Constants

x y z w

Don't use "w" in 3D, of course. See below for info about how the axes are oriented.

Directions

x+ y+ z+ w+
x- y- z- w-

A direction is an axis plus a sign. When you first load a new file, the x axis points to the right and the y axis points upward.

In 3D, the coordinate system is left-handed, so the z axis points away from you.

In 4D, the overall coordinate system is probably also left-handed, but the z axis points in the "out" direction and looks right-handed. The w axis points away from you.

Colors

The following colors are predefined. Other colors can be entered with the HTML syntax #RRGGBB.

red     cyan      orange
green   magenta   gray
blue    yellow    white

Boolean Constants

true false

The Null Constant

The command "null" puts a null on the stack. The alias "?" is also defined for backward compatibility.