The physical model can be divided into two parts. On the one hand, there is the microscopic physics input-the specification of particle abundances and reaction cross sections. The microphysics in supernova models is continuously improving and many uncertainties remain to be resolved. However, in this methodological paper, we will only shortly summarize the ingredients that were standard at the time the code was written and hope that our code AGILE-BOLTZTRAN will continue to be useful in future discussions and evaluations of input physics improvements. On the other hand, there are the radiation hydrodynamics equations we are solving on the computer. They are the foundation of our implementation of neutrino transport and receive a detailed discussion later in this section.