Postnet Barcode (Postal Numeric Encoding Technique)
Postnet barcode is widely used by the U.S Postal Service. It is a numeric symbology that uses five bars and four spaces. A constant width and spacing is used throughout the symbol. It is a clocked technology in which a scan through the bottom of the bars provides a timing track.
Postnet barcode encodes data in half and full-height bars. Most often, the delivery point is added, usually being the last two digits of the address or PO box number.