column-number-mode is an interactive compiled Lisp function in `simple.el'.

It is bound to <menu-bar> <options> <showhide> <column-number-mode>.

(column-number-mode &optional ARG)

Toggle column number display in the mode line (Column Number mode).
With a prefix argument ARG, enable Column Number mode if ARG is
positive, and disable it otherwise.

If called from Lisp, enable the mode if ARG is omitted or nil.