I'm confused here.
For the pilot, the gauge displays a number of some description which, for any given stage of flight, configuration, etc., needs to be kept between a minimum and maximum value via pilot intervention. A good pilot manages to keep the number somewhere near a desired value at any given time.
Whether the actual number is IAS, CAS, apples or oranges, is rather moot.
Different matter if we are talking engineering stuff, of course.