The way we have chosen to solve problems in this software, demand us to give every single variable a progressive order to advance our solution in time. If we look at our system of equations it is easy to see that u, v and T can be advanced in time by motion equations in each direction and by energy equation. To calculate pressure, we must know if we are dealing with compressible or incompressible flow. As we have stated before, we are going to solve problems with incompressible flow and only this case will be solved by csfl-lib-1.0.