CLEAR SEGMENT

         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 updated  under  X-Window,  elsewhere
    use command ZOOM REFRESH to do it.

    CLEAR SEGMENT SegName makes the named segment invisible.

    One can erase a range of graphic segments in a single command by  typing
    a  range  of  segment  numbers,  as  in  CLEAR SEGMENT 24-16. The use of
    reverse range (24-16) forces the graphic library to actually delete  the
    segment,  if  possible,  instead  of  making  it  invisible. See command
    GTVL\CHANGE for details.