picture-tab
picture-tab is an interactive compiled Lisp function in `picture.el
'.
(picture-tab &optional ARG)
Tab transparently (just move point) to next tab stop.
With prefix arg, overwrite the traversed text with spaces. The tab stop
list can be changed by M-x picture-set-tab-stops and M-x edit-tab-stops.
See also documentation for variable `picture-tab-chars'.