[modeller_usage] Loop model refinement level

In the example taken from http://salilab.org/modeller/manual/node32.html, the loop refinement level is set to "fast"

a.loop.md_level = refine.fast # Loop model refinement level

What other levels of refinement do I have access to? I've seen in other examples something like the following for complete models:

# Very thorough VTFM optimization: a.library_schedule = autosched.slow a.max_var_iterations = 300 # Very thorough MD optimization: a.md_level = refine.very_slow # Repeat the whole cycle 3-times and do not stop unless obj.func. > 1E6 a.repeat_optimization = 3 a.max_molpdf = 1e8

Would this also apply for loops? Would it make much difference in terms of final model/loop quality (DOPE score maybe)?

Thanks again for all your help.