This menu item toggles the line number display on the left hand side of the window.
The line numbers are shown in a fixed area on the left hand side of the Window for each file if this item is checked. The font used is automatically selected based on the current font and is slightly smaller than the selected font for display.
The color of the line numbers may be set with the Set Color dialog.
To print a file with line numbers, make the appropriate selection under the Page Setup dialog (File Menu).