If you have entered a value in the Leased Area field, then check the Derive Scale check box to adjust the mapping to match this value. For example, if the mapped NLA (Net Lettable Area) produces 2000 sqm, and the actual NLA on the lease is 1915, you can enter this value in the Leased Area field. The mapping will adjust the scale of mapping to make sure the area of spaces adjusts to this value.