The ionizing spectrum has the obvious effect of creating ionization in the gas. But it also can influence the heating and cooling via Compton scattering if the gas is highly ionized. The standard ionizing spectrum options apply to all the energies in the grid. Therefore if, for example, an power law is chosen the temperature in Compton equilibrium will be kT= , and power law indeces which are greater (or less) than 1 will be influenced even more strongly by the choice of minimum (or maximum) energy. It is likely that the choice we have made in designing the code will not be the choice which is physically appropriate for the situation of interest, so the user is encouraged to input the spectral model from a file, with the appropriate cutoffs built in, in situations where power law spectra and Compton heating/cooling are important.