Universal Product Code

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The Universal Product Code (UPC) is one of a wide variety of bar code languages called symbologies. The UPC was the original barcode widely used in the United States and Canada for items in stores.

[edit] History

Wallace Flint proposed an automated checkout system in 1932 using punch cards. [1] Joseph Woodland patented a bull's-eye style code in 1952 and the first commercial use of barcodes was in 1966. [2]

In 1970 Logicon Inc. created the Universal Grocery Products Identification Code (UGPIC). In 1970 it was used by Monarch Marking in the United States and Plessey Telecommunications in the United Kingdom. [3]

A group of grocery industry trade associations formed the Uniform Grocery Product Code Council which with consulting firm McKinsey & Company defined the predecessor to the Uniform Product Code. In 1973 George J. Laurer developed the Universal Product Code.[4]

The first item to be placed under a UPC scanner in a retail store was a 10-pack of Wrigley's Chewing Gum at a Marsh Supermarket in Troy, Ohio, on June 26, 1974.^[1]

[edit] Current code

In the UPC-A barcode, each digit is represented by a seven-bit sequence, encoded by a series of alternating bars and spaces. Guard bars, shown in green, separate the two groups of six digits.

The UPC encodes twelve decimal digits as SLLLLLLMRRRRRRE, where S (start) and E (end) are the bit pattern 101, M (middle) is the bit pattern 01010 (called guard bars), and each L (left) and R (right) are digits, each one represented by a seven-bit code. This is a total of 95 bits. The bit pattern for each numeral is designed to be as little like the others as possible, and to have no more than four 1s or 0s in order. Both are for reliability in scanning.

The UPC is only numerals, with no letters or other characters. The first L digit is the U.P.C. Prefix. The last digit R is a check digit, so that errors in scanning or manual entry can be detected.

[edit] U.P.C. Prefixes

• 0, 1, 6, 7, 8, or 9 for most products
• 2 reserved for local use (store/warehouse), for items sold by variable weight. Variable-weight items, such as meats and fresh fruits and vegetables, are assigned a UPC by the store if they are packaged there. In this case, the LLLLL is the item number, and the _RRRR is either the weight or the price, with the first R determining which.
• 3 drugs by National Drug Code number. Pharmaceuticals in the U.S. have the remainder of the UPC as their National Drug Code (NDC) number; though usually only over-the-counter drugs are scanned at point-of-sale, NDC-based UPCs are used on prescription drug packages as well for inventory purposes.
• 4 reserved for local use (store/warehouse), often for loyalty cards
• 5 coupons, though many stores ignore this and use others. Likewise, coupons are supposed to have the coupon code in LLLLL, the amount to be taken off in _RRRR, and whether that amount is a percent or a literal amount encoded in the first R.

By prefixing these with a 0, they become EAN-13 rather than UPC-A. This does not change the check digit. All point-of-sale systems can now understand both equally.

[edit] Check Digit Calculation

In the UPC-A system, the check digit is calculated as follows:

1. Add the digits in the odd-numbered positions (first, third, fifth, etc.) together and multiply by three.
2. Add the digits in the even-numbered positions (second, fourth, sixth, etc.) to the result.
3. Subtract the result modulo 10 from ten. The answer modulo 10 is the check digit.

For instance, a UPC-A barcode (In this case, a UPC for a box of tissues) "03600029145X" where X is the check digit, X can be calculated by adding the odd-numbered digits (0+6+0+2+1+5 = 14), multiplying by three (14 × 3 = 42), adding the even-numbered digits (42+3+0+0+9+4 = 58), calculating modulo 10 (58 mod 10 = 8), subtracting from ten (10 - 8 = 2) and making modulo 10 (2 mod 10 = 2). The check digit is thus 2.

[edit] Representation

In the barcode, each number is represented by two bar and space configurations. One configuration is used in the "L" digits, while another is used in the "R" digits. This is done so that the barcode can be scanned forwards or backwards, and the scanner can determine from which direction the code is being scanned so that it can be registered correctly. If it were not for this, products could easily be registered incorrectly.

Each digit in UPC-A has two forms. In EAN there are two additional forms so that each digit can be encoded with even or odd parity. For instance, the number 6 can be encoded as:

• 0101111 (In the left half of a UPC-A barcode, or odd parity in the left half of an EAN barcode)
• 1010000 (In the right half of a UPC-A barcode, or odd parity in the right half of an EAN barcode)
• 0000101 (In even parity in the left half of an EAN barcode)
• 1111010 (In even parity in the right half of an EAN barcode)

The first and second forms are the one's complement of each other, as are the third and fourth.

The (L) codes for the ten digits are:

• 0: 0001101
• 1: 0011001
• 2: 0010011
• 3: 0111101
• 4: 0100011
• 5: 0110001
• 6: 0101111
• 7: 0111011
• 8: 0110111
• 9: 0001011

The (R) codes are simply the one's complement of the (L) codes.

The (R) codes:

• 0: 1110010
• 1: 1100110
• 2: 1101100
• 3: 1000010
• 4: 1011100
• 5: 1001110
• 6: 1010000
• 7: 1000100
• 8: 1001000
• 9: 1110100

Company Prefixes are assigned by a GS1 Member Organization, which is now using longer company codes (with shorter item codes) for smaller companies.

If you want to read barcodes yourself and not need to count one, zero, zero, one..., or have to memorize those, there is an easier "code" to reading barcodes. The bars and spaces in barcodes have four different lengths, or values. A digit in a UPC barcode consists of two spaces and 2 bars, the lengths of the digit always equalling seven. The lengths can be called 1, 2, 3 and 4. 1 is the thinnest, 2 is twice as wide as 1, 3 is as wide as three 1 bars, and 4 is the widest, equal to four 1 bars, or two 2 bars.

(L) codes:
0 : 3-2-1-1
1 : 2-2-2-1
2 : 2-1-2-2
3 : 1-4-1-1
4 : 1-1-3-2
5 : 1-2-3-1
6 : 1-1-1-4
7 : 1-3-1-2
8 : 1-2-1-3
9 : 3-1-1-2

For example, let's say the first digit in a barcode, after the 1-1-1 start code, is one. You would see a space 2 long, a bar 2 long, a space 2 long, and a bar 1 long. After the first six digits, there are five 1's (space bar space bar space), this is to make sure the barcode ends in a bar, not a space. After that, the digits on the right start with a bar and end with a space, the inverse of the digits on the left. Then the ending 1-1-1 sequence, which is bar-space-bar again.

[edit] Expansion

EAN was developed as a superset of UPC, adding an extra digit to the beginning so that there would be plenty of numbers for the entire world. The prefix digit 0 has been reserved for UPC, and in fact the Uniform Code Council has mandated all retail systems be able to recognize both UPC and EAN by January 1, 2005. This means that products marked with an EAN will be accepted in the US and Canada in addition to those products already marked with a UPC. Any product marked with a UPC does not have to be remarked with an EAN. In addition, this also expands the numbers available for the U.S. and Canada by 40%, adding 10 to 13 to the 00 to 09 (0 to 9 in UPC) already in use.

[edit] Superstition

In Greece during the time when the Schengen treaty was a hot topic in the news, opponents of the treaty started a fear campaign that referenced the UPC code. Flyers were pasted around town in Athens describing how the Schengen treaty was a sign that the world was coming to an end, citing that everyone would wear the number 666 on their forehead in the form of a national ID barcode, and equating this assertion to biblical references in the Book of Revelation as a sign of the times. First, these flyers would explain that in "computer language", the number 6 was represented by two thin bars, and would point to an example of the R side number 6 in the UPC code. The flyers would go on to relate these to the two thin bars at the beginning, middle, and end of each barcode, and equate these to the number 666. ^[2]

[edit] External links

• I Need a U.P.C. For My Product(s)
• 25th Anniversary Review of U.P.C. Impact (pdf download)
• GS1 Check Digit Calculator
• George J. Laurer's personal web site — Extensive info from the inventor of the UPC barcode.
• The Barcode FAQ — Links to barcode related white papers.
• The Internet UPC Database
• How to Read 12 Digit UPC Barcodes - WikiHow

• UPC-A Encoding — Learn how it works, see how it converts to a barcode.
• UPC Wiki — A wiki product catalog of barcodes and retail goods.

[edit] References

1. ^ Alan Q. Morton (1994). "Packaging history: The emergence of the Uniform Product Code (UPC) in the United States". History and Technology 11 (1): 101.
2. ^ Quark, Strangeness, and Charm Electronic ID, microchipping, the mark of the beast - some possible explanations