Glossary of Barcode Terms


Glossary of Barcode Terms

A bar code verification term. The determination of whether any element width, or intercharacter gap width, differs from its nominal width by more than the printing tolerance.


The character set described in the American National Standard Code for Information Interchange. ASCII is used for information interchange between data processing systems, communications systems, and associated equipment.

Aspect Ratio

A bar code verification term. In a bar code symbol, the ratio of bar code symbol height to symbol length.

Asynchronous Communication

Also referred to as start/stop transmission. Every character transmitted has special bits attached, telling the receiving device when the data begins and ends. Data is transmitted independently with no associated clock. See also Synchronous communication.


The ability of bar code scanning and decoding equipment to recognize more than one symbology.

Average Background Reflectance

A bar code verification term. Expressed as a percent. See Reflectance.


The white spaces and quiet zones surrounding a printed bar code.

Bar Code

A technology that uses white spaces and black bars to represent encoded information. This encoded information can then be read with an optical device that converts the bars and spaces into an electrical signal, which is then decoded into the original characters.

Bar Code Character

A single group of bars and spaces that represents a specific individual number, letter, punctuation mark, or other symbol. This is the smallest subset of a bar code symbol that contains data.

Bar Code Reader

A device (light pen, laser gun, fixed scanner, etc.) used to read a bar code field.


The darker element of a printed bar code field.

Bar Width

The thickness of an individual bar measured from edge to edge of the same bar.


A bar code symbol capable of being read successfully if scanned in either direction.


Binary Synchronous Communication. Protocol supported by the AS/400 for communicating with other AS/400, IBM mainframe, System/36, and System/38 systems.

Black Mark

Sensor mark usually printed on the reverse (non-printing) side of tag stock, or on the liner (backing paper) of label stock.


Microsoft Windows bitmap graphics file format.

Butt Cut

Form of label stock used in continuous operations. Butt cut stock usually yields an additional 10% more individual labels than die cut stock.


Charge Coupled Device. Type of bar code scanner that uses LEDs (not lasers) to flood the bar code with light.

Character Set

Characters available for encodation in a particular bar code type. Not all bar code types can encode the entire ASCII character set.

Computer Integrated Manufacturing

Factory automation term where information is shared between computer aided design programs, materials resource planning (MRP) programs, and machine tools on the shop floor. Bar code data collection is an important part of a successful CIM implementation.

Clear Area

See Quiet Zone.


A numeric-only bar code type, in which each character is composed of seven elements: four bars and three spaces. CODABAR is currently used in a variety of applications such as libraries, medicine, and overnight package delivery. Also known as USD-4 code, NW-7, and 2 of 7 code, it was originally developed for retail price-labeling use.

Code 39

A full alphanumeric bar code type composed of five bars, four spaces, and an intercharacter gap for each character. Code 39 is the standard for many industries, including adoption by the U.S. Department of Defense for its LOGMARS specification. Also known as USD-3 code and 3 of 9 code, it is one of three symbologies identified in the ANSI standard MH10.8M-1983.

Code 49

An extremely compact, multi-row, continuous variable bar code type capable of encoding the full 128 ASCII character set. It is ideally suited to applications where large amounts of data are required in a small space. The code consists of 2 to 8 rows. A row consists of a leading quiet zone, 4 symbol characters encoding 8 code characters, a stop pattern, and a trailing quiet zone. Rows are separated by a one module high separator bar. Each symbol character encodes two characters.

Code 128

A high density, variable length, full alphanumeric bar code type capable of encoding all 128 ASCII characters. It was designed for complex encoded product identification and is the basis of the UCC-128 marking specification. Code 128 has three subsets of characters. There are 106 printing characters in each set. Therefore, each character can have three different meanings, depending on the character subset used. Each Code 128 character consists of six elements — three bars and three spaces.


Characters Per Inch. A common measurement for bar code density.


Also called a knife. An integrated mechanism used to cut individual tickets from a roll of tag supply.

Data Identifier

A compliance marking term. Message prefixes in a bar code that define the general category or intended use of the data that follows.


Distribution Center. When goods are shipped to a distribution center, the container marking specifications are usually different from those required when shipping directly to a store.


Data Communications Equipment. Hardware interface standard for modems, protocol converters, and other communications equipment. To interface DCE devices with DTE (Data Terminal Equipment) devices such as terminals or PCs, a straight through serial cable is required. See also DTE.


As part of a bar code reading system, the electronics that process the signals from the scanner, interpret the signals into meaningful data, and control the interface to other devices.

Depth of Field

The distance between the maximum and minimum surface in which a scanner is capable of reading bar codes of a specified X dimension.


A compliance marking term. See Data Identifier.

Die Cut

Type of label supply used in on demand applications. See also butt cut.

Diffuse Reflection

A bar code verification term. The component of reflected light that emanates in all directions from the reflecting surface (as opposed to the focused light of the scanner laser reflected back to the scanner).

Dot Matrix

A system of impact printing where individual dots are printed by tiny wires striking the supply through an inked ribbon.


Dots Per Inch. Used in comparing relative printing resolution of thermal printheads and laser print engines.


Direct Store Delivery. When goods are shipped directly to a store, the container marking specifications are usually different from those required when shipping to a distribution center.


Data Terminal Equipment. Hardware interface standard for display stations, personal computers, printers and other non-communications equipment. To interface a DTE printer with a DTE device such as a PC or a display station, a null-modem serial cable is required. See also DCE.


European Article Numbering system. The international standard bar code for retail food packages. The EAN-13 bar code type has 12 data characters, one more data character than the UPC-A code. An EAN-13 symbol contains the same number of bars as the UPC-A but encodes a 13th digit into a parity pattern of the left-hand six digits. This 13th digit, in combination with the 12th digit, represents a country code. The JAN-13 (Japanese Article Numbering system) is a special application of EAN-13.


Extended Binary Coded Decimal Interchange Code. Developed by IBM, it is the character set used by the IBM AS/400.


Electronic data interchange. Intercompany, computer-to-computer business transactions.


The international standard that supports EDI transactions across national boundaries.


A single bar or space in a bar code.


Federation of Automated Coding Technologies. Because of the large number of groups that have been independently developing bar code standards, FACT was formed to foster interindustry communications and coordination. An “association of associations,” FACT maintains a database of specifications and data identifiers.

First Read Rate

A bar code verification term. The ratio of the number of successful reads to the number of attempts. Commonly expressed as a percentage. Abbreviated as FRR.

Fixed Beam Scanner

A visible light or lasFixed beam scannerer scanner that requires a more exact positioning of a bar code than a moving beam scanner.


First Read Rate. See First Read Rate

Function Code

Function (FNC) codes define instructions for a bar code reader decoding Code 128 bar codes. FNC 1, for example, is a required component of the UCC-128 specification. FNC 2 tells the reader to store the data read and transmit it with the next symbol. FNC 3 is reserved for code reader intializing and other reader functions. FNC 4 is reserved for future use.

Guard Bars

The bars that are at both ends and center of a UPC and EAN bar code type. They provide reference points for reading, serving a function similar to start/stop codes.

HeNe Laser

A helium neon laser commonly used in bar code scanners.

Horizontal Barcode

A bar code type presented in such a manner that its overall length dimension is parallel to the horizon. The bars are presented in an array which looks like a picket fence.


Infrared laser diode. Used in some hand laser scanners to project a light beam.


The band of light wavelengths too long to be seen by the human eye. Used in access control and security applications where bar code fields must not be visible by human eye — only to an infrared scanner.

Interleaved 2 of 5

A high density, self-checking, continuous numeric bar code type in which each character is composed of five elements: five bars or five spaces. Of the five elements, two are wide and three are narrow. The bar code is formed by interleaving characters formed with all spaces into characters formed with all bars. Total number of digits must be even.

Label Gap

The space between adjacent labels on continuous form, die cut supply.


A bar code field printed in a rotation perpendicular to the horizon so that the individual bars appear as rungs on a ladder. Also referred to as a vertical bar code.


Light Amplification by the Stimulated Emission of Radiation. A focused light source (as opposed to LEDs used in wands and CCD readers) used in fixed, moving beam, and handheld scanners.


Light-emitting diode. The light source often used in light pens.

Light Pen

Also known as a wand. A scanning device which is used as a hand held bar code reader. Requires direct contact with the printed bar code field.


A compliance marking term. Logistics of Marking and Reading symbols. A Department of Defense marking specification.


One one-thousandth of an inch (0.001″). Unit of measurement used in bar code specifications.


A condition which occurs when the data output of a reader/decoder does not agree with the data encoded in the bar code field.


The width of the narrow bars in a bar code.

Moving Beam Scanner

A device where scanning is achieved by mechanically moving a light beam through the bars of a bar code field.


A bar code verification term. Unit of measure used to define the wavelength of light.

Net Data Density

A bar code verification term. The net data density of a linear bar code symbol is determined by dividing the number of characters in the symbol by the overall symbol length, measured from the leading edge of the start code to the trailing edge.


A bar code verification term. The exact (or ideal) intended value for a specified parameter. Tolerances are specified as positive and negative deviations from this value.


Optical Character Recognition. Technology for machine reading of human readable text.

On Demand

A printing mode where one label at a time is printed. The label is presented to the operator, separated from the backing paper. When the label is taken from the printer, the next label is printed and presented. Also known as Demand mode.


A bar code verification term. 1).The optical property of a substrate material that measures the show through from the back side or the next sheet. 2).The ratio of the reflectance with a black backing to the reflectance with a white backing. 3).Ink opacity is the property of an ink that prevents the substrate from showing through.

Optical Throw

The minimum distance a bar code can be away from a scanner and still be read.


Two possible bar code field orientations are horizontal with vertical bars and spaces (picket fence) and vertical with horizontal bars and spaces (ladder).


The bars and spaces representing the start, stop, function codes and check characters required by some symbologies. These increase the length of the bar code but do not affect the message content.


A bar code verification term. Print contrast signal. A measurement of the ratio of the reflectivity between the bars and spaces of a bar code field, commonly expressed in percent.


ZSoft Paintbrush bitmap graphics file format.

Picket Fence

A bar code type whose length is printed horizontally so that the bars are presented in an array which looks like a picket fence.


Price Look-Up. In a retail POS (Point Of Sale) system, the UPC bar code field is a key field in a price file that when scanned, retrieves a price for the encoded item.

Postnet Code

A bar code 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.

Print Quality

A bar code verification term. The measure of compliance of a bar code symbol to the requirements of dimensional tolerance, edge roughness, spots, voids, reflectance, PCS, quiet zone, and encodation.


Quick Response. A retail industry initiative to improve inventory turnaround through the use of EDI, bar code scanning, and the sharing of merchandise movement data with vendors.

Quiet Zone

A clear space, containing no machine readable marks, which precedes the start character of a bar code field and follows the stop characters. Sometimes called the “clear area.”

Read Rate

A bar code verification term. The ratio of the number of successful reads to the total number of attempts.


A bar code verification term. The ratio of the amount of light which is reflected back from the white spaces of a bar code during scanning to the amount of light reflected under similar illumination conditions.


The narrowest element dimension which can be recognized by a particular scanning device or printed with a particular device or method.

RF (Radio Frequency) Network

A technology that connects devices using electromagnetic waves instead of physical cabling.


A plastic tape with several layers of material, one of which is thermal wax, that when melted, produces the visible marks on the labels installed on a thermal transfer printer.


A common communication interface standard that permits DTEs and DCEs to connect successfully.


An electro/optical device that converts the bars and spaces of a bar code field into electrical signals.


Synchronous data link control. Protocol supported by the AS/400 for communicating with other AS/400, IBM mainframe, System/36, and System/38 systems.


A bar code verification term. Substitution error rate. The rate of occurrence of incorrect characters.

Show Through

A bar code verification term. Generally undesirable property of a supply that permits underlying markings to be seen.


Stock Keeping Units. In a distribution/retail environment, a generic term for item number.


System Network Architecture. Enterprise communications standard developed by IBM for linking different systems running IBM operating systems such as OS/400 (AS/400), OS/2 (PC), AIX (RS/6000), etc.

Space Width

A bar code verification term. The thickness of a space measured from the edge closest to the symbol start character to the trailing edge of the same space.

Spectral Response

A bar code verification term. The variation in sensitivity of a test surface to light of different wavelengths.

Stacked Code

Maxicode, 16K and Code 49 are examples where a long bar code field is broken into sections and “stacked” one upon the other, resulting in codes that are extremely compact.


An optional electromechanical accessory that is invaluable for unattended, organized, printing and cutting of multiple batches of tags.


A compliance marking term. A set of rules, specifications, instructions and directions to use a bar code or other automatic identification system. Usually issued by a trade organization.

Start-stop Character

A special bar code character that provides the scanner with start and stop reading instructions as well as scanning direction indicator.


The surface on which a bar code field is printed. Can be a label, tag, or paper supply.


See substrate.


A combination of bar code characters, including start/stop characters, quiet zones, data characters, and check characters required by a particular symbology, which form a complete, scannable entity.

Symbol Length

The distance between the outside edges of the quiet zones on the two ends of a bar code field.


Bar code type.

Synchronous Communication

Transmission of data which does not use special control bits, but requires a master clock signal for coordination between the devices. The clock may be a separate signal, or it may be part of the data.

Time and Attendance

An application using bar code employee badges and bar code slot reading terminals to enter employee start/stop data.

Thermal Direct

A printing method where dots are selectively heated and cooled and dragged upon heat-sensitive paper. The paper turns dark in the heated areas.

Thermal Transfer

A printing method like thermal direct except a onetime ribbon is used and common paper is used as a supply. This eliminates the problems of fading or changing color inherent in thermal direct printing.


Universal Product Code. The standard bar code type for retail products in the United States. See also UPC-A and UPC-E.


A fixed length, numeric, continuous bar code type used primarily in the retail industry for labeling packages. The UPC-A symbol encodes a number system character, 10 digits of data, and a Mod 10 check digit for error correction.


A UPC symbol encoding six digits of data in an arrangement that occupies less area than a UPC-A symbol. The UPC-E bar code type is a shortened version of the UPC-A bar code type in which zeroes are suppressed, resulting in codes that require less printing space. Used for labeling small items.


A compliance marking term. Uniform Product Carton Code, a standard administered by the UCC.


A device that makes measurements of the bars, spaces, quiet zones and optical characteristics of a bar code field to determine if the code meets the requirements of a specification or standard.

Vertical Bar Code

A bar code field printed in a rotation perpendicular to the horizon so that the individual bars appear as rungs on a ladder.

Visible Laser Diode

Used in some hand laser scanners to project a beam of light visible to the human eye, simplifying the scanning process.


A bar code verification term. An undesirable absence of ink in a bar.


See Light pen.


A device that plugs in between a keyboard and a terminal or PC. Allows data to be entered either by the keyboard or an attached scanner.


A compliance marking term. Warehouse Information Network Standard. Defines EDI transaction types for the warehouse industries.


Work-In-Progress/Process. An application using bar code totes and bar code scanners to track lots through a manufacturing operation.


An AS/400 program that serves as a link between an output queue and a printer. Normally the writer is started automatically at AS/400 IPL time.


The width of the narrow bars and spaces in a bar code type; usually measured in mils.

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