The "C" checksum character is the modulo 47 remainder of the sum of the weighted value of the data characters. The weighting value starts at "1" for the right-most data character, 2 for the second to last, 3 for the third-to-last, and so on up to 20. After 20, the sequence wraps around back to 1. In the above example (TEST93), the "C" checksum would be calculated as follows:

DATA	T	E	S	T	9	3
VALUE	29	14	28	29	9	3
WEIGHT	6	5	4	3	2	1
WEIGHTED SUM	174	70	112	87	18	3

Thus the sum of the individual weighted sums is 174 + 70 + 112 + 87 + 18 + 3 = 464. Modulo 47 gives a value of 9 with remainder 41. The value 41 is associated with the plus (+) sign, so the "C" check character would be encoded using the plus symbol encodation from the table below.

The "K" checksum character is calculated in basically the same way except that the weighting goes from 1 to 15. Also, the right-most character is now the "C" checksum character which was calculated in the step above.

DATA	T	E	S	T	9	3	+
VALUE	29	14	28	29	9	3	41
WEIGHT	7	6	5	4	3	2	1
WEIGHTED SUM	203	84	140	116	27	6	41

Thus the sum of the individual weighted sums is 203 + 84 + 140 + 116 + 27 + 6 + 41 = 617. Modulo 47 gives us a value of 13 with a remainder of 6. The value 6 is associated with the ASCII character "6", so the "K" check character would be encoded using the "6" symbol encodation from the table below.

In the following text, we will discuss the encoding of the bar code by considering that the number "1" represents a "dark" or "bar" section of the bar code whereas a "0" represents a "light" or "space" section of the bar code. Thus the numbers 1101 represents a double-wide bar (11), followed by a single-wide space (0), followed by a single-wide bar (1). This would be printed in the bar code as:

1. A start character , represented below by the asterisk (*) character.
2. Any number of characters encoded from the table below.
3. The "C" and "K" checksum digits calculated as described above and encoded using the table below.
4. A stop character, which is a second asterisk character.

Note that the characters ($), (%), (/), and (+) are special characters that are used to encode all 128 ASCII characters using Code 93's Full ASCII mode.

In Code 39, four of the characters ($, %, /, and +) are used to optionally encode all 128 characters-but there is no way to know whether those characters are being used as shift characters in Full ASCII mode or whether they are being used to represent $, %, /, and +. In Code 93 this problem is solved by reserving these four special characters exclusively to "shift" into Full ASCII mode.

1. The START character (*): 101011110.
2. The digit "T": enocded as 110100110.
3. The digit "E": enocded as 110010010.
4. The digit "S": enocded as 110101100.
5. The digit "T": enocded as 110100110.
6. The digit "9": enocded as 100001010.
7. The digit "3": enocded as 101000010.
8. The "C" check digit "+": enocded as 101110110.
9. The "K" check digit "6": enocded as 100100010.
10. The STOP character (*): 101011110.
11. Termination Bar: 1.

NOTE: In the above encoding example note that the last component, the termination bar (#11), follows the last character. This is because all characters, including the STOP character, end with a space-the final termination character is used to "terminate" the last character so that the width of the final space can be determined.