TYPE: POP
TITLE: Up Vector POP

The Up Vector POP can be used to define the particle frame of reference 
up vector. The velocity defines the z direction. The up vector defines the
y direction and the cross product of the two define the x direction. 
The particle frame of reference is used to orient geometry instanced
on the particle. The up vector can be evaluated either in component form
or as a vector.

This POP modifies the following attributes: up.

Parameters:
    Activation          - Turns the POP on and off	/activate
    Source Group        - Subset of points to act on
    Apply Motion        - Type of points to apply up vector to
    Up Vector           - Up vector 			/upx /upy /upz

Local Variables 
    Overview - The standard local variables are usable in this POP.  Please
               refer to the Houdini manual for more details.
