# BR-CL-13 Item classification scheme must come from UNTDID 7143

The item classification identifier scheme identifier (BT-158-1) must be a code from the UNTDID 7143 list.

## Problem Description

The item classification identifier scheme identifier (BT-158-1) must be a code from the UNTDID 7143 list.

> **ERROR**: XRechnung 3.0

## Context and Significance

This EN16931 core code-list rule identifies which classification catalogue a coded item belongs to.

## Solution

Set the listID to a valid UNTDID 7143 code such as SRV (GS1 GPC) or STI (CPV); do not use a plain scheme name.

- validate
- convert

## Valid Examples

- BT-158-1 = SRV — GS1 Global Product Classification
- BT-158-1 = STI — CPV procurement vocabulary

## Invalid Examples

- BT-158-1 = GPC — not a UNTDID 7143 code
- BT-158-1 = CUSTOM — free-text scheme

## Code Examples

### Valid XML
```
<cac:CommodityClassification>
  <cbc:ItemClassificationCode listID="STI">30192700</cbc:ItemClassificationCode>
</cac:CommodityClassification>
```

### Invalid XML
```
<cac:CommodityClassification>
  <cbc:ItemClassificationCode listID="CPV">30192700</cbc:ItemClassificationCode>
</cac:CommodityClassification>
```

## Affected Fields

- [BT-158-1 Item classification identifier scheme identifier](/resources/xrechnung/bt-158-item-standard-identifier-scheme)

## Related Rules

- [BR-CL-21](/resources/kosit-validator-errors/br-cl-21-iso-6523-item-standard-scheme)

## 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.