There's a mistake : in France, college is before high school Maternelle, primaire, collège, lycée, université = kindergarten, primary school, ?, highschool, university.

That's great, thanks !

Twitter offers a lot of tutorials on its video website : xvideos.com Check it out!

TBH I'm not sure I totally understand the question but projection is very useful to decompose the orientation of elements, like a cylinder that you just measured with a machine or a scanner. The coordinates and orientation (angles) can be projected in the three main planes XY, YZ and ZX.

I work in 3D metrology and the consensus is right handed and Z up. Had no idea left handed existed!