This section explains the mechanism for user-specified tab stops and the mechanisms that use and set them. The name “tab stops” is used because the feature is similar to that of the tab stops on a typewriter. The feature works by inserting an appropriate number of spaces and tab characters to reach the next tab stop column; it does not affect the display of tab characters in the buffer (see Usual Display Conventions). Note that the TAB character as input uses this tab stop feature only in a few major modes, such as Text mode. See Tab Stops in The GNU Emacs Manual.
This command inserts spaces or tabs before point, up to the next tab
stop column defined by tab-stop-list.
This variable defines the tab stop columns used by tab-to-tab-stop.
It should be either nil, or a list of increasing integers,
which need not be evenly spaced. The list is implicitly
extended to infinity through repetition of the interval between the
last and penultimate elements (or tab-width if the list has
fewer than two elements). A value of nil means a tab stop
every tab-width columns.
Use M-x edit-tab-stops to edit the location of tab stops interactively.