mapserver/docs — pull request #2 by cnieman (2012-04-16 11:40:14+00:00)
Title: Added clarification to the use of "PALATTE_FORCE" in versions >= 6.0.

In MapServer < 6, setting a palette forcing it's use automatically used remaining palette space for anti-aliasing colours.

In MapServer >= 6, unless you add QUANTIZE_COLORS=a large enough number (such as 256-n colours in palette file), the only colours used to create the output image are those in the palette file.