1/27/2024 0 Comments Upc barcode![]() The last digit in the UPC serves as an error-correcting check digit to ensure the code has been read correctly. Every size, color and combo demands a unique identifier to obtain accurate pricing and an up-to-date inventory. If the first digit is a 3, the item is a pharmaceutical.įollowing the leftmost six-digit manufacturer code is the middle marker (1111, as space-bar-space-bar-space) followed by five digits identifying the product. If the first digit is a 2, then the item is something sold by weight, like meats, fruit or vegetables, and the last six digits reflect the weight or price per pound. For example, when the first digit is a 5, it signifies a coupon and ties the coupon to the purchase required for its use. The first digit can define the operation of the code. The first six digits generally denote the product manufacturer. Now that you know how the bars encode the numbers, let’s turn to what the twelve digits mean. ![]() The top is my idealized representation of the encoding and the bottom is taken from a photograph of the label: Taking a closer look at the first six digits of my water bottle’s UPC, I’ve superimposed the widths and corresponding decimal value for each group of seven units. If you did, the first digit would be 0001101, the number seven would be 0111011 and so on but there’s no need for that, because the bands of light and dark are far easier to read with a beam of light than a string of printed characters. You could recast the encoding in ones and zeroes, where a black bar is a one and a white bar a zero. Do you see it? Once more, left-to-right, a white band, three units wide, a dark band two units wide, then a single white band and a single dark band (3-2-1-1 encoding the decimal value zero). So, for the leading value “zero,” the number is encoded as seven consecutive units divided into bars of varying widths: a bar three units wide, then (denoted by the change in color from white to black or vice-versa), a bar two units wide, then one then one. To convey the decimal string 078742, the encoded sequence is 3211 1312 1213 1312 1132 2122 where each number in the encoding is the width of the bars or spaces. Numbers in a bar code are encoded by the width of the bar or space, from one to four units. ![]() The start and end markers are each encoded as bar-space-bar and the middle is always space-bar-space-bar-space. Each number is encoded as seven bars and spaces (12×7=84 bars and spaces) and an additional eleven bars and spaces denote start, middle and end of the UPC. The black and white stripes of a UPC are the ones and zeroes of binary encoding. Just a dozen numeric characters are encoded by the ninety-five stripes of a UPC-A barcode, but those digits are encoded so ingeniously as to make them error resistant and virtually tamperproof. A lawyer using barcoded documents was pretty hot stuff back in the day. Bar codes and their smarter Japanese cousins, QR Codes, are perhaps the most unvarnished example of binary encoding in our lives.īarcodes have an ancient tie to e-discovery as they were once used to Bates label hard copy documents, linking them to “objective coding” databases. All, that is, save the humble Universal Product Code, the bar code symbology on every packaged product we purchase from a 70-inch TV to a box of Pop Tarts. Where does the average person encounter binary data? Though we daily confront a deluge of digital information, it’s all slickly packaged to spare us the bare binary bones of modern information technology.
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