Creating a new flight mode for ArduPlane


I was wondering about how I could integrate a new flight mode for ArduPlane. Any help would be appreciated.
The documentation is available for Copter, but I am confused about how to proceed for ArduPlane.

Also, where are the flight modes defined for ArduPlane in the code? In ArduCopter, there are specific files like control_guided,cpp etc. I don’t see such definations for ArduPlane.