This page discusses terminology regarding Enigmata
Volume of FireEdit
The volume of fire is a relationship between how much fire a particular base is able to output at a certain range relationship. This regards that for example, if a base is composed solely of rows of units that have identical damage models, the front row units only having longer range, the second with normal range, the third with shorter range. At different ranges, that base is able to put out a different volume of fire. At long range it can only output so much. At medium range, the outer and middle rows overlap their fields of fire, and so on. This is an important factor in deciding what radius to place some units at.
Unit surface areaEdit
Surface area regards how much your units are exposed. It is a non-specific term, that is, too many different factors may influence what the idea of unit surface area may be. It simply in general regards how much you are exposed in one direction. This factor can be influenced by concentration of healers, unit health in a specific area, and number of units.