%c -- print the current column number (this makes editing slower).
To make the column number update correctly in all cases,
`column-number-mode' must be non-nil.
+ %i -- print the size of the buffer.
+ %I -- like %i, but use k, M, G, etc., to abbreviate.
%p -- print percent of buffer above top of window, or Top, Bot or All.
%P -- print percent of buffer above bottom of window, perhaps plus Top,
or print Bottom or All.