An iso-calculation line is a graph of the dependence of possible options for a certain parameter on another parameter. This graph shows all possible variations of a given parameter given another parameter. An isocopid line is a graphical representation of straight isocopids that do not intersect each other and represent all the isocopids of any system. If you build two isocopids for the heat distribution system across the volume of air in a room and carefully connect them, then you will get an isocopid line showing the change in heat distribution inside