The model is a Raymond thermal spectrum, temperature range is 1 to 4 keV, element abundance table is cosmic (the other choice is Meyer), abundance of heavy elements (atomic number >2) is 100% of the value in the table (i.e. solar). Type ``help models'' for a list of other possible abundance fractions.
sp> fit Performing the simplex minimization fit. Observed spectrum [root_obs.tab]:} rp90 Model descriptor or ? for help: abs(17:19)*ray(1:4,c,100) # free parameters are # absorption, temperature, and normalization.