Particularly ones that can apply to mudlord's patch.
Everything I've found on the net has been of no real help to me, I've just been figuring it out on my own.
because "float 4" is a collection of 4 different variables. and your 0.2 and 0.9 are only a single dimension variable.
the second example splits it off into its component parts (.r, .g, .b). But even then the second example is still a bit fishy, but hey, it compiles, right?
that's not to say they probably have some "brightness" function that will take a color array and return a single dimension variable that can then be compared with a single constant.