PostNet was developed by the United States Postal Service (USPS) to allow faster mail sorting and routing. PostNet codes are the familiar and unusual looking bar codes often printed on envelopes and business return mail.
Unlike most other barcodes, in which data is encoded in the width of the bars and spaces, PostNet actually encodes data in the height of the bars. That's why all the bars are of the same width, but not the same height.
The are no properties specific to the PostNet barcode type.