All About the Intelligent Mail Barcode
The Intelligent Mail® barcode is a height-modulated barcode designed for use in high speed, automated, mail sortation machines that allow both the Planet Code® and POSTNET barcode information to be combined into a single barcode with expanded tracking capability.
Utilizing four different states of "bars" in the Intelligent Mail® barcode allows more information to be provided in this single barcode. The four possible states are:
Tracker (neither ascender nor descender) 
Full (both ascender and descender)
Ascender only
Descender only
Choose from the following tools to decode or encode tracking and delivery point ZIP Code™ Information:
The Decoder Tool helps you convert sequence of bars into meaningful tracking and delivery point ZIP information.
The Encoder Tool helps you to generate a barcode based on tracking and delivery point ZIP® information.