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Data Collection: Glossary of Terms
Alphanumeric - The character set that contains letters, numbers, and usually other characters such as punctuation marks.
ANSI - The American National Standards Institute, a nongovernmental organization responsible for the development of voluntary standards.
Aperture - The opening in an optical system that establishes the field of view.
ASCII - The character set and code described in American National Standard Code for Information Interchange, ANSI X3.4-1977. Each ASCII character is encoded with seven bits. The ASCII character set is used for information interchange among data processing systems, communication systems, and associated equipment. The ASCII set consists of both control and printing characters.
Aspect Ratio - In a barcode symbol, the ratio of bar height to symbol length.
Bar - The darker element of a printed barcode symbol.
Barcode - An automatic identification technology that encodes information into an array of adjacent varying width parallel rectangular bars and spaces.
Barcode Character - A single group of bars and spaces that represents a specific number (often one) of numbers, letters, punctuation marks, or other symbols. This is the smallest subset of a barcode symbol that contains data.
Barcode Density - The number of data characters that can be represented in a linear unit of measure. Barcode density is often expressed in characters per inch.
Barcode Label - A label that carries a barcode symbol and is suitable to be affixed to an article.
Barcode Reader - A device used to read a barcode symbol.
Bar Length - The bar dimension perpendicular to the bar width. Also called bar height. Scanning is performed in an axis perpendicular to the bar length.
Bar Width - The thickness of a bar measured from the edge closest to the symbol start character to the trailing edge of the same bar.
Bi-directional - A barcode symbol capable of being read successfully independent of scanning direction.
Check Character - A character included within a string of data whose value is used for the purpose of performing a mathematical check to ensure the accuracy of that data.
Check Digit - A check digit serves the same purpose as a check character, but it may assume numeric values only.
Concatenation - The ability of a reading system to join together the data from multiple symbols and interpret it as a single message.
Decoder - As part of a barcode reading system, the electronic package that receives the signals from the scanner, performs the algorithm to interpret the signals into meaningful data, and provides the interface to other devices.
Depth of Field - The distance between the maximum and minimum plane in which a code reader is capable of reading symbols of a specified X dimension.
EAN - European Article Numbering system, the international standard barcode for retail food packages.
Film Master - A photographic film representation of a specific barcode or OCR symbol from which a printing plate is produced.
First Read Rate - The ratio of the number of successful reads on the first scanning attempt to the number of attempts. Commonly expressed as a percentage. Abbreviated as FRR.
Font - A specific size and style of printer's type.
HIBCC - The Health Industry Business Communications Council.
Input Device - That portion of a barcode reading system that employs electro-optical techniques to determine the localized reflectivity of a symbol.
Intercharacter Gap - The space between two adjacent barcode characters in a discrete code - for example, the space between two characters in Code 39.
Interleaved Barcode - A barcode in which characters are paired together using bars to represent the first character and spaces to represent the second, e.g., Interleaved 2 of 5.
Laser Scanner - An optical barcode reading device using a low energy laser light beam as its source of illumination. More info here.
LED - Light emitting diode. A semiconductor that produces light at a wavelength determined by its chemical composition. The light source often used in light pens.
Light Pen - In a barcode system, a handheld scanning wand that is used as a contact barcode reader held in the hand. See Wand Scanner.
Mil - One one-thousandth of an inch (0.001").
Misread - A condition that occurs when the data output of a reader does not agree with the data encoded in the barcode symbol.
Module - The narrowest nominal width unit of measure in a barcode.
Barcode Solutions - A barcode systems integration company representing the world's best manufacturers of related equipment and supplies at the lowest prices anywhere.
Multidrop - A network topology in which multiple devices, each with a unique address, are connected to a common set of data communication lines.
Nominal - The exact (or ideal) intended value for a specified parameter. Tolerances are specified as positive and negative deviations from this value.
Numeric - A character set that includes only the numbers.
OCR-A - An abbreviation commonly applied to the character set contained in ANSI Standard X3.17-1981. A stylized font choice used for Traditional OCR printing.
OCR-B - An abbreviation commonly applied to the character set contained in ANSI Standard X3.49-1975. A stylized font choice used for Traditional OCR printing.
Orientation - The alignment of a barcode symbol with respect to horizontal. Two possible orientations are horizontal with vertical bars and spaces (picket fence) and vertical with horizontal bars and spaces (ladder).
PDF417 - 2-Dimensional barcode. More info here.
Port Concentrator - A piece of data communication equipment that allows several different connected devices to transmit data to or receive data from a single master communication port.
POS - Point of sale.
Postnet Code - A symbology used primarily by the U.S. Postal Service for mail sortation. All bars and spaces are the same width. ZIP Code information is encoded into the particular arrangement of tall and short bars. This is a ``height modulated" symbology.
Pre-Printed Symbol - A symbol that is printed in advance of application either on a label or on the article to be identified.
Print Quality - The measure of compliance of a barcode symbol to the requirements of dimensional tolerance, edge roughness, spots, voids, reflectance, PCS, quiet zone, and encodation.
Quiet Zone - A clear space, containing no dark marks, that precedes the start character of a barcode symbol and follows the stop characters. Sometimes called the ``clear area."
Reflectance - The ratio of the amount of light of a specified wavelength or series of wavelengths reflected from a test surface to the amount of light reflected from a barium oxide or magnesium oxide standard under similar illumination conditions.
Resolution - In a barcode system, the narrowest element dimension that can be distinguished by a particular reading device or printed with a particular device or method.
Scanner - An electronic device that electro-optically converts optical information into electrical signals.
Self-Checking - A symbology is termed self-checking if a single printing defect will not cause a character to be transposed into another valid character in the same symbology.
Space - The lighter element of a barcode usually formed by the background between bars.
Symbol - A combination of barcode characters (including start/stop characters, quiet zones, data characters, and check characters required by a particular symbology), that forms a complete, scannable entity.
Traditional OCR - The first form of two-dimensional OCR developed, using the stylized OCR-A and OCR-B fonts.
Uniform Container Symbol (UCS).
Uniform Code Council (UCC) - Previously the Uniform Product Code Council; the organization that administers the UPC and other retail standards.
Universal Product Code (UPC) - The standard barcode symbol for retail food packages in the United States.
UPC-A - A UPC symbol encoding a number system character, 10 digits of data, and a check digit.
UPC-E - A UPC symbol encoding six digits of data in an arrangement that occupies less area than a UPC-A symbol. Also called a ``zero-suppressed" symbol because a 10-digit UPC-A code can be compressed to a six-digit UPC-E format by suppressing redundant zeros.
Uniform Symbol Specification (USS) - The current series of symbology specifications published by AIM; they now include USS-Interleaved 2 of 5, USS-39, USS-93, USS-Codabar, USS-128, USS-49, and USS-16K.
Wand Scanner - A handheld scanning device used as a contact barcode or OCR reader.
X Dimension - The nominal width dimension of the narrow bars and spaces in a barcode symbol.
Barcode is a pattern of bars and spaces which represent numbers, letters or characters.
Code 39, for instance, has a unique pattern. Code 3 of 9, as it is sometimes
called, derives its name from the way in which the pattern is created. Each
character has nine elements (five bars and four spaces) and three of them are
Why Use Barcode?
Barcodes are accurate. They eliminate manual data entry errors. Research has shown that the error rate due to barcode misreads is less than one thousandth of one percent. Tests have shown that barcoded information had a throughput accuracy rate of 1 error in 10,000,000 characters. Compare that to keyboard entry error rates of 1 error in 100 characters.
Barcodes speed data entry. Even with a simple wand, a barcode can be scanned in a fraction of the time it takes to enter the information manually. CCD and laser scanners are also available for even faster data entry.
Barcodes can be produced easily and cheaply. Barcodes can be printed on most computer printers, for the cost of ink and paper. Even a low cost dot matrix printer can produce barcodes of adequate quality.
How Does a Scanner Work?
Scanners are the devices that read barcodes. A scanner shoots pulses of light. If it falls on a light area, a zero (0) is read. If it falls on a dark area, it reads a one (1). Scanning the barcode generates a string of zeros and ones. This pattern of zeros and ones represents the characters encoded. The scanner software, or firmware, translates or decodes the strings into characters.
The scanner must be able to shoot a straight line across the bars and spaces. The taller the bars the greater the angle and the greater the chances of getting a good reading.
The shorter the bars the less likely the scanner will be able to shoot a
straight line through the bars and spaces.
What Does the Barcode Represent?
No matter which barcode is used, the information encoded in the bars and spaces may be displayed above or below the bars. Since this is the aspect understandable to us, the characters are referred to as human readables. The bars and spaces are readable by machine.
UPC (A) is just one of several barcode symbologies. In the typical format, each of the elements of the barcode symbol represent predefined information.
The system digit and the manufacturer number are assigned by the Uniform Code Council, Inc. for UPC (Universal Product Code) in the United States and Canada. UPC is a subset of EAN (European Article Number), the international product code standard throughout the rest of the world.
The product identification number is assigned by the manufacturer. The check digit is used to check the data that is read.
These are, perhaps, the most commonly used barcodes. They can be found on almost all general merchandise.
To apply for a manufacturer identification number call or write:
The Uniform Code Council, Inc.
8163 Old Yankee Road, Suite J
Dayton Ohio 45458
Telephone: (513) 435-3870
If your company is located outside of the United States or Canada, to find the location of the local EAN agency contact:
International Article Numbering Association
Rue Royale 145
web site: http://www.ean.be/
Elements of Barcode
No matter which symbology you will be using, all barcode share elements that make up the symbol. These are the bars and spaces, the human readables, and the quiet zone. In addition, a symbology may be either Discrete or Continuous.
Bars and Spaces
The bars and spaces determine the pattern of the encoded data. Each symbology represents a different strategy behind the creation of these patterns such as: being as condense as possible, printing as easily as possible, being as easy to decipher as quickly as possible, etc.
Each barcode has slightly different quiet zone requirements. For example,
the quiet zone of Code 39 is ten times the width of the thinnest bar/space or
0.25 inches, whichever is greater.
The human-readable is the data represented by the bars and spaces printed as text for people to read. The actual data encoded here is 3*35353*2. The asterisks are not displayed as human-readables in this example.
The Quiet Zone
The quiet zone is the clear area (free from marks) before and after the bars and spaces. Having a quiet zone is as important to readability as the bars and spaces! Scanners need to establish values for the quiet zone before they can evaluate the bars and spaces. Reading the color and reflectance of the quiet zone establishes how the spaces will read and determines the difference between the spaces and the bars. Barcode cannot be read without a quiet zone.
Even though the quiet zone actually surrounds the code (the Bar/Space image), the clear area above and the below the Bar/Space image is not required for readability of most symbologies.
Discrete vs. Continuous barcode
Discrete symbologies consist of unique bar and space patterns for each character. Continuous codes cannot be separated into individual characters.
ITF is a continuous barcode. You cannot pull it apart into discrete, individual characters. Notice how the bars of the 3 and 5 are embedded in the bars of the 8 and 2.
Codabar is a discrete barcode. You can pull apart characters into discrete, individual units. The spaces between characters do not have critical dimensions.
The pattern of the number five is 310000102 where ć11 is a wide bar or space
and ć01 is a narrow bar or space.
What is a Check Digit?
A check digit is used to check that the data is read correctly. Different symbologies apply different formulas to the encoded numbers to yield a single digit. That digit is the check digit. That check digit is usually added to the end of the already encoded numbers.
The computer checks that the numbers were read correctly by comparing the check digit it calculates against the check digit it read.
For example: When encoding the ZIP code 311215-12352 into POSTNET, the check digit is the total of the numbers subtracted from the next higher multiple of ten.
In the POSTNET barcode the numbers to be encoded would be 311215123592. The barcode reader reads 311215123592. Reading a check digit of 392 and calculating a check digit of 392 from the other numbers it read, the barcode reader now is doubly certain that the numbers were correctly decoded.
Barcode technology is millions of times more accurate than typing when it comes to entering information into the computer. Check digits make the systems even more accurate. Tests have shown that operators may do 10,000,000 entries between errors when using check digits.
How Small Can I Make the Barcode?
How small the barcode can be becomes a function of how finely the printer can print and how fine of a barcode a reader can read.
Industry guidelines will strongly caution against undersizing barcodes. This is good advice. There may be times when you want barcode as small as possible, however, this is only true until it becomes less readable. You must then weigh the difficulties that may be encountered when reading the barcode against the advantages of having smaller barcode.
UPC, EAN and JAN codes should never be used below 80% magnification. Even then this should be done only when the printing techniques are controlled and of sufficient resolution to get the tolerances necessary.
UPC, EAN and JAN codes should never be used below 80% magnification.
All of your work should be verified, especially at lower (smaller) magnifications.
Readability vs scannabilty
Readability is the measurement of how well the symbol is interpreted. scannabilty is a measure of the ease with which the scanner can decipher the symbol. For example, if two symbols were equally readable, a tall symbol is considered more scannable than a short one because there is a greater chance that the scanner will see the taller symbol.
Likewise, two symbols that are equally scannable may differ in readability due to the narrowness of the symbols or the quality of the printing.
The specifications that affect the readability and scannabilty of a symbol are width, color, printer dpi, bar width reduction, reflectance, and contrast. Symbol height only affects scannabilty.
In relation to retail checkout counters, first-scan readability is the ideal.
In other words, the goal is for the scanner to be able to read the symbol the
first time it is scanned. It does no good to create barcode that causes the
checker to have to try over and over to read it. After a while the checker will
stop attempting to scan your products. Worse yet, your products may be pulled
from the shelves and returned to you if they don't scan easily. The goal is for
the scanner to be able to read the symbol the first time it is scanned.