Code is a high-density linear barcode symbology defined in ISO/IEC It is used for alphanumeric or numeric-only barcodes. It can encode all. ISO/IEC Code bar code symbology specification. ISO/IEC Information technology — Automatic identification and data capture. BS ISO/IEC Information technology. Automatic identification and data capture techniques. Code bar code symbology.

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It is used for alphanumeric or numeric-only barcodes. The check symbol is calculated from a weighted sum modulo of all the symbols.

Code includes 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 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 casethe 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.

Code – Wikipedia

Despite its name, Code does not have distinct symbols, so it cannot represent code points directly. 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 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, in code sets A and C and in code sets B and C to switch between them:. The minimum width of the Quiet Zone to the left and right of the Bar Code is 10x, where x is the minimum width of a module.

It is mandatory at the left and right side of the barcode. 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 unitsthe sum of the widths of the spaces must be odd 3, 5 or 7 unitsand total 11 units per symbol.

For instance, encoding the ASCII character “0” can be viewed aswhere 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 indicates a bar three times as thick as a single 1 bar. There are possible 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 merged into a unit long stop pattern. Reading the stop pattern left to right is the stop pattern followed by a 2-unit barand reading the stop pattern right to left is the reverse stop pattern followed by a 2-unit bar.


The check digit is a weighted modulo checksum. It is calculated by summing the start code ‘value’ to the products of each symbol’s ‘value’ multiplied by its position in the barcode string.

The start symbol and first encoded symbol are in position 1. The sum of the products is then reduced modulo The remainder is then converted back 154417 one of the 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 variant A checksum value is calculated for the alphanumeric string PJJC:.

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.

The checksum is computed over the symbol values, without regard for which code set is active at the time. For instance the code set C value “33” and the code set B value “A” are both considered to be a Code value of 33, and the check digit is computed based on the value of 33 times the symbol’s position within the barcode.

If the following symbol is a shift, then a second symbol will be used to obtain the character. If two FNC4s are used consecutively then all following characters will be treated as such, up to the end of the string or another pair of FNC4s.

Code 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, lec or 4 ied modules.

Using the example above, an ‘A’ would be depicted with the patternor as widths 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 patternthe run lengths are 1 digit 11 digit 01 digit 13 digit 02 digit 13 digit 0. Reporting just the lengths of each run gives 1, 1, 1, 3, 2, 3, thereby producing a widths value of The “Code A”, “Code B” and “Code C” symbols cause all future symbols to be interpreted according to the corresponding subcode. The “Shift” symbol switches a single following symbol’s interpretation between subcodes A and B.

Especially the ASCII char of value 0 and of value 95 and above may be defined differently in the font that is installed.

The FNC x codes are used for special purposes. FNC1 at the beginning of a bar code indicates a GS bar code which begins with a 2- 3- or 4-digit application identifier assigned by the Uniform Code Councilwhich explains the following digits.

For example, application identifier indicates that an ISO numeric country code and ship-to postal code follows. For the end user, Code 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. Although code set C uses one code symbol to represent two digits, 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 only worth using if there are enough consecutive digits.

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 ” For example, given the string “xy23”, 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 be use a different code, set, but it makes no difference whether this is the first or last; 16 symbols are required in either case: 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 optimal encoding can be found using a dynamic programming algorithm. From Wikipedia, the free encyclopedia. However, this feature is not widely supported.

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 isso character is uso it is used to revert to standard ASCII encodation for the next data character only.

BS ISO/IEC 15417:2007

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