Split window vertically  F8
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    Splits the screen at the current cursor location.  The current
    file is displayed in multiple windows.  Changes to a file are
    echoed in all windows opened to the same copy of that file.  You
    can also see any marked blocks in the same copy of the file in
    different windows.  There has to be at least 15 columns in any
    window, so the number of visible windows is limited by the display
    screen.