Interleaved 2 of 5 Barcodes
Interleaved 2 of 5 (ITF) barcodes are two-width numeric codes that can encode information of any length, as long as there is an even number of digits in the code. Information is encoded based on the width of the bars and spaces, and exactly 2 out of every 5 bars are wide. Their predecessor, the Standard or Industrial 2 of 5 barcode, could encode information only in the width of the bars, but not the spaces. ITF barcodes are generally used for distribution and warehouse identification purposes. They are often used to identify cartons or crates which themselves contain items with their own UPC barcodes. Additionally, they are often used to label 135 film.
Specifications: The Interleaved 2 of 5 barcode begins with a start character, to indicate the beginning of the code. Then comes the encoded data, followed by an optional check digit, and the stop character. The ITF barcode can only encode an even number of digits, since each character is made up of two interleaving digits. If a code has an odd number of digits, a zero is added to the front of the barcode.
Advantages: The Interleaved 2 of 5 barcode can encode more information than the regular 2 of 5 code, as it utilizes the spaces as well as the bars themselves. Additionally, it is self-checking and does not require a check digit, though one can be added.
Disadvantages: It cannot encode letters, only numbers.