# BR-01

Source: https://xmlvalid.com/rules/BR-01

> An Invoice shall have a Specification identifier (BT-24).   

- Level: error
- Rule sets: EN 16931 rules (UBL) 1.3.17, EN 16931 rules 1.3.16 (UBL), EXTENDED-CTC-FR rules (UBL) 1.4.0.04
- Context: `/ubl:Invoice | /cn:CreditNote`
- Test: `normalize-space(cbc:CustomizationID) != ''`

> An Invoice shall have a Specification identifier (BT-24).

- Level: error
- Rule sets: EN 16931 rules (CII) 1.3.17, EN 16931 rules 1.3.16 (CII), EXTENDED-CTC-FR rules (CII) 1.4.0.04
- Context: `/rsm:CrossIndustryInvoice`
- Test: `normalize-space(rsm:ExchangedDocumentContext/ram:GuidelineSpecifiedDocumentContextParameter/ram:ID) != ''`

> An Invoice shall have a Specification identifier (BT-24).   

- Level: error
- Rule sets: Romanian RO e-Factura rules (UBL) 1.0.9
- Context: `/ubl:Invoice | /cn:CreditNote`
- Test: `(cbc:CustomizationID) != ''`

> An Invoice shall have a Specification identifier (BT-24).

- Level: error
- Rule sets: Factur-X BASIC WL rules 1.09, Factur-X EN 16931 rules 1.09.2, Factur-X EXTENDED rules 1.09.2
- Context: `/rsm:CrossIndustryInvoice`
- Test: `(rsm:ExchangedDocumentContext/ram:GuidelineSpecifiedDocumentContextParameter/ram:ID != '')`

## Why it fails

- The invoice has no `cbc:CustomizationID` (`ram:GuidelineSpecifiedDocumentContextParameter/ram:ID` in CII), the identifier of the specification it follows.

## How to fix it

- Add the identifier of the specification the invoice is made for: `urn:cen.eu:en16931:2017` for plain EN 16931, or the longer identifier of a CIUS such as Peppol BIS (`urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0`) or XRechnung.

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