# BT-123 Supporting Document Description

A short text describing the supporting document.

## Quick answer

> **Taxes and totals**: VAT treatment, tax breakdowns, and document totals that validators check closely.

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-123)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-123)

## In plain language

A short text describing the supporting document.

A short text describing the supporting document.

Helps buyers understand what the referenced or attached document contains.

## What you usually enter here

Free text document description

Typical valid values include: Signed contract, Delivery note, Timesheet for May 2026

Optional EN 16931 supporting document context.

## What goes wrong often

Avoid values like:

## Examples in context

Helps buyers understand what the referenced or attached document contains.

Optional EN 16931 supporting document context.

## Valid Examples

- Signed contract
- Delivery note
- Timesheet for May 2026

## Related Fields

Helps buyers understand what the referenced or attached document contains.

- [BT-122 Supporting Document Reference](/resources/xrechnung/bt-122-supporting-document-reference)
- [BT-124 External Document Location](/resources/xrechnung/bt-124-external-document-location)
- [BT-125 Attached Document](/resources/xrechnung/bt-125-attached-document)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-123

### Data Type:
text

### Cardinality:
0..1

### Requirement:
Optional

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:AdditionalDocumentReference/cbc:DocumentDescription
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeAgreement/ram:AdditionalReferencedDocument/ram:Name
```

## Create an XRechnung from your PDF

The converter reads the invoice and shows the fields it found before download, so you can check and correct the values. No PDF? Fill in the XRechnung directly in the form.

- [Convert invoice](/en/pdf-to-xrechnung)
- [Fill in XRechnung in the form](/en/create-xrechnung)

Download requires an account. Subscriptions from €10/month with annual billing (excl. taxes), or €5 per conversion (excl. taxes) without a subscription.

## Why the standard cares about this field

### Business Context
Helps buyers understand what the referenced or attached document contains.

### Legal Requirement
Optional EN 16931 supporting document context.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)