A three-dot symbol used as a menu icon. The dots may be displayed horizontally or vertically. An ellipsis is also used at the end of a menu item to indicate that, if clicked, a submenu or dialog will be displayed. See hamburger icon
Ellipses Within a Menu
In this menu from the Windows version of this encyclopedia, "Picture Paths..." and "When a URL is clicked..." display a dialog box that requires input from the user.