This variable determines whether or not keystrokes are inserted in front of any existing text when the user types an entry. Set this variable to 1 (on, true, yes) to enable insertion. The default value is 0 (off, false, no), which causes typing to replace existing text.
The user can change the state of INSERT_MODE with various key actions. For example, pressing <insert> can enable insertion. This variable has no affect on Windows controls.