plane(axis, index)

In 3D only.

Permits to select a plane from the 3D buffer and copies it to the 2D
buffer. Axis is either F1, F2 or F3 as the axis orthogonal to the
chosen plane. Thus F1 selects plane F23, etc...

see also : vert row col diag dim

NPK Documentation, version 0.995 - 2009-10-14