What is the logic for pushing SKU data in Razor to ebay?

Assets in Razor are pushed to M2E pro with the Razor SKU. However ebay does use SKU as one of its default fields. How is this data being remapped for eBay? Is it going into the "Custom Label" field?

Answer

When product from M2E is synced back and forth with eBay it is all tracked using the custom label fields.