- Barcode is an optical machine-readable representation of data relating to object to which it is attached.
- Barcodes systematically represent data by varying the widths and spacings of parallel lines.
- The spaces and bars of a barcode are simplified language to speak with computer.
- Barcodes look strange but easily understood by computer.
- Barcode symbologies are "in-between" language which allows humans and computers to communicate.
- The mapping between messages and barcodes is called a symbology.
- It includes encoding of single digit/charecters of the message.
QR-Code
- QR code (abbreviated from Quick Response Code).
- The trademark for a type of matrix barcode (or two-dimensional barcode).
Code-39 (3 of 9)
- Code 39 barcode system is widely used in many industries.
- The code 39 charecter set includes digits 0-9, letters A-Z and symbols space, -, +, ., $, /, %.
- A special start/stop character is placed at the beginning and end of each barcode.
- Each charector consists of 9 elements.
- Each charecter 3 wide and 6 narrow elements.
- Characters are separated by an inter-character gap which is the same width as a narrow bar.
Code-128
- Code 128 is a very effective symbology which permits the encoding of alphanumeric data.
- It can encode all 128 charecters of ASCII.
- The symbology includes a checksum digit for verification.
- Bar code may also be verified character-by-character verifying the parity of each data byte.
- Quite zone is a clear area before and after the bars and spaces.
- Start code is one of three codes that signal the start of the Code 128 barcode.
- The Code 128 data is encoded in strips of bars and spaces.
- Checksum is a digit that verifies that the data just read in was correct.
- Stop code is the bar-and -space sequence that signals the end of code.
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