An exponential table model. The filename to be used should be given immediately after etable in the model command. For example
XSPEC> model etable{mymod.mod}
uses mymod.mod as the input for the model. XSPEC will multiply the contents of the model by -1 then take the exponential ie this model is for calculating absorption functions. For specifications of the table model file, see the OGIP memo 92-009 on the FITS file format for table model files (available on the WWW or by anonymous ftp from legacy.gsfc.nasa.gov under caldb/docs/memos).