Syntax:
test {terminal | palette}
test or test terminal creates a display of line and point styles and other useful things supported by the terminal you are currently using.
test palette plots profiles of R(z),G(z),B(z), where 04#4=z4#4=1. These are the
RGB components of the current color palette. It also plots the apparent net
intensity as calculated using NTSC coefficients to map RGB onto a grayscale.
The profile values are also loaded into a datablock named $PALETTE.