# BR-DE-15 Leitweg-ID must be provided

The Leitweg-ID (routing ID) must be provided to identify the transmission path for German e-invoices.

## Problem Description

The Leitweg-ID (routing ID) must be provided to identify the transmission path for German e-invoices.

> **ERROR**: XRechnung 3.0

## Context and Significance

The Leitweg-ID is required by German tax authorities to track the transmission path of electronic invoices. It helps ensure the authenticity and integrity of the invoice during transmission through various systems.

## Solution

Add a valid Leitweg-ID in the format " Leitweg-ID: [identifier]" to the invoice header.

## Valid Examples

- Leitweg-ID: 123456789012345678901234567890123456789012345678
- Leitweg-ID: DE123456789

## Invalid Examples

- Missing Leitweg-ID completely
- Leitweg-ID: (empty)
- Invalid format or characters

## Code Examples

### Valid XML
```
<cbc:Note>Leitweg-ID: 123456789012345678901234567890123456789012345678</cbc:Note>
<cac:AdditionalDocumentReference>
  <cbc:ID>Leitweg-ID</cbc:ID>
  <cbc:DocumentTypeCode>130</cbc:DocumentTypeCode>
  <cac:Attachment>
    <cbc:EmbeddedDocumentBinaryObject mimeCode="text/plain">MTIzNDU2Nzg5MDEyMzQ1Njc4OTAxMjM0NTY3ODkwMTIzNDU2Nzg5MDEyMzQ1Njc4</cbc:EmbeddedDocumentBinaryObject>
  </cac:Attachment>
</cac:AdditionalDocumentReference>
```

### Invalid XML
```
<!-- Missing Leitweg-ID completely -->
<cac:Invoice>
  <!-- No Leitweg-ID reference -->
</cac:Invoice>
```

## Technical Details

### Affected Fields
Invoice Notes, Additional Document References

## Related Rules

- [BR-DE-16](/resources/kosit-validator-errors/br-de-16-business-process-type-must-be-provided)
- [BR-DE-17](/resources/kosit-validator-errors/br-de-17-object-identifier-must-be-provided)

## 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.