Replace and Insert Modes
When you enter data in input fields, two methods, or modes, for entering data are possible: replace and insert. In replace mode, you type over data (if there is any) that is to the right of the cursor. In insert mode, any data to the right of the cursor is moved to the right as you type.
In the standard system, entry mode is set to replace. And typically, you use the replace mode to enter data in input fields. But you can choose to switch to insert mode at any time; you use insert mode to insert data between existing data.
The status bar shows which mode you are currently in. It displays OVR when you are in replace mode and INS when you are in insert mode.
To switch entry modes press the INS (insert) key.
The entry mode displayed in the status bar changes to the new entry mode.
The INS key is a toggle between replace and insert modes, meaning that the entry mode changes each time you press the INS key.