[geometry] "A 2D or a 3D point can be represented by the fo..."

[JimJJewett]

https://www.w3.org/TR/geometry-1/#DOMPoint

A 2D or a 3D point can be represented by the following WebIDL interfaces:​

There is no indication of how to interpret x, y, z, or w. I presume that x is typically rightward distance from the left of the screen/picture, y is typically upward distance from the bottom, and z is an indication of depth. My uncertainty about the meaning of perspective is the reason I noticed this problem.