A. Listed below are characteristics that most bar codes have in common:
Bars and Spaces - Each symbol has a defined pattern of bars and spaces that can be read or scanned by a bar code reader. The width of both bars and spaces vary allowing the representation of different characters. The height of the bars has interpretive information, yet provides data redundancy so that the scanner is not limited to a single scan path.
Character Set - Each bar code symbology has its own defined character set. In some cases these sets are alphanumeric with the addition of some special characters, while other symbologies only allow for the encodation of the digits 0 through to 9.
Human Readable Information - The information encoded in a bar code may be represented in a human-readable form above or below the printed bar code symbol. This human-readable representation is optional with some codes, while mandatory with others.
Fixed vs Variable Length - Some bar code symbologies vary in length, contingent upon the amount of information that needs to be represented. Other symbologies have a fixed length and always contain the same amount of encoded information.
"X" Dimension - Each bar code symbol has a defined "X" dimension, or narrow bar. This bar is measured in thousandths of an inch (or "mils") and directly affects the physical size of bar code.
Modular vs Binary - With a modular bar code, information is encoded using bars and spaces that vary from one to four.