The Coupon Illusion

Nolen James Felten

April 2017


Coupons are a silly concept.

It would be my pleasure to not break the law with my keyboard.

This document is for educational purposes.

Don't be stupid.

If I have to write "for educational purposes",

What is a Coupon?

This question has kept me up at night.

The word "Coupon" is from Old French, and is a noun.

Definition: "Voucher entitling the holder to a discount for a particular product."

What is a Coupon, really?

In 1887, Coca-Cola used paper tickets, just paper.

Some fun facts about the history of coupons:

How does a piece of paper become a "Coupon"?

Coupons become commonplace for many retailers. Too common!
To improve efficiency and accuracy, barcode symbols are included on the face of the coupon.
As barcoding technology has evolved, so has the use of barcodes on coupons.

About The UPC Barcode

Wallace Flint was the first person to suggest an automated checkout system in 1932.
His system was economically unfeasible.
40 years later, as Vice President of the National Association of Food Chains, supported the efforts which led to the Uniform Product Code (UPC).

Norman Woodland and Bernard Silver are most often credited as having originally invented the barcode on October 20, 1949 by filing patent application serial number 122,416.
Though Norman Woodland and Bernard Silver pioneered the concept of barcodes, it was not until 1974 that the first UPC barcode was actually used in a supermarket.

IBM Engineer George Joseph Laurer developed the UPC.

Before joining IBM, he received the B.S. in electrical engineering from the University of Maryland in 1951. He came to the University after having served in World War II and attending a technical school to learn radio and TV repair.George Laurer is the holder of 25 patents. He is also the author of 20 published Technical Disclosure Bulletins.

"The Characteristics and Decodability of the Universal Product Code" - IBM Systems Journal 14(1): 16-34 (1975), By David Savir and George J. Laurer:

UPC Barcodes were deployed to speed up the checkout process. Thats it.

On June 26, 1974 at 8:01am, shopper Clyde Dawson was the first customer to buy an item that used a barcode. Juicy Fruit Gum. At "Marsh Supermarket" in Troy, Ohio.
Sharon Buchanan was the first cashier to scan a UPC barcode.
The register rang up 67 cents.

About The GS1-128 Barcode

Formerly known as UCC/EAN-128, the GS1-128 barcodes is used in conjunction with UPCs on many coupons.

How are Barcodes Generated?

Each UPC-A barcode consists of a scannable strip of black bars and white spaces above a sequence of 12 numeric digits.

Encoding table for UPC-A barcode pattern SLLLLLLMRRRRRRE
(left numerical digit)
(right numerical digit)
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
UPC-A Q.svg UPC-A S.svg UPC-A L0.svg UPC-A L1.svg UPC-A L2.svg UPC-A L3.svg UPC-A L4.svg UPC-A L5.svg UPC-A L6.svg UPC-A L7.svg UPC-A L8.svg UPC-A L9.svg UPC-A M.svg UPC-A R0.svg UPC-A R1.svg UPC-A R2.svg UPC-A R3.svg UPC-A R4.svg UPC-A R5.svg UPC-A R6.svg UPC-A R7.svg UPC-A R8.svg UPC-A R9.svg UPC-A E.svg UPC-A Q.svg

No letters or characters may appear on a UPC-A.
There is a one-to-one correspondence between 12-digit number and strip of black bars and white spaces.
There is only one way to represent each 12-digit number visually, and there is only one way to represent each strip of bars and white spaces numerically.




All Coupon UPC's provide three bits of info to the Poinr Of Sale machine:
"Who" - What manufacturer/company.
"Which" - Which product.
"How Much"- How much of a discount to give.

Identifier/Prefix This identifies the purpose of a UPC. 5 means it is a Coupon. When 9 is used, it means the coupon cannot be doubled or tripled. 0, 1, 6, 7, and 8 are used for products.
Manufacturer ID Code Number assigned to the manufacturer, truncated to 5 digits. Some large manufacturers may have more than one code, but they are not interchangeable, so you must be sure the code you have is the one used on the product you are making a coupon for. You can get this from the product UPC.
Family Code These 3 digits specify the product, or the range of products, by the manufacturer to which the coupon applies.
You may be able to get this from the product UPC (I'm making no guarantees), when that does work, it limits the coupon to working only with that exact product, that exact size, that exact variety.
It won't work with any other flavor/variety!
000 will work for any item by that manufacturer.
992 Bypass Code will allow a coupon to work for any item, any manufacturer.
Value Code 2 digit code that controls type of discount the coupon gives.
More on that, in a moment.
Checksum Specially calculated digit that the scanner reads to verify that it scanned the rest of the barcode correctly. The actual formula can be found on the Wikipedia article about UPCs.