What do the three (red, black, white) colored switches on manual typewriters mean?

I am shopping online for a manual typewriter. Many models, including surprisingly old ones, will have a switch with a red and black or, at times, red, black, and white options.

However, the ribbon in the machine will be all black, or black and red with no white (though there’s a white color).

Is the white for correction tape? If so, does the lack of correction tape on the ribbon mean someone put a black/red ribbon in it but it could theoretically hold white correction tape too?

I am seeing many older models, as old as the ‘40s, with that white option and I do not know what it means.