CHANGE

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

    Change some attribute of the Graphic Library. Three  items  concern  the
    current directory and active windows:
      - CHANGE DIRECTORY DirName [WinNum] change the  default  directory  to
        DirName,  and optionally the active window number to WinNum (instead
        of 0) within this directory.
      - CHANGE WINDOW WinNum [NOREFRESH|REFRESH] change  the  active  window
        number  to  WinNum,  and  optionally  change  its  automatic refresh
        behaviour.
      - CHANGE ZOOM NEW|CURRENT change the default ZOOM command behaviour.
      - CHANGE CLEAR  TREE|WHOLE  change  the  default  CLEAR  PLOT  command
        behaviour.

    Two 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).

    Other items are general  segment  attributes:  WEIGHT,  DASHED,  COLOUR,
    DEPTH, VISIBILITY (ON or OFF). For these items, if SegName is a segment,
    only that segment is modified, but if it is a  directory,  all  segments
    attached to this directory are modified accordingly.