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Unformatted text preview: WHAT ARE SYMBOLOGIES? Symbologies are systems of encoding data such that a scanner and/or a decoding system may together read and decode the data encoded in the barcode. Aside from the actual technique of encoding the bars and spaces a number of technical specifications or characteristics define and separate one symbology from another. CHARACTER SET A Character Set refers to what data a given barcode symbology can encode. Generally, there are three types of character sets: Numeric, Alpha-numeric, and Full ASCII. A Numeric character set means the symbology can only encode numeric data from 0 through 9. Some additional characters may be encoded which are generally control features of the symbology, such as start/stop characters. A Alpha-Numeric character set means the symbology can encode the digits 0 through 9 as well as alphabetic characters from A through Z. Again, some additional characters may be encoded as start/stop characters. A Full ASCII character set is one that allows the encoding of the full ASCII character set. This implies any ASCII character, value 0 through 127, may be encoded by the symbology. In theory, a numeric character set will produce the smallest barcode whereas a Full ASCII character set will require more physical space to encode the same data. Of course, a Full ASCII symbology gives you more flexibility in encoding more types of information than a numeric symbology. DISCRETE/CONTINUOUS There are generally two types of barcode symbologies: discrete and continuous. A discrete symbology is one where each and every character encoded in the symbol may be interpeted individually without respect to the rest of the barcode. Such symbologies have characters that both start and end with a bar. Individual characters are separated by some amount of inter-character spacing. The intercharacter spacing carries no information-the only duty of the intercharacter spacing is to separate the characters. A continuous symbology is one in which the individual characters of the symbology cannot be interpreted by themselves. This is due to the fact that characters start with a bar and end with a space. The final space is "terminated" by the starting bar of the next character. A character cannot be taken individually since, individually, there is no way to know how wide the last space is without knowing where the next character begins. Continuous symbologies normally implement some kind of special termation bar or termination sequence such that the last space of the last data character is terminated by the termination bar....
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- Spring '08
- Universal Product Code, bar code, ASCII, check digit