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How to Determine Barcode Symbology

A barcode is a type of machine-readable data system made up of vertical bars. It was a system introduced in the early 1970s. There are many different system of barcodes including International Standard Book Numbering (ISBN), which is used in books, and PostNet, which is used by the United States Postal Service for automated mail sorting. In the U.S. and Canada, the most widely used barcode system is the Universal Product Code (UPC) barcode. An UPC barcode is printed on nearly all retail products sold in the U.S. and Canada.

Instructions

- 1
  Identify the barcode's guard bars. The guard bars are the two symmetrical lines that appear at the very beginning, in the middle and at the very end of an UPS barcode. Guard bars indicate the start and stop points of each part of the barcode. The first guard bar indicates the start point of the manufacture's code. It also serves to show what the width of one unit is. The middle zone guard bar indicates the end point of the manufacturer's code and the beginning of the product code. The last guard bar indicates the end of the code.
- 2
  Verify the manufacturer's code. The manufacturer's code is always on the left side of the barcode. The numbers along the bottom of the barcode are the numerical representation of what the bars in the barcode encode. Every individual barcode number is comprised of seven bar units. A single unit black bar is the equivalent of "0." A single unit of white space is the equivalent of "1." For example, in barcode symbology, the number "1" looks like: black bar, black bar, white space, white space, black bar, black bar, white space (or 0011001). Refer to the Tips to see how all the numbers (0 through 9) are written in a barcode.
- 3
  Confirm the product code. The product code is always on the right side of the barcode. Right-side barcode symbols are inverted, or "mirror," images of left-side bar code symbols. For example, a bar symbol on the left side of a barcode is a white space symbol on the right side of the barcode. This inversion of left-side and right-side barcode symbols is what allows a barcode to be scanned from either direction and still be accurately read.
- 4
  Determine what manufacturer or product is assigned to a specific number by looking it up in a UPS barcode database.

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