Values of parameter index can be within the range from 0 to %GetStTextRange+1
for status texts and its configuration parameter "Text usage" is set on
"Values".
Zero value (0) is in accordance with the color at field LOW
and the value %GetStTextRange+1 is in accordance with the color at
field HIGH.
Value of index -1 gets back a predefined color.
Different value of index generates an error ERR_RANGE_ERROR.
If the proper color component for required index is not defined, the
function gets back the invalid value.
Following rule can be
applied for really displayed color: If the color is not defined for
proper index (>=1), the color with index -1 will be used.