In this attribute Icecat stores the mapped product code, which (sometimes) differs from the one supplied in prod_id (conforming to distributor data).
You can use the following rule: when products have the same m_prod_id, they are treated as the same product in Icecat.
Note: there can be multiple EAN / UPC codes per product, because per packaging variation a new code is published.
Further, dependent on logistic processing and import/export sometimes different codes are given out per region.
If you have upgraded to a Full Icecat account, you can download XML data from the location below: https://data.icecat.biz/export/export_gz You can download CSV data from the locations below: https://data.icecat.biz/export/export_gz https://data.icecat.biz/export/export_gz Information about the categories we use, can be found here: https://data.icecat.biz/export/gz Sometimes distributors give their own interpretation of brand product codes, instead of using the original ones.