[ R, G, B, A ]
red, green, blue, and alpha
red, green and blue are obvious, the higher the alpha value is, the more "opaque" the colour becomes
16 is about the upper limit for any given colour value, and it's best to stick with low alpha values (1-4)
so for a nice purple vapor, you could do something like:
[ 14, 0, 16, 2 ]
remember, however, that this is all restricted by the actual TFTD palette, so some colours may not be fully achievable.
the algorithms do a "best match" according to the data in these fields and the colours available in the palettes.
(and now you know why "white" is written in inverted commas)