There are a few other classes of use in general, available in the header files of the ORSDK.
The transport controls (play, stop, and so on) in MotionBuilder can be accessed via a special class: FBPlayerControl. This class can be found in fbsystem.h.
The FBArrayTemplate class is a generic structure used to manage dynamic arrays. This alleviates all of the memory allocation problems, and is optimized to work with MotionBuilder.
