Code 93 was designed to provide a higher density and data security enhancement to Code39. It is an alphanumeric, variable length symbology. code93 is used primarily by Canadian postal office to encode supplementary delivery information. Every symbol includes two check characters.

Code93 is designed to encode 26 upper case letters, 10 digits and 7 special characters:
A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
0, 1, 2, 3, 4, 5, 6, 7, 8, 9
-, ., $, /, +, %, SPACE.

Each Code93 character is divided into nine modules and always has three bars and three spaces. In this way comes the symbology name.

In an open system, the minimum value of X dimension is 7.5 mils. the minimum bar height is 15 percent of the symbol length or 0.25 inches, whichever is greater. The starting and trailing quiet zone should be at least 0.25 inches.

Code 93 is also known as USS-93 (compressed form of Code 39).

A typical Code 93 barcode has the following structure:
1. A start character –
2. Message encoded
3. First check character "C"
4. Second check character "K"
5. Stop Character -
6. Termination bar

To calculate the check character "C" and "K", follow the following steps.
1. Take the value (0 through 47) of each character in the barcode (see the table to the left). The start and stop characters are not included in the checksum calculation.
2. Assign the weight for each character. The right-most character has a weight value of 1, the second to last 2 and so on. After 20, the sequence goes back to 1.
3. Multiply the character value with weight. Sum all the results.
4. Divide the result by 47 and get the remainder. Reverse look up the remainder to get the character. This is check character "C".
5. Append the "C" character at the end of the data, and repeat the step1 through step 4. This time the weight ranges from 1 to 15. The result is the character "K".

It is possible, using Code 93's "Full ASCII Mode" to encode all 128 ASCII characters. This is accomplished by using the ($), (/), (%), and (+) symbols as "shift" characters. Those characters combined with the single character that follows indicate which Full ASCII character is to be used.

The Extended Code 93 Encoding Table is identical to the Extended Code 39 Encoding Table except that Code 93 uses its four specialized shift characters ($), (/), (%), and (+) to shift to Full ASCII mode instead of Code 39 which isues the $, /, %, and + characters.

Use the Extended Code 39 Encoding Table for Extended Code 93 encoding, and just remember to use the special characters ($), (/), (%), and (+) whenever the Code 39 Encoding table refers to $, /, %, and +.