Vector PASS

Hi

I got some problem with motion vector pass.
Other 3D software makes vector pass with 2 channels.
Why blender make 4 channels? ( W, X. Y, Z)
If I want to use this passes for compositing, which is the right combination?

thanks

Tia

The right combination for compositing…what exactly? What are you trying to accomplish? Hard to tell you how to do something if you don’t tell us what you’re trying to do.