What is the use of sim808.GPSdata.heading. How can we implement in a program.

Hi,
Need to know the use of sim808.GPSdata.heading. How can we implement in a program. Please can anyone help if implemented the use of sim808.GPSdata.heading
Thanks!
Need to know the use of sim808.GPSdata.heading. How can we implement in a program. Please can anyone help if implemented the use of sim808.GPSdata.heading
Thanks!