Barcode Glossary

Barcoding terminology defined.  Click on the letters below to jump to that area of the glossary.

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The determination if any element width or inter-character gap width differs from its nominal width by an amount greater than the printing tolerance.

Automatic Identification Manufactures Organization (AIM)

An organization supported by manufacturers and vendors of automatic identification products.


The position and orientation of a symbol relative to the scanner.

American National Standards Institute (ANSI)

An NGO that develops voluntary barcode quality standards for the United States. This group is part of the International Standards Organization (ISO).


The opening on a scanner that provides the field of view.


The use a label, tag or ticket will serve once the bar code is applied. For example, pharmaceutical applications, Department of Defense applications, etc.


The character set and code set forth in the American National Standard Code for Information Interchange, ANSI X3.4-1977. Each ANCII character is encoded with 7 bits and utilized for information interchange between data processing systems, communication systems, and other associated equipment. The ASCII set has both control and printing characters.

Aspect Ratio

The ratio of the bar’s height to the symbol’s length.


The ability for one barcode reader to recognize different symbologies and interpret several different codes.

Automatic Identification (Auto ID)

Different processes that let machines identify objects independent of human intervention.  For example, voice recognition, barcodes, RFID, etc.

Average Background Reflectance

The average of the background reflectance from at least five different points on the sheet (in percentage form)

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The area surrounding a symbol including spaces and quiet zones.


The darker element of a printed barcode symbol


A series of vertical bars or a bar pattern that can encode numbers and letters( contingent on width and pattern). This format is easily read by a barcode reader and can store real-time data.

Barcode Character

A single group of bars and stripes that represents a specific quantity (usually 1) of letters,  numbers, punctuation marks, or other symbols. The barcode character is the smallest part of a symbol that holds data.

Barcode Density

The maximum number of characters that can be represented in a linear unit of measure, which is often written as characters per inch or CPI.

Bar Height/Length

The bar dimension perpendicular to the bar width. Scanning occurs 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.

Bar Width Reduction (BWR)

The amount by which the bar width is reduced to compensate for print gain or bar width growth.


When a barcode can be read when scanned in either direction.

Blemish Percent

What percent of the total measured bar height has spots or voids.  This can be caused by ink or toner blobs, or running out of ink or toner.

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Character Set

Available character to encode in a barcode. Not all barcode types encode the same kinds of characters.

Characters Per Inch (CPI)

A measurement of barcode density.

Charged Coupled Device (CCD)

A device that moves an electrical charge to an area that it can be converted. In barcode terminology, it refers to a type of barcode reader that utilizes light-emitting diodes (LEDs) rather than a laser.

Check Digit/Check Character

Character added to prevent undetected errors.


Occurs when there is more than one barcode in the field of view at the same time by placing an electronic mask over the barcode.


A barcode symbology that uses four bars and three spaces to represent the numbers 0 through 9 and a set of special characters.

Code 11

A linear symbology utilizing 11 characters: 0-9 and -.

Code 128

A linear alphanumeric symbology created to reduce the amount of space occupied by the bar code. Each character has one of three different meanings, depending on which of three different character sets are employed. This symbology is used in the identification of products for containers and pallets  in the retail market. It is the labeling standard for UCC/EAN 128.

Code 16K

A stacked symbology where each symbol has between two and sixteen rows or stacks. It contains 18 bars and 17 spaces and each row is separated by a module separator bar.

Code 39

 The most popular linear symbology, capable of encoding both numbers and letters. Code 39 is used for shipping container labels by the Automotive Industry.

Code 49

A multi-row, continuous, variable length symbology.

Code 93

The complementary version of Code 39, but permits labels to be approximately 30 percent shorter.


The ability of a reading system to join together data from numerous symbols to create a single message.

Continuous type bar codes

A barcode that has a high amount of characters and is more difficult to print than discrete barcodes. For example, UPC, Interleaved 2 of 5, GS1 128, Postnet, etc.


The difference in reflectance between the black (bars) and white (spaces) areas in a symbol.

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Data Matrix

A 2D symbology that allows for the highest density of data per module. The finder pattern consists of solid left and bottom sides which form an “L” pattern, and a horizontal and vertical clock track on opposite sides of the “L”. The clock track tells the number of modules in the matrix and is used to decode the grid on which the modules are placed. There is no version information encoded explicitly within the Data Matrix symbology; all the information about the symbol size, encoding and error correction is determined from the size of the matrix. The symbology has a high degree error correction capability and is utilized in part marking and tracking.


The electronic package that receives signals from the scanner, performs the algorithm to interpret the signals into meaningful data, and provides the interface to other devices. A device that translates digital signals through the process of scanning a barcode, decoding it using the appropriate algorithm, and transmitting the data to the computer.


Voids found in the bars or spots found in the spaces and quiet zones of a symbol. It is the ratio between the maximum element reflectance nonuniformity and symbol contrast.

Defects = ERNmax/SC

ERNmax=Maximum element reflectance non-uniformity

SC=Symbol Contrast

The grade is broken down as follows:






Depth of Field

The distance between the closest and farthest point at which a barcode can be read at a specified X dimension

Diffuse Reflection

The part of the reflected light that spreads out in all directions from the reflecting surface (in comparison to the light from the scanner or verifier that is reflected back to the scanner or verifier).

Discrete type barcodes

Its character density is lower than continuous type barcodes symbologies and is easier to print. For example, Code 39, Codabar Postbar, etc.

Dot Matrix Printing

A type of print technology that utilizes needles which are evenly spaced across a moveable horizontal shuttle that move back and forth as the paper advances.The bar code is printed by creating overlapping adjacent dots. The dot size on the matrix printer restricts the narrow element size and density of the bar code.

Dots Per Inch (DPI)

A measurement for thermal printhead resolution and laser print engines resolution.

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EAN (International Article Number/European Article Number)

The European version of the UPC (Universal Product Code) barcode used in retail food packaging internationally. There are two different types of EAN codes, EAN-8 and EAN-13. It is now known as International Article Number rather than European Article Number, but the initials EAN remain.


This linear symbology has 13 characters or symbols. It is similar to the UPC code in application but has the 13th character for a country code.


This linear symbology has a left-hand guard pattern, four odd parity digits, a center guard pattern, four even parity digits, and a right-hand guard pattern. In total, there are 8 symbols.

Edge Contrast Minimum (Ecmin)

The minimum difference in the reflectance value between any particular space (including quiet zones) and its adjoining bar within a barcode symbol. The difference must be 15% or greater across the barcode symbol.

Edge Determination

First determine the Global Threshold (GT) of the barcode: GT = Rmin + (SC/2). Once the Global Threshold is calculated, the elements of a barcode you can define the elements of a barcode as follows:

BAR: Any point on the Scan Reflectance Profile at or below the Global Threshold.

SPACE: Any point on the Scan Reflectance Profile above the Global Threshold.

If the number of elements for a barcode symbology are not valid, the symbol will get an “F” grade for Edge Determination.

Edge Error (Edge Roughness)

Irregularities in the average or nominal edge of a barcode element from printing. If this error is too large, the symbol might not read.


A singlular space or bar in a barcode symbol.

Element Reflectance Non-uniformity

The difference in reflectance between the highest peak (highest value) and lowest peak (lowest value) within an element, bar or space, of the barcode symbol. A reflectance value of zero would be an element that has a singular peak or valley.

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First read rate (FRR)

The percentage of successful reads the first time a barcode is scanned.

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Tthe space between the last black bar of a character and the first black bar of the next character in a discrete type barcode.

Global Threshold (GT)

Halfway between the highest recorded reflectance and the lowest recorded reflectance on a Scan Reflectance Profile.

Guard Bars
Provides a reference point for scanning, similar in function to start and stop characters.  They are located at both ends and center of a UPC and EAN symbol.

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Horizontal  barcode

The axis of the symbol from start to stop is parallel to the horizon, making the bars appear like a picket fence.

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In Spec

When a barcode was printed in total compliance with the symbology specification’s requirements for element widths and tolerances, edge roughness, element reflectivity, voids, uniformity, and spots.

Interleaved 2-of-5 (I-25)

Interleaved 2-of-5 is a linear symbology that is most often used for encoding large amounts of information in a small area. Characters are paired together using bars to represent the first character and spaces to represent the second. Interleaved 2-of-5 barcode applications are prevalent in the electronics and manufacturing areas.

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Japanese Article Number (JAN)

A 13-digit code consisting of the flag code ( 49 or 45), a 5-digit marker code, a 5-digit item code, and a 1-digit check digit. It is very common in Japan and is accepted all over the world besides the United States of America and Canada. An 8-digit JAN type, called short version is also available for small products in Japan. It contains 2-digit flag, 4-digit maker code, 1-digit item code and 1-digit checkdigit. This symbology follows EAN Standards.

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Ladder Orientation

A barcode symbol of  vertical orientation with horizontal bars and spaces.

Laser (Light Amplification by the Stimulated Emission of Radiation)

A focused light source employed in fixed moving beam and handheld scanners and barcode verifiers.

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Manufacturer’s ID

The 6-digit number utilized to identify uniquely a manufacturer or company selling products under its own name for a UPC Code. It is the first 6 digits of the 12-digit UPC.

Matrix Symbols

A 2D symbology that are square in shape and have a finder pattern that provides a reference for decoding. The type of finder pattern depends on the type of Matrix symbol.


Maxicode is mainly used by the United Parcel Service (UPS) for sorting and tracking packages. These 2D codes are in the shape of a square with a pattern of dots and a bulls eye in the center.


One thousandth of an inch (.001 inch), or .0254 millimeter. It is the narrowest nominal width unit of measure in barcodes.

Minimum Reflectance (Rmin)

The reflectance value of the darkest bar within a barcode symbol.  It must be less than or equal to half the reflectance of the lightest space.

Minimum Reflectance Difference (MRD)

The difference of reflection ratios of white/black bars. This determines if there an adequate difference between absorbed and reflected light.


Occurs when the data output of a reader is not the same as the data encoded in the barcode symbol.


How a scanner interprets wide elements in relationship to narrow elements, as represented in the Scan Reflectance Profile by reflectance values. Scanners interpret narrow spaces as being less reflective than wide spaces normally.

MOD = ECmin/SC.


ECmin=Edge Contrast Minimum

SC=Symbol Contrast

The grade are broken down as follows:







The narrowest nominal width unit of measure in a barcode.


A type of barcode symbology that is made up of 4 bars and 4 spaces, representing 0 through 9.

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Unit of measurement for wavelengths of light.


The exact intended value for a parameter.


An attempted scan that fails because of the absence of data caused by the lack of a code, by the failure of a scanner or by an operator error.

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Optical Throw

The smallest distance where scanner/reader can read a barcode.


The alignment of a barcode with respect to horizontal. There are two types of orientations for barcodes: horizontal and vertical.  A horizontal orientation that has vertical bars and spaces is also called a picket fence.  A vertical orientation that has horizontal bars and spaces is also called ladder orientation.

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Print Contrast Signal (PCS)

A measurement of the ratio of the reflectiveness between the bars and spaces of a symbol, in percentage form. PCS is calculated as:

PCS = (Rw – Rb) / Rw

Rw = reflectance of the white bar
Rb = reflectance of the black bar

The minimum value of the Print Contrast Signal (PCS) differs by the value of reflectance of the white bar (Rw)


A  barcode that can store thousands of characters in its multi-stacks. This type of symbology can be found on the driver’s licenses of some states or used to store patient healthcare information.

Picket Fence Orientation

A barcode symbol in the horizontal orientation with vertical bars and spaces.

Plessey Code

A modulated barcode that is commonly found in shelf marking in grocers and big box stores.

Postnet Code

A height modulated, numeric symbology that uses 5 bars and 4 spaces for each digit.  Developed by the U.S. Postal Service, each bar is of a different height to cater to their fast printing.

Print Quality

The measure of compliance of a barcode symbol to the requirements of reflectance, dimensional tolerance, spots, encodation, edge roughness, voids, PCS and quiet zone.

Product ID

The 5-digit number given by a manufacturer to every consumer unit in its product catalog for a UPC Code. The Product ID is different for every standard package of the same product.

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Quick Response Code (QR Code)

A type of 2D barcode originally designed in Japan that can encode binary, JIS, Kanji, and alphanumeric information.

Quiet Zone

Blank space surrounding the barcode. This area provides the scanning device time to adjust to the measurements of each barcode in the message.

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More than one scan line in 2 or more horizontal dimensions which permits the reading of barcodes in different spots.

Read rate

The ratio of the number of successful reads to the total number of attempts.


A device that automatically reads data, whether they are barcodes, alphanumeric characters, or electronically stored data, like in a smart card or in a magnetic stripe. Normally a reader has a scanner or reading head, a communications interface, and a decoder.


The amount of light which is reflected back from the white spaces of a barcode to the amount of light reflected under similar illumination conditions in ratio form.


Utilized by thermal transfer printers to produce visible marks on a label. This is done by heating a printhead, causing the ribbon to be burned on the label stock which generates a barcode or other image.

RSS (Reduced Space Symbology)

A barcode symbology family that is now called the GS1 DataBar

RSS Expanded

A barcode symbology that is now called Gs1 DataBar Expanded.

RSS Limited

A barcode symbology that is now called Gs1 DataBar Limited

RSS Stacked

A barcode symbology that is now called GS1 DataBar Stacked.

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Scan line

The beam of light that reads across the barcode to gather information.

Scan rate

Scanner speed, measured in scans per second.

Scan Reflectance Profile (SRP)

A map of the localized symbol reflectivity as a measuring aperture is scanned across the symbol along a specific path. The peaks of the profile illustrate the largest value of reflectance (the barcode’s spaces) and the valleys of the profile indicate the smallest value of reflectance (the bar code’s bars).


When a single printing defect will not cause a character to be transposed into another valid character.


The lighter element of a barcode in between the bars.


A smudge or blemish made by stain, printer ink, dirt or any other imperfection.

Stacked Code

A barcode that stacked upon itself and broken up into sections to make the code more compact. For example, PDF 417, Micro PDF 417, GS1 DataBar, etc.


A set of rules, directions, instructions, and specifications on how to use a barcode.

Start Character

The character to the left of the barcode that allows for bidirectionality. The start character is at the top in a vertical barcode.

Stop Character

 The character to the right of the barcode that allows for bidirectionality. The stop character is at the bottom in a vertical barcode.

Substitution error

When a barcode misreads because of another character being substituted for the correct character.


The surface where a barcode is printed. For example, tag, thermal paper, label, etc.


A scannable entity that contains start/stop characters, data characters, check characters and quiet characters.

Symbol Contrast: (SC)

The difference between the largest reflectance values (including quiet zones) and smallest reflectance values within a Scan Reflectance Profile.

SC = Rmax – Rmin.
SC=Symbol Contrast

Rmax=largest reflectance value

Rmin=smallest reflectance value

The grades are broken down as follows:

A (4.0)>=70%

B (3.0)>=55%




The language used in the barcode.  For example, QR Code, UPC, EAN, etc.

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Thermal Direct

A printing technique where certain dots are heated and cooled while being dragged on heat-sensitive paper. Where it is heated, the paper will turn dark.

Thermal Transfer

A printing technique similar to thermal direct printing, but a single-use ribbon and common paper are used to prevent the problems of changing colors or fading that occur in the thermal direct method.

Two-Dimensional Barcode (2D Barcode)

Rectangular codes which ‘stack’ information to allow for more information storage in a smaller amount of space than a linear, or 1D, barcode.

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Uniform Code Council  (UCC)

This is the former name of GS1 US, an association that manages the UPC and other retail standards.


Utilized for primary and secondary product identification. Primary identification can be: the Serial Shipping Container Code and the U.P.C. Shipping Container Code.

UPC Code

The standard bar code symbology for retail food packages in the United States of America. Since its inception, the UPC code has been modified by Europe for international identification of food packages in the form of International Article Number (EAN).


A type of UPC symbol that is the most commonly utilized in retail operations. It is a numeric, fixed ratio barcode with 12 characters.  A quiet zone with 9 times the X-dimension is required.

UPC-E (“Zero Suppressed” Symbol)

A type of  UPC symbol that has six digits of data, but it needs less area than a UPC-A symbol. It can be referred to as a “Zero Suppressed” Symbol due to the fact that a 10-digit UPC-A code can be reduced to a six digit UPC-E format by suppressing the zeros that are redundant.

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A device that determines if the symbol meets the standards or specifications of a particular symbology by measuring the spaces, bars, optical characteristics and quiet zones.

Vertical Bar Code

The axis of the symbol from start to stop is perpendicular to the horizon, making the bars appear like rungs in a ladder.


The highest point of reflectivity in the barcode image (in camera based systems).


The lowest point of reflectivity in the barcode label image (in camera based systems).


A space or white area in a black bar (indicating an imperfection).

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Wand/Wand Scanner

A handheld scanning device used read barcodes.


Designs and builds the world’s most accurate barcode verification systems for linear and 2D symbologies.
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The width of the narrow spaces in bars in a barcode symbol measured in mils (thousandths of an inch).

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