This variable allows character-based hosts to use color and video attributes to distinguish disabled screen controls from enabled controls. It can be set to a variety of numeric values that express combinations of attributes. When it is set to "0" (off, false, no), disabled controls appear the same as enabled ones. See section 6.4.9, "Common Screen Options, COLOR phrase" in Book 3, "Reference Manual," for a description of other numeric values that can be used.