This table explains the data between CatchFeeder and Shopify


CatchFeeder Data   Shopify DataCatch Marketplace Data
SKU    This is the Shopify product ID - a number generated by Shopify when you create a product
Retailer Reference    This is the Shopify Variant ID - a number generated by Shopify when you create a product
MPN    This is the Variant SKU from ShopifyMPN Field in Catch
UPC
From the field labelled Barcode (ISBN, UPC, GTIN, etc.) in ShopifyUPC field in Catch