# BT-157 Item Standard Identifier

A standard identifier for the item, such as a GTIN. The identifier must carry a scheme identifier attribute from the ISO 6523 ICD list, for example 0160 for GTIN.

## Quick answer

> **Line items**: The goods or services on each invoice line, including quantities, prices, and VAT.

- [Validate XML](/en/xrechnung-validator?source=resource&bt=BT-157)
- [Convert invoice](/en/pdf-to-xrechnung?source=resource&bt=BT-157)

## In plain language

A standard identifier for the item, such as a GTIN. The identifier must carry a scheme identifier attribute from the ISO 6523 ICD list, for example 0160 for GTIN.

A standard identifier for the item, such as a GTIN. The identifier must carry a scheme identifier attribute from the ISO 6523 ICD list, for example 0160 for GTIN.

Identifies the invoiced goods or services for buyer, seller, and automated procurement or inventory matching.

## What you usually enter here

Standard item identifier

Typical valid values include: 4006381333931

Defined by EN 16931 for invoice line item identification; mandatory item names and optional identifiers must follow the listed scheme and country code rules.

## What goes wrong often

Avoid values like:

Relevant rule codes: BR-64, BR-CL-21

## Examples in context

Identifies the invoiced goods or services for buyer, seller, and automated procurement or inventory matching.

Defined by EN 16931 for invoice line item identification; mandatory item names and optional identifiers must follow the listed scheme and country code rules.

## Valid Examples

- 4006381333931

## Related Fields

Identifies the invoiced goods or services for buyer, seller, and automated procurement or inventory matching.

- [BT-155 Invoice Line Item Seller Identifier](/resources/xrechnung/bt-155-invoice-line-item-sellers-identifier)
- [BT-156 Buyer Item Identifier](/resources/xrechnung/bt-156-buyer-item-identifier)
- [BT-158 Item Classification Identifier](/resources/xrechnung/bt-158-item-classification-identifier)

## 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-157

### Data Type:
identifier

### Cardinality:
0..1

### Requirement:
Optional

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:InvoiceLine/cac:Item/cac:StandardItemIdentification/cbc:ID
```

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/IncludedSupplyChainTradeLineItem/SpecifiedTradeProduct/GlobalID
```

## Validation Rules

### BR-64
BR-64

### BR-CL-21
BR-CL-21

## Check whether your XRechnung sets BT-157 correctly

Upload the XML file to the free validator. It applies the KoSIT rules for XRechnung 3.0 and names each finding with its rule ID, for this field for example BR-CL-21, BR-64. Creating a new invoice instead? The converter checks the invoice against the same rules and shows the findings before download.

- [Validate XML](/en/xrechnung-validator)
- [Convert invoice](/en/pdf-to-xrechnung)

Free, no account needed. XML file up to 2 MB.

## Why the standard cares about this field

### Business Context
Identifies the invoiced goods or services for buyer, seller, and automated procurement or inventory matching.

### Legal Requirement
Defined by EN 16931 for invoice line item identification; mandatory item names and optional identifiers must follow the listed scheme and country code rules.

## FAQ

### Where does the scheme identifier of BT-157 go?
The scheme identifier is an attribute of BT-157, not a separate business term. In UBL it is cbc:ID/@schemeID in cac:StandardItemIdentification, and in CII it is ram:GlobalID/@schemeID. BR-64 requires the attribute whenever BT-157 is present, and BR-CL-21 requires an ISO 6523 ICD code, for example 0160 for a GTIN.

## 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)