specific surface area(Specific surface area "SSA" is a property of solids which is the total surface area of a material per unit of mass, solid or bulk volume, or cross-sectional area. WAD Alexander Demidov)
relative indicator(In most businesses, the use of relative indicators will form the vast majority of their KEPIs. These are sometimes referred to as "specific measures" – nibusinessinfo.co.uk (Northern Ireland) Tamerlane)