Land usage is just what it says. How is land used. There are a few factors that determine how land is used. Physical characteristics, area amenities, climate, weather, and the government bodies that dictates what is allowed.
This Article is not to be viewed as providing legal advice.
This is an appraisal principle to obtain highest value of a property. The maximum Legally allowable productivity with the greatest net return is determined. This might not be allowable with current zoning, however if it is reasonable to assume that a variance is obtainable the value may be based upon the ROI of what the variance would allow.