A few days ago there was an interesting discussion about utilizing Merchant SKUs (MSKUs) as an item analysis tool in Scanner Monkey, one of the paid Facebook Groups I belong to. A Merchant SKU is a unique identifier for your item on a listing. When you are listing via Seller Central the Seller (Merchant) SKU is found at the top of the offer tab. 
How is an MSKU different from an ASIN?
An ASIN is the Amazon Stock Identification Number which is the catalog number for a particular product LISTING within the Amazon database. The MSKU is a character string (letters/numbers) that relates to the ITEM a seller adds to a listing. Amazon allows you to