1 KEY
  Syntax: KEY command [nkey]
      or  KEY id [&idb] command [nkey]
          nsymb
          text
          x, y, size, angle, opt, mode, font, colour, thick, unit, tcolour
   where: id        is the histogram number the key applies to
          idb       is the optional secondary identifier
          command   can be ?|NEW|CHANGE|DELETE|LIST|END
          nkey      is the key number to change or delete
          nsymb     is the symbol number to describe
                    Use the form +/-(n000 + abs(nhat|npat))
                      where the sign is the sign of the hatch or
                      pattern number if you want a symbol which
                      includes a hatch or pattern
          text      is the text you want to display
          x,y       are the position of the key
          size      is the size of the text in cm (default = 0.4cm)
          angle     is in degrees with respect to the horizontal
          opt       can be: LEFT   Key is left adjusted (default)
                            CENTRE Key is centered
                            RIGHT  Key is right adjusted
          mode      can be: CM   = Position is in cm (default)
                            PLOT = Position in terms of plot coordinates
          font      is the font to use
          colour    is the colour number for the key
          thick     is the text thickness factor
          unit      is the segment size for drawing lines (default = 0.01)
                    Only works for symbols 5->8
          tcolour   is the text colour.

  When the `KEY' command is given in a file or a defined command, the last
  syntax must  always be used  and the key  number must be  given if it is
  applicable  to the  command  (`CHANGE or  DELETE'). You  always need the
  `END' command when reading from a file to exit `KEY' unless you give the
  `command' on the same line as `KEY'

  Keys are associated with histograms you have already
  plotted. Therefore, if you have only plotted one histogram on the
  picture (using the `PLOT', `2DIM', `LEGO', `SURFACE', `DISPLAY' or
  `OVERLAY/DIFF' commands - `OVERLAYS' on the same scale do not
  count), the syntax is the first line. If you have plotted more than
  one histogram on the display, you will be prompted for the
  identifier the key applies to.

  If you just give the command `KEY'  or `KEY id[&idb]' you will remain in
  `KEY' until you give  the `END' command or  `<CR>'. However, if you give
  some or all of the rest  of the `KEY' command  on the same line you will
  automatically exit `KEY' after you have finished the command.

  The position you give is where the symbol will be drawn. The text
  will be started twice the text size to the right of the symbol. The
  size of the symbol will be the same as the text size. If you do not
  give the text colour it will be the same as symbol colour. The text
  colour is useful for plots where you are using colour as a shading
  to print in black and white.

  If you want a symbol that includes a hatch or pattern use the symbol
  number in the form `+/-(n000 + abs(nhat|npat))'. `n' can be between
  1 and 8:
  +/-(1000+nhat) square symbol with hatch nhat
  +/-(2000+npat) square symbol with pattern npat
  +/-(3000+nhat) histogram symbol with hatch nhat
  +/-(4000+npat) histogram symbol with pattern npat
  +/-(5000+nhat) square symbol with hatch nhat
  +/-(6000+npat) square symbol with pattern npat
  +/-(7000+nhat) histogram symbol with hatch nhat
  +/-(8000+npat) histogram symbol with pattern npat

  The special values, 1000,3000,5000,7000 draw a filled symbol and the
  values 2000,4000,6000,8000 draw a hollow symbol. For values >=5000
  an edge is drawn round the symbol in the same colour as the
  text. Try the macro `exec MN_FIT_HELP:key' (VMS) or
  `exec $MN_FIT/help/key' (Unix) for some examples.

  If you use the option `SET MOUSE ON', then the position of the key
  is specified by the mouse. Move the mouse to where you want to have the
  key and click on the left button. To keep the key in the same
  position (if you are changing it) click on the right mouse button.
  Note that using the mouse only works properly in `CM' mode.

  By default the text will be written using the HIGZ routine
  IGTEXT. For details on formatting text and the other fonts available
  see HELP Text. The default colour and thickness of the comments are
  the same as the title.

  For `mode CM', `x=0, y=0' is the bottom left-hand corner of the
  picture You can omit all of the parameters except x and y for a new
  key. The option for the key will always be set to `LEFT', whether
  you try to change it or not.  If you change or delete a key, use the
  command `REDRAW' to see the effect of what you have done.

