> ## Knowledge Base Index
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> Use this file to discover available pages before exploring further.
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# Validating your catalog structure - Amazon Marketplace Plus

It is essential to apply a consistent methodology when creating your products: defining references, assigning EAN codes, etc.  
This ensures a well-structured catalog for both internal use and external platforms such as marketplaces.

On Amazon, the **Reference** field in PrestaShop is used as the **SKU** (unique internal identifier).  
This field is necessary to identify your offers and import orders.

⚠️ If the **Reference** field is empty, incorrect, or used multiple times in your catalog, synchronizations and imports will not work properly.

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### Case #1 – Product with combinations

In the **Details** tab, only the **Reference** field is required. This field will be used as the **SKU** on Amazon:

![PrestaShop Amazon Marketplace example reference](https://storage.crisp.chat/users/helpdesk/website/-/3/f/a/8/3fa8ee645cd13200/screenshot1120_1sri8f4.jpg)

In the **Combinations** tab, you must enter a **unique Reference (SKU)** and an **EAN or UPC code** for each variation:

![PrestaShop Amazon Marketplace EAN and reference](https://storage.crisp.chat/users/helpdesk/website/-/3/f/a/8/3fa8ee645cd13200/screenshot1121_1vibrn9.jpg)

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### Case #2 – Product without combinations

For simple products (without combinations), you only need to fill in the **Reference (SKU)** and the **EAN**:

![PrestaShop Amazon Marketplace no combinations](https://storage.crisp.chat/users/helpdesk/website/-/3/f/a/8/3fa8ee645cd13200/screenshot1122_1noq1h4.jpg)

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### Bulk update (if needed)

If your catalog does not meet these requirements, you can use the [Tools](https://doc.common-services.com/en/article/product-references-and-eanupc-codes-importexport-tool-amazon-marketplace-plus-1flimr0/) tab in the module configuration to update product references in bulk (e.g., via Excel).

> **🔎 Note:**  
> The **Reference** field in PrestaShop corresponds to the **SKU** on Amazon.  
> Using unique references ensures precise product listing on marketplaces.