# BT-123 Supporting Document Description

A short text describing the supporting document.

## Quick answer

A short text describing the supporting document.

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

- validate
- convert

## 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
```

## 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/)
- [Invoice Converter](/pdf-to-xrechnung)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)