Hotabs and hotemis are the coronal analogs of warmabs and photemis. In this case the free parameter determining the ionization is the log of the temperature in units of 10 K, i.e. logt4=0 corresponds to 10 K, logt4=3 corresponds to 10K.
The normalization is the same as for warmabs. The model supplies to xspec the emissivity of the gas, in units of erg cm s, times a factor 10. So the physical meaning of the normalization, , is
where EM is the emission measure of the gas in the source (at the temperature used in the fit) and D is the distance to the source.