BACKGROUND-INTENSITY* - This variable is used to choose a background intensity. Use one of these values:
0 --The runtime uses the default intensity, which is based on your hardware and operating environment. Under MS-DOS, the default background intensity is low-intensity. Under Windows, the default background intensity is high-intensity. The default value is "0".
1 --The runtime uses low-intensity.
2 --The runtime uses high-intensity.
There are two important exceptions:
The runtime always assigns low-intensity to the background if the background
color is black. Using high-intensity would cause the background to be dark
gray, which tends to make the screen look muddy.
Many devices do not support a background intensity independent from the
foreground intensity (most terminals, for example). When that is the case, the
runtime declares the background intensity to be low-intensity.