When using FXCOLOR, you should think in terms of attributes rather than
   colors.  Normally, they are the same thing.  However, if you change
   attribute 1, blue, to the color orange, it no longer has anything to do
   with blue.  Unfortunately, in Clipper, you must still refer to this
   attribute by the color symbol "b".  It would be much better if you could
   refer to it by attribute number rather than color symbol.  In that were
   the case, if you preferred the symbols, you could always use
   pre-processor #DEFINE's.  To maintain consistentcy with Clipper however,
   FXCOLOR will only accept the color symbols.  To do otherwise would just
   cause more confusion on top of the confusion you will encounter trying
   to remember what color symbol produces what color you've defined.

   As mentioned earlier, FXCOLOR uses 16 palettes of 16 attributes each.
   The palettes are referred to by the values 0 to 15.  Palette 0 is the
   primary palette used to determine the RGB definitions of attributes
   for those commands creating special effects.  For example, the command
   fx_Fade( "g" , "b" ) means to fade the RGB values of attribute 2 ("g")
   to the RGB values of attribute 1 ("b").  The RGB values for both
   attributes are taken from palette 0.  Thus, the RGB value of attribute
   2, as defined in palette 0, will fade to the RGB value of attribute 1,
   as defined in palette 0.

   RGB values are the RED, GREEN, and BLUE values that, when mixed in
   different proportions, produces colors on your monitor (refer to VGA.DOC
   for more info).  RGB values are specified in the range 0 to 63 and refer
   to the intensity of a particular primary color.