Color 99 already has a special meaning, so it's out, but the rest could be used.
"What is color 99?" you might ask if you didn't already know, and also talk to yourself while reading other people's posts. It's "transparent" which, despite the way it sounds, simply means that if you want to, say, specify a background color, but leave the text color as whatever the default is for that kind of text, you use 99. Example:
//echo $color(info) -a default info text color on default bg color. $chr(3) $+ 99,2now default info text color on blue bg.