Numerical input of settings/units in Rooms menu is confusing.
For the metric scale types, Areas, Volumes and Perimeters are measured in square meters, cubic meters and linear meters irrespective of the metric scale type selected. The Room Settings menu allows you to set the number of decimals to display for each and to provide the selected descriptor for the display of the unit, such as sq m, m?, square meters etc. - it basically gives the user the freedom to decide what the unit display will look like.