What does ParticleEmitter.Orientation do?

I know that the first two options here are all direction and y direction, but what does the remaining 2 options do?(VelocityPerpindicular and VelocityParallel)

VelocityPerpindicular the particle will look perpendicular to direction of it: image

VelocityParallel the particle will look parallel to direction of it: image

I know what perpendicular and parallel means but I can’t see any particles. What does “direction of it” mean? I tried rotating it, moving it in a direction, but I can never get the particles to spawn

Alright after more experimenting, I figured out that you need to give the particle speed for it to show up, and not the part itself… I’m not sure how I didn’t figure this out, but then again, in my opinion I think they should allow for the orientation of partials without velocity.