This parameter controls the time step to print out the spectrum. 1 is a bare-bone version with black bodies, good only for tests. 2 uses the Kurucz models as compiled by Lejeune for all stars. 3 uses Lejeune for stars with plane-parallel atmospheres and Schmutz for stars with strong winds. 3 is the recommended value.
Detailed explanations are in the sp-feature subroutine.
Some of the subroutines are interrelated. If you choose such a subroutine but not the other, required one, a warning will be issued. The 14 output flags are explained in the next section. The output Computation of the number of ionizing photons. Output is the number of ionizing photons in the HI, HeI, and HeII continuum, their fractions relative to the total luminosity, and the total luminosity.