Got some idea. In my words
DOS -lines end with \r\n
UNIX -lines end with \n
MAC -lines end with \r
If you open a file & all lines don't end in \r\n then fileformat remains unix not DOS.Similiarly all \r means MAC.
You can type \r by 'ctrl+v' then 'enter'
If you edited unix text file in windows notepad then you will see ^M (i.e \r) in that file.
(1)press ctrl+g (to see how many lines your document have & %th position of current line)
(2)press 'g' then 'ctrl+g' .Now you see current line number,column,word & byte position.(I agree :set ruler will show line number & column at bottom right . So the extra info was words & bytes).
Okay , I went out of context.