A Swiss postal barcode encoding "RI 476 394 652 CH" in Code 128 (B & C)
Code 128 is a high-density linear barcode symbology defined in ISO/IEC 15417:2007.[1] It is used for alphanumeric or numeric-only barcodes. It can encode all 128 characters of ASCII and, by use of an extension symbol (FNC4), the Latin-1 characters defined in ISO/IEC 8859-1.[citation needed] It generally results in more compact barcodes compared to other methods like Code 39, especially when the texts contain mostly digits. Code 128 was developed by the Computer Identics Corporation in 1981.[2]
A GS1-128 barcode encoding GTIN, best before date and batch number
GS1-128 (formerly known as UCC/EAN-128) is a subset of Code 128 and is used extensively worldwide in shipping and packaging industries as a product identification code for the container and pallet levels in the supply chain.
Specification
Schematic of a barcode (Code 128B). 1:quiet zone, 2:Start Code B, 3:data, 4:checksum, 5:stop
A Code 128 barcode has seven sections:
Quiet zone
Start symbol
Encoded data
Check symbol (mandatory)
Stop symbol
Final bar (often considered part of the stop symbol)
Quiet zone
The check symbol is calculated from a weighted sum (modulo 103) of all the symbols.
Subtypes
Code 128 includes 108 symbols: 103 data symbols, 3 start symbols, and 2 stop symbols. Each symbol consists of three black bars and three white spaces of varying widths. All widths are multiples of a basic "module". Each bar and space is 1 to 4 modules wide, and the symbols are fixed width: the sum of the widths of the three black bars and three white bars is 11 modules.
The stop pattern is composed of two overlapped symbols and has four bars. The stop pattern permits bidirectional scanning. When the stop pattern is read left-to-right (the usual case), the stop symbol (followed by a 2-module bar) is recognized. When the stop pattern is read right-to-left, the reverse stop symbol (followed by a 2-module bar) is recognized. A scanner seeing the reverse stop symbol then knows it must skip the 2-module bar and read the rest of the barcode in reverse.
Despite its name, Code 128 does not have 128 distinct symbols, so it cannot represent 128 code points directly. To represent all 128 ASCII values, it shifts among three code sets (A, B, C). Together, code sets A and B cover all 128 ASCII characters. Code set C is used to efficiently encode digit strings. The initial subset is selected by using the appropriate start symbol. Within each code set, some of the 103 data code points are reserved for shifting to one of the other two code sets. The shifts are done using code points 98 and 99 in code sets A and B, 100 in code sets A and C and 101 in code sets B and C to switch between them):
128A (Code Set A)–ASCII characters 00 to 95 (0–9, A–Z and control codes), special characters, and FNC 1–4
128B (Code Set B)–ASCII characters 32 to 127 (0–9, A–Z, a–z), special characters, and FNC 1–4
128C (Code Set C)–00–99 (encodes two digits with a single code point) and FNC1
The minimum width of the quiet zone to the left and right of the Code 128 is 10x, where x is the minimum width of a module. It is mandatory at the left and right side of the barcode.
Start/stop and bar widths
Each symbol in the barcode is composed of three bars and three spaces. Each bar or space is 1, 2, 3 or 4 units wide, the sum of the widths of bars must be even (4, 6 or 8 units), the sum of the widths of the spaces must be odd (3, 5 or 7 units), and total 11 units per symbol. For instance, encoding the ASCII character "0" can be viewed as 10011101100, where a sequence of 1's is a bar and a sequence of 0's is a space. A single 1 would be the thinnest line in the bar code. Three 1's in sequence (111) indicates a bar three times as thick as a single 1 bar.
There are 108 possible 11-unit wide symbols, and the code uses all possible symbols. Two of the symbols are used for stop (end-of-barcode) indication, stop and reverse stop. The two stop symbols are special because they are always followed by a 2-unit bar, forming a 13-unit long stop pattern. Reading the stop pattern left to right is the stop symbol (followed by a 2-unit bar), and reading the stop pattern right to left is the reverse stop symbol (followed by a 2-unit bar).
Check digit calculation
The check digit is a weighted modulo-103 checksum. It is calculated by summing the start code 'value' to the products of each symbol's 'value' multiplied by its position's weight in the barcode string. The start symbol and first encoded symbol are in position 1. The sum of the products is then reduced modulo 103. The remainder is then converted back to one of the 103 non-delimiter symbols (following the instructions given below) and appended to the barcode, immediately before the stop symbol.
For example, in the following table, the code 128 variant A checksum value is calculated for the alphanumeric string PJJ123C:
Code
Value
Weight
Value × Weight
Start Code A
103
(1)
103
P
48
1
48
J
42
2
84
J
42
3
126
1
17
4
68
2
18
5
90
3
19
6
114
C
35
7
245
Sum
878
Remainder mod 103
54
So the value 54, which equals a V, is appended, then followed by the Stop code.
For the purpose of computing the check symbol, the shift and code-switch symbols are treated the same as any other symbol in the bar code.
Using FNC4 to encode high (160–255) characters
The special symbol FNC4 ("Function 4"), present only in code sets A and B, can be used to encode all the Latin-1 (ISO-8859-1) characters in a Code 128 barcode.[3]
When a single 'FNC4' is present in a string, the following symbol is read like ASCII, but the value is incremented by +128, thus taking the higher range of the ISO-8859-1 table. If the following symbol is a 'SHIFT', then a second symbol will be used to obtain the character.
If two consecutive 'FNC4' characters are used, all following data characters are extended ASCII characters until two further consecutive 'FNC4' characters are encountered or the end of the symbol is reached. If during this sequence of extended encodation a single 'FNC4' character is encountered it is used to revert to standard ASCII encodation for the next data character only. 'SHIFT' and character subset characters shall have their normal effect during such a sequence.[4]
From Code 128A you can reach Latin-1 special characters from 160 (hex A0, non breaking space) up to 223 (hex DF, ß) via FNC4. The lower case characters from 224 (hex E0, à) to 254 (hex FE, þ) are available by FNC4+SHIFT B. The characters ÷ (247, hex F7) and ÿ (255, hex FF) are not available.
The feature is not available for GS1-128.[5][6] Since the support of Code 128 Type B (and C) is not very common, it might be easier to use a QR Code instead for characters from the ISO-8859-1 code range.
Bar code widths
Code128 specifies a combination of 6 alternating bars and spaces (3 of each) for each symbol. Thus, each symbol begins with a bar and ends with a space. In barcode fonts, the final bar is generally combined with the stop symbol to make a wider stop pattern. The following table details the widths associated with each bar and space for each symbol. The width of each bar or space may be 1, 2, 3 or 4 units (modules). Using the example above, an 'A' would be depicted with the pattern 10100011000, or as widths 111323 in the tables below.
The widths value is derived by counting the length of each run of 1's then 0's in the pattern, starting from the left. There will always be 6 runs and the lengths of these 6 runs form the Widths value. For example, using the pattern 10100011000, the run lengths are 1 (digit 1), 1 (digit 0), 1 (digit 1), 3 (digit 0), 2 (digit 1), 3 (digit 0). Reporting just the lengths of each run gives 1, 1, 1, 3, 2, 3, thereby producing a widths value of 111323.
The "Code A", "Code B" and "Code C" symbols cause all following symbols to be interpreted according to the corresponding subcode (i.e. 128A, 128B or 128C). The "Shift" symbol switches a single following symbol's interpretation between subcodes A and B.
The encoded ASCII char depends on the actual used barcode-font. Especially the ASCII char of value 0 and of value 95 and above may be defined differently in the font that is installed.
The FNCx codes are used for special purposes. FNC1 at the beginning of a bar code indicates a GS1-128 bar code which begins with a 2- 3- or 4-digit application identifier assigned by the Uniform Code Council, which explains the following digits. For example, application identifier 421 indicates that an ISO 3166-1 numeric country code and ship-to postal code follows. Thus, the U.S. ZIP code for the White House would generally be printed as "(421) 840 20500", but would actually be coded as "[Start C] [FNC1] 42 18 40 20 50 [Code A] 16 [Check symbol 92] [Stop]"
FNC2 (message append) can appear anywhere within a barcode to indicate that the barcode reader should store the current string and prepend it to the string of the next barcode that's read. It is not used by GS1-128.
FNC3 (initialize) can appear anywhere within a barcode to instruct the barcode reader to initialize or reprogram itself according to the barcode string's instructions.
For the end user, Code 128 barcodes may be generated by either an outside application to create an image of the barcode, or by a font-based barcode solution. Either solution requires the use of an application or an application add in to calculate the check digit and create the barcode.
Barcode length optimization by Code 128 Type-C
Code set C uses one code symbol to represent two digits. Thus it may create shorter barcodes if the content consists of numbers only or if there are longer sequences of digits within the code.
However, when the string contains only a few digits or it's mixed with non-digit character, it does not always produce a more compact code than code sets A or B. Using code set C saves one symbol per two digits, but costs a mode-shift symbol to enter and exit the set. Thus, it is only worth using if there are enough consecutive digits. For example, encoding the string "X00Y" with code set A or B requires 7 code symbols ([Start B] 56 16 16 57 [checksum] [Stop]), while using code set C for the "X00Y" would result in a code 8 symbols long ([Start B] 56 [Code C] 00 [Code B] 57 [checksum] [Stop]).
Using code set C is only advantageous under the following conditions:
Location of digits
Number of consecutive digits
beginning of data
4+
end of data
4+
middle of data (surrounded by symbols from code set A or B)
6+
entire data
either 2 or 4+ (but not 3)
At the end of a string, delaying the transition to code set C until there are an even number of digits remaining avoids an extra symbol. Consider the string "...01234": a delayed switch produces ... 0 [Code C] 12 34 [checksum] [Stop] but an early switch produces ... [Code C] 01 23 [Code A] 4 [checksum] [Stop].[8]
For example, given the string "098x1234567y23", savings on barcode length using code set C are achieved only if it is applied to middle part of the string. For the beginning and ending part of the string, switching to code set C is not effective. As there are an odd number of digits in the middle of the string, the odd one must use a different code set, but it makes no difference whether this is the first or last; 16 symbols are required in either case: [Start B] 0 9 8 x 1 [Code C] 23 45 67 [Code B] y 2 3 [checksum] [Stop], or [Start B] 0 9 8 x [Code C] 12 34 56 [Code B] 7 y 2 3 [checksum] [Stop].
Optimizing the length of the resulting barcode is important when barcode readers are used which must detect the entire barcode image at once in order to read it, such as common laser scanners. The longer the barcode is, the greater distance of laser barcode reader from barcode image is needed, making reading difficult or impossible above some threshold lengths/distances.
The Universal Product Code is a barcode symbology that is used worldwide for tracking trade items in stores.
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or one-dimensional (1D), can be scanned by special optical scanners, called barcode readers, of which there are several types.
Code 39 is a variable length, discrete barcode symbology defined in ISO/IEC 16388:2007.
PDF417 is a stacked linear barcode format used in a variety of applications such as transport, identification cards, and inventory management. "PDF" stands for Portable Data File. The "417" signifies that each pattern in the code consists of 4 bars and spaces in a pattern that is 17 units (modules) long. The PDF417 symbology was invented by Dr. Ynjiun P. Wang at Symbol Technologies in 1991. It is defined in ISO 15438.
The Aztec Code is a matrix code invented by Andrew Longacre, Jr. and Robert Hussey in 1995. The code was published by AIM, Inc. in 1997. Although the Aztec Code was patented, that patent was officially made public domain. The Aztec Code is also published as ISO/IEC 24778:2008 standard. Named after the resemblance of the central finder pattern to an Aztec pyramid, Aztec Code has the potential to use less space than other matrix barcodes because it does not require a surrounding blank "quiet zone".
Code 93 is a barcode symbology designed in 1982 by Intermec to provide a higher density and data security enhancement to Code 39. It is an alphanumeric, variable length symbology. Code 93 is used primarily by Canada Post to encode supplementary delivery information. Every symbol includes two check characters.
Interleaved 2 of 5 (ITF) is a continuous two-width barcode symbology encoding digits. It is used commercially on 135 film, for ITF-14 barcodes, and on cartons of some products, while the products inside are labeled with UPC or EAN.
Telepen is a name of the barcode symbology designed to encode all 128 ASCII characters without using shift characters for code switching, and only using two different widths for both bars and spaces.. The symbology was devised by George Sims of SB Electronic Systems Ltd. Telepen was originally designed in the UK in 1972.
A Data Matrix is a two-dimensional code consisting of black and white "cells" or dots arranged in either a square or rectangular pattern, also known as a matrix. The information to be encoded can be text or numeric data. Usual data size is from a few bytes up to 1556 bytes. The length of the encoded data depends on the number of cells in the matrix. Error correction codes are often used to increase reliability: even if one or more cells are damaged so it is unreadable, the message can still be read. A Data Matrix symbol can store up to 2,335 alphanumeric characters.
The International Article Number is a standard describing a barcode symbology and numbering system used in global trade to identify a specific retail product type, in a specific packaging configuration, from a specific manufacturer. The standard has been subsumed in the Global Trade Item Number standard from the GS1 organization; the same numbers can be referred to as GTINs and can be encoded in other barcode symbologies, defined by GS1. EAN barcodes are used worldwide for lookup at retail point of sale, but can also be used as numbers for other purposes such as wholesale ordering or accounting. These barcodes only represent the digits 0–9, unlike some other barcode symbologies which can represent additional characters.
Codabar is a linear barcode symbology developed in 1972 by Pitney Bowes Corp. It and its variants are also known as Codeabar, Ames Code, NW-7, Monarch, Code 2 of 7, Rationalized Codabar, ANSI/AIM BC3-1995 or USD-4. Although Codabar has not been registered for United States federal trademark status, its hyphenated variant, Code-a-bar, is a registered trademark.
MSI is a barcode symbology developed by the MSI Data Corporation, based on the original Plessey Code symbology. It is a continuous symbology that is not self-checking. MSI is used primarily for inventory control, marking storage containers and shelves in warehouse environments.
RM4SCC is the name of the barcode character set based on the Royal Mail 4-State Bar Code symbology created by Royal Mail. The RM4SCC is used for the Royal Mail Cleanmail service. It enables UK postcodes as well as Delivery Point Suffixes (DPSs) to be easily read by a machine at high speed.
Industrial 2 of 5. is a variable length, discrete, two width symbology. Industrial 2 of 5 is a subset of two-out-of-five codes.
Codablock is a family of stacked 1D barcodes which was invented in Identcode Systeme GmbH in Germany in 1989 by Heinrich Oehlmann. Codablock barcodes are based on stacked Code 39 and Code 128 symbologies and have some advantages of 2D barcodes.
Matrix 2 of 5 is a variable length, discrete, two width symbology. Matrix 2 of 5 is a subset of two-out-of-five codes. Unlike Industrial 2 of 5 code, Matrix 2 of 5 can encode data not only with black bars but with white spaces.
MicroPDF417 is two-dimensional (2D) stacked barcode symbology invented in 1996, by Frederick Schuessler, Kevin Hunter, Sundeep Kumar and Cary Chu from Symbol Technologies company. MicroPDF417 consists from specially encoded Row Address Patterns (RAP) columns and aligned to them Data columns encoded in "417" sequence which was invented in 1990. In 2006, the standard was registered as ISO/IEC 24728:2006.
Han Xin code is two-dimensional (2D) matrix barcode symbology invented in 2007 by Chinese company The Article Numbering Center of China to break monopoly of QR code. As QR code, Han Xin code consists of black squares and white square spaces arranged in a square grid on a white background. It has four finder patterns and other markers which allow to recognize it with camera-based readers. Han Xin code contains Reed–Solomon error correction with ability to read corrupted images. At this time, it is issued as ISO/IEC 20830:2021.
DotCode is two-dimensional (2D) matrix barcode invented in 2008 by Hand Held Products company to replace outdated Code 128. At this time, it is issued by Association for Automatic Identification and Mobility (AIM) as “ISS DotCode Symbology Specification 4.0”. DotCode consists of sparse black round dots and white spaces on white background. In case of black background round dots, creating barcode, can be white. DotCode was developed to use with high-speed industrial printers where printing accuracy can be low. Because DotCode by the standard does not require complicated elements like continuous lines or special shapes it can be applied with laser engraving or industrial drills.
Rectangular Micro QR Code is two-dimensional (2D) matrix barcode invented and standardized in 2022 by Denso Wave as ISO/IEC 23941. rMQR Code is designed as a rectangular variation of QR code and has the same parameters and applications as original QR code. But rMQR Code is more suitable for the rectangular areas and has difference between width and height up to 19 in R7x139 version. In this way it can be used in places where 1D barcodes are used. rMQR Code can replace Code 128 and Code 39 barcodes with more effective data encoding.
↑ "TBarcode1D_Code128". Han-soft corporation. Retrieved 2017-01-21. If a single "FNC 4" character is used, indicates the following data character in the symbol is an extended ASCII character. A 'SHIFT' character may follow the 'FNC 4' character if it is necessary to change character subset for the following data character. Subsequent data characters revert to the standard ASCII character set. If two consecutive 'FNC4' characters are used, all following data characters are extended ASCII characters until two further consecutive 'FNC4' characters are encountered or the end of the symbol is reached. If during this sequence of extended encodation a single "FNC4" character is encountered it is used to revert to standard ASCII encodation for the next data character only. 'SHIFT' and character subset characters shall have their normal effect during such a sequence.
↑ "Code 128 Explained". Softmatic GmbH. Retrieved 2017-01-21. In principle non-ASCII characters like German umlauts (e.g. ÄÖÜ) can be encoded in a Code 128 symbol by using a special character (FNC4). However, this feature is not widely supported. Using a 2D barcode symbology like Aztec or Datamatrix with dedicated support for non-ASCII data might be a better choice.
↑ GS1 General Specifications (January 2006–Version 7.0), section 5.3.1.1 GS1-128 Symbology Characteristics, stating, "Characters with ASCII values 128 to 255 may also be encoded in Code 128 Symbols. Characters with ASCII values 128 to 255 accessed by Function 4 Character (FNC4) are reserved for future use and are not used in GS1-128 Bar Code Symbols."
↑ "5.4.3.4.2 Function characters". GS1 General Specifications Standard. Version 23.0. GS1 AISBL: 287. Jan 2023. Retrieved June 28, 2023.
↑ GS1 General Specifications, Version 13, Issue 1, Jan-2013, Section 5.4.7.7. Use of Start, Code Set, and Shift symbols to Minimize Symbol Length (Informative), pages 268 to 269. This section gives the compression strategy.
↑ Skiena, Steven S. (2010). "8.9 War Story: Text Compression for Bar Codes". The Algorithm Design Manual (2nded.). Springer. ISBN978-1-849-96720-4. dynamic programming led to an 8% tighter encoding on average.
ZXing – Multiplatform open source barcode scanner / generator with versions available in Java (core project) and ports to ActionScript, C++, C#, ObjectiveC and Ruby.
Python Bar Code 128 – This code appears to draw boxes one pixel wide. It appears it was modified from a short line long line bar code which would have drawn lines. The "Black boxes" should be the same size as the "White Boxes".
GenCode128 – Free C# source code implementation of Code128. Almost all features are implemented, but is not 100% complete.
Barcode1DTools Ruby gem – Ruby source code for many 1D barcode symbologies including Code 128.
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