Code 11 is a barcode symbology developed by Intermec in 1977, and it is used primarily in telecommunications. The symbol can encode any length string consisting of the digits 0–9 and the dash character (-). A twelfth code represents the start/stop character, commonly printed as "*". One or two modulo-11 check digit(s) can be included.
It is a discrete, binary symbology where each digit consists of three bars and two spaces; a single narrow space separates consecutive symbols. The width of a digit is not fixed; three digits (0, 9 and -) have one wide element, while the others have two wide elements.
The valid codes have one wide bar, and may have one additional wide element (bar or space).
+ Code 11 digits Character Widths Barcode 0 00001101011 1 100011101011 2 010011001011 3 110001100101 4 001011011011 5 101001101101601100100110170001110100118100101101001910000110101 -00100101101Stop/Start001101011001
+ Code 11 decoding Wideelement Wide bar Left Middle Right Left bar 9 5 1 Left space 3 6 2 Middle bar 5 - 4 Right space 8 * 7 Right bar 1 4 0 The decode table has 15 entries because the symbols with two wide bars (1, 4 and 5) are listed twice.
Assuming narrow elements are one unit wide and wide elements are two units, the average digit is 7.8 units. This is better than codes with a larger repertoire like Codabar (10 units) or Code 39 (11 units), but not quite as good as interleaved 2 of 5 (7 units). The non-binary symbology Code 128 uses 5.5 units per digit (11 units per digit pair).
External links Code 11 Symbology Specification