CHANGE

        [GTVL\]CHANGE Item SegName Value [Val2 [Val3]]
        [GTVL\]CHANGE Behaviour Value

    Changes  some  attribute  of  the Graphic Library. Two items concern the
    current directory and active windows:
      - CHANGE DIRECTORY [DirName [WinNum]]
          changes the default directory to DirName (default is to change  to
          the  top  directory),  and  optionally the active window number to
          WinNum (instead of 1) within this directory. The  current  working
          directory  is  stored  as  a  character string in the SIC variable
          GTV%PWD.
      - CHANGE WINDOW WinNum|ZOOM
          changes the active window number to WinNum or to the ZOOM  window.
          The active window is in particular the one in which the cursor ap-
          pears for commands which use it.

    Some other items are image segment attributes:
      - CHANGE SCALING    SegName LIN|LOG [Lcut [Hcut]]
          will change the transfer function for the specified image segment.
      - CHANGE BLANKING   SegName BLACK|WHITE|Colour
          will change the colour of blanked pixels (if any) in the displayed
          image. Colour is a colour value as in PENCIL command (1-8).
      - CHANGE COLOUR     SegName Value
      - CHANGE DASH       SegName Value
      - CHANGE DEPTH      SegName Value. See subtopic for details.
      - CHANGE VISIBILITY SegName ON|OFF
      - CHANGE WEIGHT     SegName Value
    The  last  five items are general segment attributes. For these, if Seg-
    Name is a segment, only that segment is modified, but if it is a  direc-
    tory,  all segments attached to this directory are modified accordingly.
    See subtopic SEGMENT_NAMES for details on naming segments.

    And finally, some general behaviours can be changed will  the  following
    keywords:
      - CHANGE LUT STATIC|DYNAMIC
          toggles  the  Look-Up-Tables to STATIC or DYNAMIC mode. Default is
          DYNAMIC. See subtopic LUT for details.
      - CHANGE PENCIL HARD|SOFT
          specifies whether the GTV library should use  the  (output  depen-
          dent)  hardware  generator for dashes and thickness, or whether it
          should use its own (output independent) software emulation.  Hard-
          ware  generator  may (or may not) produce nicer output, and may be
          faster...
      - CHANGE POSITION
          changes the window position on the screen. See  subtopic  for  de-
          tails.