Barcode encyclopedia : Symbology postbarKnown as Postbar or CPC 4 - State, used in Canada Post
Derived from British Royal Mail, uses series of bars ( Tracker, Ascender, Descender, Full height ) each one have one of 4 states. Each bar is centered (tracker), medium and elevated (ascender), medium and lowered (descender) or full height.
The symbology is known as a Data Content Identifier (DCI).
This code used also Reed Solomonerror correction techniques,if the particular of code is destroyed, information is still decoded good.