After lighting (whether enabled or not),
RGBA colors are clamped to the range 
.
For a color index,
the index is first converted to fixed-point with an unspecified number of bits
to the right of the binary point; the nearest fixed-point value is selected.
Then,
the bits to the right of the binary point are left alone while the
integer portion is
masked (bitwise ANDed) with 
,
where n is the number of bits in a color in the color index buffer
(buffers are discussed in chapter 4).