# PEPPOL-COMMON-R040

Source: https://xmlvalid.com/rules/PEPPOL-COMMON-R040

> GLN must have a valid format according to GS1 rules.

- Level: error
- Rule sets: Peppol BIS Billing 3.0 rules 3.0.21, Peppol Order rules 3.7, Peppol Order Response rules 3.2, Peppol Despatch Advice rules 3.5, Peppol Catalogue rules 3.5, Peppol Catalogue Response rules 3.0, Peppol Invoice Response rules 3.1, Peppol Message Level Response rules 3.0, Peppol Order Change rules 3.2, Peppol Order Cancellation rules 3.0
- Context: `cbc:EndpointID[@schemeID = '0088'] | cac:PartyIdentification/cbc:ID[@schemeID = '0088'] | cbc:CompanyID[@schemeID = '0088']`
- Test: `matches(normalize-space(), '^[0-9]+$') and u:gln(normalize-space())`

## Why it fails

- A GLN (scheme `0088`) has a wrong check digit, or contains spaces or letters.
- Another identifier, such as a VAT number, was sent with scheme `0088`.

## How to fix it

- Check the GLN with GS1's check digit calculator, or use the scheme that matches the identifier you have.

Validate a document against these rules: https://xmlvalid.com/validate