Insert And Overwrite Modes

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The EXPL editor has two modes for entering text: insert mode, and overwrite mode. Insert mode is the normal mode. When the editor is in this mode, existing characters are shifted to the right before a new character is inserted. This way no text is lost as new text is added. In overwrite mode a character to the right of the cursor is replaced whenever a new character is typed.


The editor starts in insert mode. Hitting the Insert key changes between insert and overwrite mode. When the editor is in insert mode, the letters “Ins” appear on the status line; and when in overwrite mode, the letters “Ovr” appear on the status line. Because overwrite mode can be dangerous, the “Ovr” symbol is yellow to alert you.


When in overwrite mode, pasting text and inserting the scoop overwrites the existing text. This can be useful in some instances and a disaster in others. The editor protects you as much as possible from overwrite errors. For example, it does not overwrite a carriage return. Also, it does not overwrite if the character you enter is a carriage return. This way, entering blank lines does not overwrite existing text.


The Backspace key works differently in overwrite mode. In overwrite mode Backspace replaces the deleted character with a space. This way, the text doesn’t shift. To prevent extraneous spaces from accumulating at the beginning of a line, Backspace does not replace carriage returns with a space—it just deletes them.