The code 11 barcode was developed by Intermec in 1977. Used in the telecommunications field.

This barcode is dense and can encode strings of any length consisting of numbers 0-9 and dash characters. Code 11 uses one or two check digits and two check symbols. Normally, if the string is 10 symbols or less in length, use only one check symbol. If the string is longer than 10 symbols, use two check symbols. The value of the check symbol is calculated by the modulo 10 algorithm.

"Code 11" barcode. "12345-6789" is the number encoded in the barcode.