Interleaved 2 of 5
Interleaved 2 of 5 is a member of the Code 2 of 5 symbology family, which was first developed in 1968. It is sometimes referred to as ITF and forms the basis for the ITF-14 symbology that is widely used for shipping and transport logistics.
Interleaved 2 of 5 is often used instead of Code 39 - Regular because barcode messages that contain only numbers can be encoded in Interleaved 2 of 5 by using about half the space required by Code 39.
Interleaved 2 of 5 is defined in ISO/IEC 16390 Information technology - Automatic identification and data capture techniques - Interleaved 2 of 5 bar code symbology specification. For information about the GS1 implementation of ITF-14, see the GS1 General Specifications document.
The symbol comprises the following elements:
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Leading quiet zone
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Start pattern (narrow bar, narrow space, narrow bar, narrow space)
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One or more pairs of symbol characters that represent data (including an optional check digit)
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Stop pattern (wide bar, narrow space, narrow bar)
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Trailing quiet zone
Each Interleaved 2 of 5 character is represented by five elements: five bars or five spaces, two of which are wide and three narrow. The name "Interleaved 2 of 5" comes from the interleaving of the patterns of bars and spaces that represent the individual characters within the symbol: Characters are represented in pairs, and in every 10 elements, the five bars represent one character and the five spaces between them represent the next character.
All Interleaved 2 of 5 barcode messages must contain an even number of digits. Therefore, a leading zero will be added to the front of the barcode message in either of the following situations:
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The character message that is to be encoded contains an odd number of digits and the check digit is not in use
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The character message that is to be encoded contains an even number of digits and the check digit is in use
Interleaved 2 of 5 contains no intercharacter spaces.
This symbology supports all numeric digits (0-9).
Although this barcode is much denser than Code 39, the theoretical data security of Interleaved 2 of 5 is not quite as high. For this reason, we suggest that you always use Interleaved 2 of 5 with the optional check digit or that you standardize your barcodes on a single character length.
Interleaved 2 of 5 can contain an optional check digit that is based on the modulo 10 (mod 10) algorithm.
The recommended minimum symbol height for manual scanning is 5.0 mm or 15 percent of the symbol width (excluding quiet zones), whichever is greater. The quiet zones must be at least 10X wide, where "X" is the current X dimension.
The densest Interleaved 2 of 5 barcode that can be printed on an Epson or IBM-compatible dot-matrix printer is about nine characters per inch, not including the start and stop characters. On a laser printer, density can be increased to about 17 characters per inch. (For reading barcodes of this density, we recommend that you use a high-resolution optical scanner.)
Interleaved 2 of 5 barcodes can include bearer bars either as a rectangular frame around the barcode or as two perpendicular bars across the top and bottom of the data-expressing bars.
The term "bearer bars" originates with the manufacture of metal grates. The bearer bars in a grate bear weight and run perpendicular to the trans bars (which connect the bearer bars).
When barcodes are printed directly on corrugated cardboard boxes, flexible rubber printing plates are used. These plates often bend when they make contact with the cardboard, resulting in a distorted barcode. To prevent this bending, box printers stiffen the plates by adding bars perpendicular to the data-expressing bars. A side effect of stiffening the plates in this way is that the images of these additional bars are added to the printed barcode. By analogy with the bearer bars in metal grates, which run perpendicular to the trans bars, the additional bars in the barcode have come to be called "bearer bars" as well.
Bearer bars serve a secondary purpose: if a barcode reader passes over the barcode at too sharp an angle, there is a danger that it will not read data-expressing bars at the ends of the barcode. Since bearer bars can be used to prevent this, they are sometimes included even on barcodes that are being printed on a plain label with a label printer.
Symbol Structure