"Symbology" is the term used to describe the rules specifying the way that data is encoded into the bars and spaces. It is similar to a language. When humans communicate via the spoken or written word, any language can be used provided that both parties agree to and are proficient in the choice. The same concept is used in bar code. A bar code symbol consists of a number of printed bars and intervening spaces. The width of the bars and spaces, as well as the number of each, is determined by a specification for that symbology. Depending on the data to be communicated, several different symbologies can be used. There are two types of bar code symbologies: Continuous and Discrete. Discrete bar codes start with a bar, end with a bar, and have a space between characters, referred to as an intercharacter gap. Continuous bar codes start with a bar, end with a space, and have no intercharacter gap. The most popular symbologies are listed as follows:

If you want a detailed explanation of the symbology listed above, click on the corresponding symbology.

### Code 39 And Code 39 Mod 43

Code 39 was the first alphanumeric symbology to be developed. It is the most commonly used bar code symbology because it allows numbers, letters, and some punctuation to be bar coded. It is a discrete and variable length symbology. Every Code 39 character has five bars and four spaces. Every character encodation has three wide elements and six narrow elements out of nine total elements, hence the name. Any lower case letters in the input are automatically converted to upper case because Code 39 does not support lower case letters. The asterisk (*) is reserved for use as the start and stop character. Bar code symbols, which contain invalid characters, are replaced with a checked box to visually indicate the error. The Code 39 mod 43 symbol structure is the same as Code 39, with an additional data security check character appended. The check character is the modulus 43 sum of all the character values in a given data string. The list of valid characters for the Code 39 bar code includes:

- The capital letters
**A to Z**
- The numbers
**0 to 9**
- The
**space** character
- The symbols
**- . $ / + %**

### U.P.C. A

The Universal Product Code (U.P.C.,) has been successfully employed in the supermarket industry since 1973. It is designed to uniquely identify a product and its manufacturer. It is a fixed length, numeric, continuous symbology. Every character has four elements. The U.P.C., Version A (U.P.C., A) bar code is used to encode a 12 digit number. The first digit is the number system character, the next five are the manufacturer number, the next five are the product number, and the last digit is the checksum character.

### U.P.C. E0 And U.P.C. E1

U.P.C. E0 stands for Universal Product Code Version E zero. U.P.C. E0 is a zero suppression form of U.P.C. A and is used by pre-arrangement with the Uniform Code Council. The first character in this symbology, the number system character, is always 0 (zero). The ten digit input string consists of the five digit manufacturer's number and the five digit product code. The four rules for proper product numbers are as follows:

- If the last 3 digits in the Manufacturer's number are 000, 100, or 200, valid Product Code numbers are 00000-00999.
- If the last 3 digits in the Manufacturer's number are 300, 400, 500, 600, 700, 800 or 900 valid Product Code numbers are 00000-00099.
- If the last 2 digits in the Manufacturer's number are 10, 20, 30, 40, 50, 60, 70, 80 or 90, valid Product Code numbers are 00000-00009.
- If the Manufacturer's number does not end in zero (0), valid Product Code numbers are 00005-00009.

U.P.C. E1 stands for Universal Product Code Version E1, it is also a numeric only and fixed length code, and is typically used for shelf labeling in the Retail environment. The length of the input string for U.P.C. E1 is 6 numeric characters.

### EAN 13 And EAN 8

The European Article Numbering system (abbreviated as EAN) is a superset of U.P.C. An EAN scanner can decode U.P.C., but the reverse is not necessarily true.

EAN has two versions: EAN 13 and EAN 8, both are fixed length and numeric only. EAN 13 encodes 13 digits and EAN 8 encodes 8 digits.

### Code 93

Code 93 is an Alphanumeric, variable length and continuous symbology. Code 93 encodes all 128 ASCII characters. Forty-three of code 93's character set correspond to code 39's character set, and 4 additional characters are used as control characters when encoding the full ASCII character set in code 93's expanded mode. Each character is encoded with 9 modules composed in a pattern of 3 bars and 3 spaces. Each bar and space width may be one, two,three or four modules wide.

### Interleaved 2 of 5 And Interleaved 2 of 5 Mod 10

Interleaved 2 of 5 is a continuous, self-checking numeric symbology primarily used in industrial and retail applications. We use I 2 of 5 and I 2 of 5 Mod 10 to represent Interleaved 2 of 5 and Interleaved 2 of 5 Mod 10 respectively in the bar code font list. The Uniform Code Council recognizes the I 2 of 5 symbology for Shipping Container marking. I 2 of 5 pairs characters together and encodes the first of the pair in five bars and the second of the pair in the five interleaved spaces. In other words, all the odd-positioned data is encoded in bars, and all of the even-positioned data is encoded in the spaces. Two of five bars are wide, similarly two of five spaces are wide. A complete I 2 of 5 bar code symbol consists of the start code (two narrow bars and two narrow spaces), the data characters, and the stop code (one wide bar, a narrow space, and a narrow bar). I 2 of 5 requires an even number of digits to encode information. Interleaved 2 of 5 Mod 10 symbol structure is the same as I 2 of 5, with an additional data security check digit appended. The check digit is a modulus 10 sum. Interleaved 2 of 5 Mod 10 requires an odd number of digits to encode information.

### Code 128

Code 128 is variable length, continuous and alphanumeric symbology. Characters in Code 128 consists of three bars and three spaces such that the total character width is 11 modules. Bars and spaces may be one, two, three, or four modules wide. Code 128 B is a full alpha-numeric bar code that supports both upper and lower case character, plus four function control codes. The four function codes are inputted as follows:

Code 128 C is a numeric only bar code. UCC is the name given to a specially defined subset of Code 128; it is used most often for shipping containers. UCC is numeric only, always 19 data characters, starts with a special Function 1 character and includes a Mod 10 check digit.

### Codabar

Codabar is a discrete, variable length, self-checking symbology. Each character is represented by a standalone group of four bars and three intervening spaces. The character set of Codabar consists of 16 characters: the digits 0-9, and the special characters: $, :, /, ., +, -. There are four different start/stop characters (a, b, c, d) that are encoded as one bar and two spaces.

### MSI

MSI is a variable length, numeric only symbology. It is typically found on Shelf Pricing Labels in a Retail Store. This bar code always has a modulus 10 checksum at the end. We can also add an additional modulus 10 or modulus 11 checksum to the bar code before the final checksum. They are represented as MSI+10, MSI+10+10, MSI+11+10 respectively in the bar code font list