# BT-142 Invoice line item standard identifier

An identifier for the item as published in a product classification scheme or standard.

## Quick answer

An identifier for the item as published in a product classification scheme or standard.

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

## In plain language

An identifier for the item as published in a product classification scheme or standard.

An identifier for the item as published in a product classification scheme or standard.

Used for standardized product identification across systems.

## What you usually enter here

Standard product identifier (EAN, GTIN, etc.)

Typical valid values include: 1234567890123, EAN:1234567890123, GTIN:1234567890123

Optional according to EN 16931-1.

## What goes wrong often

Avoid values like: , AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

Relevant rule codes: BR-2

## Examples in context

Used for standardized product identification across systems.

Optional according to EN 16931-1.

## Valid Examples

- 1234567890123
- EAN:1234567890123
- GTIN:1234567890123

## Invalid Examples

- AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

## Related Fields

Used for standardized product identification across systems.

- [BT-138 Invoice line item name](/resources/xrechnung/bt-138-invoice-line-item-name)
- [BT-139 Invoice line item description](/resources/xrechnung/bt-139-invoice-line-item-description)
- [BT-140 Invoice line item seller's identifier](/resources/xrechnung/bt-140-invoice-line-item-sellers-identifier)
- [BT-141 Invoice line item buyer's identifier](/resources/xrechnung/bt-141-invoice-line-item-buyers-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-142

### Data Type:
identifier

### Cardinality:
0..1

### Requirement:
Optional

### Max Length:
50 characters

### Since Version:
Optional

## XML Implementation

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

### CII (UN/CEFACT) Syntax
```
/CrossIndustryInvoice/SupplyChainTradeTransaction/ApplicableHeaderTradeSettlement/ram:SpecifiedTradeSettlementLineMonetarySummation/ram:SpecifiedTradeProduct/ram:StandardItemIdentification/ram:ID
```

## Validation Rules

### BR-2
BR-2

## Why the standard cares about this field

### Business Context
Used for standardized product identification across systems.

### Legal Requirement
Optional according to EN 16931-1.

## 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)