Code 11
Code 11 is used primarily for labeling telecommunications equipment. The character set
includes the digits 0 through 9, a dash (  ), and a start/stop code. Each character is
encoded with three bars and two spaces. Of these five elements, there may be two
wide and three narrow, or one wide and four narrow. Wide elements represent a binary
1 while narrow elements represent a binary 0.
Character 
Bar 
Space 
Bar 
Space 
Bar 
0 
0 
0 
0 
0 
1 
1 
1 
0 
0 
0 
1 
2 
0 
1 
0 
0 
1 
3 
1 
1 
0 
0 
0 
4 
0 
0 
1 
0 
1 
5 
1 
0 
1 
0 
0 
6 
0 
1 
1 
0 
0 
7 
0 
0 
0 
1 
1 
8 
1 
0 
0 
1 
0 
9 
1 
0 
0 
0 
0 
 
0 
0 
1 
0 
0 
S/S 
0 
0 
1 
1 
0 
Two check digits, named C and K, are used; often only the first check digit (C) is used when
the length of the data is 10 characters
or fewer. The check digits are the result of a Modulo 11 division of the sum of the
products of each digit times a weight factor. The weights for the C check digit
range from 1 to 10 while the weights for the K check digit range from 1 to 9.
Weights start at the right end of the data and increment towards the left. The dash
character has a value of 10 for purposes of check digit calculation.

Starting at the right end of the data, assign a weight to each character starting with 1
and incrementing to 10.
If the data is longer than 10 characters, cycle back to 1
and continue.

Calculate the product of each data character times its weight. For the dash use a
character value of 10.
 Sum the products, divide by 11, and take the remainder
 Append the result of Step 3 to the end of the data.

Starting at the right end of the data which now includes the C check digit, assign a
weight to each character starting with 1 and incrementing to 9. If the data is
longer than 9 characters, cycle back to 1 and continue.
 Calculate the product of each data character times its weight.
 Sum the products, divide by 11, and take the remainder.
Format the complete barcode by concatenating a start character + data + C + K + stop character.