# BR-DEX-04 Party identifier scheme must use an ISO 6523 code

Any scheme identifier on a party identifier (Seller BT-29, Buyer BT-46, Payee BT-60) must be coded using one of the ISO 6523 ICD code list entries.

## Problem Description

Any scheme identifier on a party identifier (Seller BT-29, Buyer BT-46, Payee BT-60) must be coded using one of the ISO 6523 ICD code list entries.

> **ERROR**: XRechnung 3.0

## Context and Significance

This XRechnung Extension rule fires only in the Extension scenario, which relaxes the core severity to permit additional ISO 6523 scheme codes (such as DIGA identifiers) for party identifiers.

## Solution

Set the @schemeID on cac:PartyIdentification/cbc:ID to a valid ISO 6523 ICD value (for example 0088 for GLN). If you do not need Extension identifiers, the standard XRechnung CIUS profile avoids this rule.

- validate
- convert

## Valid Examples

- <cbc:ID schemeID="0088">4012345000009</cbc:ID>

## Invalid Examples

- <cbc:ID schemeID="XYZ">4012345000009</cbc:ID> — XYZ is not an ISO 6523 code

## Code Examples

### Valid XML
```
<cac:PartyIdentification>
  <cbc:ID schemeID="0088">4012345000009</cbc:ID>
</cac:PartyIdentification>
```

### Invalid XML
```
<cac:PartyIdentification>
  <cbc:ID schemeID="XYZ">4012345000009</cbc:ID>
</cac:PartyIdentification>
```

## Affected Fields

- [BT-29 Seller identifier](/resources/xrechnung/bt-29-seller-identifier)
- [BT-46 Buyer identifier](/resources/xrechnung/bt-46-buyer-identifier)
- [BT-60 Payee identifier](/resources/xrechnung/bt-60-payee-identifier)

## Related Rules

- [BR-DEX-05](/resources/kosit-validator-errors/br-dex-05-legal-registration-iso-6523-scheme)
- [BR-DE-21](/resources/kosit-validator-errors/br-de-21-specification-identifier-syntax)

## Validation Tools

- [Official KoSIT Validator](https://erechnungsvalidator.service-bw.de/): Validate your XRechnung files against all BR-DE rules.
- [Convert PDF to XRechnung](/pdf-to-xrechnung): Automatic validation error fixes when converting.

## Related Resources

- [Official Specification](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)
- [Complete Error List](/resources/kosit-validator-errors): Overview of all German XRechnung validation rules.