CLEAR

 

        CLEAR [Arg]

      - CLEAR ALPHA erases the alphanumeric screen alone, without  affecting
        the  plot.  If  possible,  rather than erasing the alpha screen, the
        graphic screen is raised up.
      - CLEAR DIRECTORY [DirName] makes the named directory (or  by  default
        the current directory) invisible. All the attached structure becomes
        invisible.  The Graphic screen is  not  updated,  use  command  ZOOM
        REFRESH  to do it. Note that the directory is not destroyed: you can
        recover it by a CHANGE VISIBILITY command.
      - CLEAR GRAPHIC lowers the  graphic  windows,  popping  up  the  alpha
        screen.
      - CLEAR PLOT destroys the current tree or the whole plot,  and  clears
        the  graphic  screen  accordingly.  The  default  behaviour  can  be
        controlled by command CHANGE CLEAR.
      - CLEAR SEGMENT destroys the last graphic segment, i.e.  the  part  of
        the  plot  corresponding  to  the last graphic command.  Can be used
        repetitively. The Graphic screen is not updated,  use  command  ZOOM
        REFRESH to do it.
      - CLEAR SEGMENT  SegName  makes  the  named  segment  invisible.   The
        Graphic  screen  is  not updated, use command ZOOM REFRESH to do it.
        This is equivalent to CHANGE VISIBILITY SegName OFF.
      - CLEAR TREE clears the current tree only, leaving all other  parallel
        trees  intact. All associated windows are destroyed, and the tree is
        is recreated empty, with a single attached window. If only one  tree
        exist, a CLEAR WHOLE is performed.
      - CLEAR WHOLE destroys the  whole  plot.  On  X-Window  displays,  all
        windows  are  destroyed, and a new window is recreated for the first
        tree. Other trees are destroyed.
      - CLEAR WINDOW delete the current graphic window (if possible).   Only
        supported on multi-window displays (X-Window).
      - CLEAR prompts the user for confirmation. In non interactive session,
        it clears the plot without prompting.