   Quaternion what is that, I want the character to jump.
  Here is the list of C codes from 3D rad. http://www.3drad.com/Script_reference.htmI have a gravity object that affect the gravity of a character. I want to make it jump. So I need to reverse the orientation of that object (pointing down) to pointing up, a 180° rotation.Maybe I will use this in my script, but I don't know what is QuaternioniObjectOrientationSet(OBJ_X,Quaternion)   Set the specified object orientation (defined as a quaternion).   OBJ_X = object handle.   Quaternion = orientation.   NOTE: this function will only work with objects that support dynamic orientation setting, like    SkinMesh, Particles, etc. Objects supporting physics do not usually work with this function.    For example, you should not use this function to progressively alter the orientation of a RigidBody or a Car,    to make it spin. You should use the Force object instead.   
  Why are you trying to do this with quaternions?  In the text your provided, it says "Objects supporting physics do not usually work with this function."  If you're trying to make a character jump, apply a force to it.However, if you're still curious, quaternions are extentions of the complex numbers into 4-dimensions.  In game development, they're generally used to represent rotations.   