Grocery Coupon Codes Does Anyone Know How Sale Codes On Grocery Store Receipts?

Does anyone know how Sale Codes on Grocery Store Receipts? - grocery coupon codes

I'm booking an award for the personal use of my coupons in the store.
Trying to time the performance of not a notebook and write all the articles that will save you normally buy, I decided to go through old receipts go in search of general merchandise buying and discovered that Target, Sam's, Wal Mart and Kroger have codes to identify which is in addition to the retail price or not.
I used Meijer recipes, where the normal list price with the selling price.
Can anyone help me with this?
Sam and revenue Walmart: 0, N, X, P and T (T think it is a posteriori)
Objective: FN, T
Kroger: P & T

If there are other missing and I can go, it would be useful.

Thanks in advance