In aVariable font, how is slider range set?

In a Variable font, how is slider range set?
If there are useful values beyond the value of a master, how would the slider be set to go to that value? Sometimes it is convenient to not draw masters at the extremes and things work fine.
If the value of a master on an axis is not the best start of a range, how would the slider be set to start at a different value within the extremes. Sometimes it is convenient to draw a master at an extreme that will never be used, for example a zero weight that will never be used.
Or, In a Variable font, do the masters have to be at the extremes to set the slider extremes?

For variable fonts, you need master at the extremes. They can’t extrapolate.