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Barcode Frequently Asked Questions
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Final all the answers to your questions about barcodes below! Do you have a question that is not listed below? Email us, and we'll research a response.

  1. What is a bar code?
  2. Are there different bar codes?
  3. Which bar code do I use?
  4. How do I get a bar code number for my product?
  5. What size do I make a bar code?
  6. How do I print a bar code?
  7. How do I know the bar code that I printed is good?
  8. Can inkjet be used for bar code applications?

Q. What is a bar code?

A. You've probably seen barcodes before: they are printed on nearly every item in a grocery store. These are either UPC or EAN linear barcodes. However, there are over 300 other different types of bar codes. The next most popular linear bar code is Code 39 (also called Code 3 of 9). Then, there are 2D bar codes (see the 2D Page for more information) that can store a large amount of information in a smaller space than linear bar codes.

Most linear bar codes are nothing more than "license plates" that identify an item. The numbers and/or letters stored in the bar code are unique identifiers that, when read, can be used by a computer to look up additional information about the item. The price and description of the item is generally not stored in the bar code. The data is read from the bar code, sent to a computer, and the computer looks up the price and description of the item from the computer's database.

Bar codes are read by either scanning a point of light across the symbol or capturing a video image of the symbol and measuring the lengths of white spaces and black bars. The lengths and positions of the spaces and bars are analyzed by a computer program and the data is extracted. The relative widths of both the bars and spaces code the data stored in the bar code. The bar code reader detects these relative widths and decodes the data from the bar code.

Bar codes can be printed using most computer printers. The simplest way to print a bar code with your computer printer is to use a bar code font. You install the font on your computer just like any other font, and you can switch to the bar code font the same way you switch to any standard font.

A company can also order labels preprinted with bar code from vendors that specialize in printing bar codes.

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Q. Are there different bar codes?

A. In a book published by Mr. Benjamin Nelson in 1997, he describes over 260 different bar codes symbol formats. Many of these symbols are rarely used currently because they have been superseded by better symbols.

There are three basic types of bar codes: linear, 2D, and composite. Linear bar code symbols are easily identified by their tall printed bars of varying widths. There are many linear symbols but the ones used most frequently are called UPC-A, UPC-E, EAN-8, EAN-13, Code 39, Code 128, and ITF (Interleaved 2-of-5).

Two-dimensional (2D) bar code symbols are broken into two major groups called Matrix symbologies and Stacked bar codes. Matrix symbologies look like a matrix of printed dots and stacked bar codes look like linear bar codes with very short bars stacked on top of each other.

Composite symbols are a category of bar codes that combine an interdependent linear and 2D symbol. See AIM's book called Understanding 2D Symbologies for a summary of the most common 2D and composite symbols.

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Q. Which bar code do I use?

A. If you are developing a closed system strictly to be used within your company, then the choice is yours. You need to analyze what your requirements are as far as type of data (numeric, alphanumeric) as well has how much space you have available to print the code. If space is not constrained, then the most likely code is Code 128. Many industries are standardizing on Code 128. If you have a space problem, then you may want to evaluate one of the matrix symbologies. In general, it will cost you more for scanning equipment capable of scanning a matrix symbol.

If you need a copy of a bar code specification that tells you what the bars and spaces mean and what they are capable of encoding, AIM sponsors the development and publishing of bar code specifications. A notable exception to this rule would be the symbol specification for U.P.C. symbols, which is available from GS1 (formerly, UCC).

If you need to comply with a customer's bar code application, then you must obtain a copy of the application specification and whatever bar code is required by the specification is what you need to use. Industry standards tell you what bar code to use, how to build the information inside it, what size to print the bar code, where to put the bar code on your package or container, and what the minimum quality level is for your bar code.

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Q. How do I get a bar code number for my product?

A. When someone asks this question, they are usually talking about the UPC or EAN symbol found on most retail products around the world. Specifically, they are asking how to obtain a UPC or EAN company identification number which they can encode into a UPC-A or EAN-12 bar code symbol on their products.

In the USA, a company can obtain a unique six digit company identification number by becoming a member of GS1-US (formerly the Uniform Code Council (UCC)). In the rest of the world, contact GS1 (formerly EAN International (EAN)).

You must apply for membership and you will be assigned a unique company identification number for use on all your products. Note: Take a look at the UPC/EAN page which explains how to apply for a UPC/EAN number and gives technical formation about UPC/EAN.

What you get is a unique company identification number which is a 6 or 7-digit number. This is the first part of the product UPC/EAN code. The remaining 6 digits are assigned by you (not GS1) for a specific product. Each number must be unique for a particular product and product size. If you have an 8 oz. size and a 12 oz. size, for example, you need to assign two unique numbers.

If you want to bar code a book, you use the International Standard Book Number (ISBN). Visit the ISBN website for information that describes the process. If you are bar coding a monthly publication, you use the the International Standard Serial Number (ISSN). Here is a link to a website that describes the process for magazines.

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Q. What size do I make a bar code?
A. For a closed system (where you control the scanning environment), the size of the bar code is entirely up to you. You will simply use whatever size you need it to be for your scanning equipment. More about bar code scanning.

If you are trying to comply with an industry specification, an application specification will define the size that is needed in order to be in compliance. Most application specifications are based on a particular scanning environment and call for a specific bar code symbology, size of the narrow element, and height of the code.

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Q. How do I print a bar code?

A. There are two major types of printing equipment used to print bar codes, traditional pressroom equipment and electronic printing equipment. For those who are printing the same bar code over and over within their packaging graphics, the traditional pressroom approach is widely used. For those who print many different bar codes everyday or who print bar codes with information that varies (e.g. shipping labels, apparel tags, or foodservice labels) electronic printers are used. In order to print your own labels and tags you need a printing system comprised of a printer capable of printing bar codes, software to design your bar codes, and labels, tags, and ribbons/toner. Helping you find companies to assist you put a printing system together is exactly what AIM is all about. The AIM Buyer's Guide provides you with premier bar code equipment and service providers. More about bar code printing.

Keep in mind that whatever technology you use, it is your responsibility as the printer of these bar codes to verify that they conform with industry specifications and will be readable with any scanner that can decode the symbology you have printed. You can only do this with a bar code verifier. More about bar code verification.

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Q. How do I know the bar code that I printed is good?

A. Many people take their bar code to a scanner to see if it will scan, but the only way to know for certain is by scanning the bar code with a ANSI-based verifier. The difference between using an ANSI-based verifier and a scanner to determine if the bar code is good is the scanner only assures you that what you have printed can be scanned by that particular scanner. With a verifier, you will know if the symbol you have printed is scannable by any scanner in the world capable of decoding the particular symbology you have printed.

For more background on bar code print quality, you may download (PDF format) the AIM Layman's Guide to ANSI Print Quality Guideline.

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Q. Can inkjet be used for bar code applications?

A. Yes. Inkjet technology is being successfully implemented for 'direct-to-carton' bar code of corrugated packaging and shipping containers. Inkjet is often used for other 'unit' or 'product' marking and automated identification applications. Since no ribbons or labels are needed with inkjet coding, cost per mark savings can be found with inkjet coding systems.

AIM would like to thank Trident - An ITW Company for providing the answer to the above question.

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