This routine returns the PDB or mmCIF file name of each generated model, usually of the form 'foo.B000X000Y.pdb' (where root_name (or sequence)=foo, id1=X, id2=Y, and file_ext=.pdb). You can redefine this routine if you don't like the standard naming scheme. For typical automodel usage, id1 is a constant and id2 is the model number, running from automodel.starting_model to automodel.ending_model.
See also loopmodel.get_loop_model_filename() and automodel.set_output_model_format().