: Factlint reports it and never fabricates it. Test your invoice to find out whether it is affected.

Why this error happens

The common case is not a missing URN but a stale one — from an earlier XRechnung version, or the bare EN 16931 URN. The document is then judged against rules it does not claim to follow, which explains findings that seem to come out of nowhere.

How to fix it

Have your generator write the expected URN. Factlint does not replace it, even though only one value is correct: rewriting BT-24 would make the document *declare* conformance to a CIUS its issuer never claimed. That is what separates this case from `BR-01`, where a missing URN follows from what the document actually contains.

XML correction example

BEFORE (invalid)

<ram:ID>urn:cen.eu:en16931:2017</ram:ID>

AFTER (compliant)

<ram:ID>urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0</ram:ID>