> For the complete documentation index, see [llms.txt](https://helpcenter.channable.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://helpcenter.channable.com/manage-improve-product-data/rules-bulk-edit-and-enrich/how-to-use-conditions-if-in-rules/rule-condition-invalid-gtin-or-ean.md).
# Rule condition: Invalid GTIN or EAN
### Use cases
* Detect and exclude items with invalid GTINs or EANs (for some channels, such as Amazon, GTINs or EANs are mandatory)
### is valid
Use the **is valid** action to check that GTIN or EAN values are valid. The correct GTIN format is eight, twelve, thirteen or fourteen digits.
### is not valid
Use the **is not valid** action to check if the GTIN or EAN format is correct. This action [calculates a check digit](https://www.gs1.org/services/check-digit-calculator) (which makes sure the barcode is put together correctly).
{% hint style="info" %}
In **Setup > Edit mapping**, make sure the field is mapped correctly and is the correct type, as these actions can only be used for GTIN and EAN fields.
{% endhint %}
---
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