Split the current palette (if palette_name is not present) or the specified palette (if palette_name is present) into two parts; colors 0 to 99 will be a compressed version of the original, while colors 100 to 199 will be a gray scale. For details on the available palettes, see "palette: Set or Retrieve Palette" on page 21.
If you use split_palette to split the palette yourself, then be sure to call pl3tree with keyword split = 0, because otherwise pl3tree will split it again, with bizarre results. Alternatively, you can use the palette function referenced above to set the palette to your choice, then call pl3tree with split = 1.
In the above, the save3 function returns a copy of the current 3-D viewing transformation and lighting, so that the user can put it aside in the variable view. The _spin3 function does actually change the viewing transformation and lighting; the call to restore3 with argument view sets it back to its previous configuration.