Q&A: X-ray Astronomy
I quote from http://chandra.harvard.edu/photo/2000/0170/index.html:
"The Roman numerals refer to how many electrons have been
stripped from the atoms. e.g. OVIII is an ion that has lost 7
electrons from its atomic shell, NeX has lost 9 electrons, etc."
This does not make sense. Do you mean OVIII has lost eight
electrons and NeX has lost ten?
Blame it on the Romans for not inventing zero. The neutral
atoms, with zero electrons removed are labeled with I. For
example HI for a neutral hydrogen atom, OI for a neutral oxygen