Just noticed that the links given in version 10 of the Argo user manual for updating Comet and Asteroid elements give a 404 error.
http://www.cfa.harvard.edu/iau/ephem...arecomets.html
http://www.cfa.harvard.edu/iau/ephem...ftwareels.html
???
This seems to be the correct link for the comets:
http://www.cfa.harvard.edu/iau/Ephem.../Soft06Cmt.txt
gb.