1 PLOT
  Syntax: PLOT[/option] id1[:id2] [&idb1:idb2]] [symb/col hatch/col patt/col]
      or  PLOT[/option] id part
      or  PLOT/NEXT [symb/col hatch/col patt/col]
   where: option   can be /CLEAR|/NOCLEAR|/NEXT/|/NTUPLE|/SMOOTH/|/EMPTY
          id       is the plot identifier
          idb      is the (optional) secondary identifier
          symb     is the symbol number to use (default from `SET SYMBOL')
          hatch    is the hatching to use (default from `SET HATCH')
          patt     is the pattern to use (default from `SET PATTERN')
          part     is the part of an HBOOK histogram that you want to plot
                   e.g. BANX, FUN etc.
          col      is the (optional) colour for the symbol, hatch or pattern.

  Alias for `HIST PLOT'.
  Plot a histogram on the currently  selected screen device. If you omit
  the secondary identifier, the default is used. You can plot a range of
  histograms  by  using the  syntax   `id1:id2' for  either or  both the
  primary and secondary identifiers.  To plot all histograms use the
  syntax `PLOT 0'. To plot the next histogram in memory use the form
  `PLOT/NEXT'.  The default option is `/CLEAR'. If you want  to add a
  second  plot as an  insert, for  example, use the `/NOCLEAR' qualifier
  and specify the size  and position of the second plot with  the
  `SET  X|Y  MARGIN and  SIZE'  commands. If the plot is within a window
  you  should  use  the `SET  X|Y  WMARGIN  and WSIZE' commands.

  Use `PLOT/NTUPLE' to plot variables from an Ntuple. You have to give the
  command `SET NTUPLE ...' first to specify the variables. Note that this
  form does not apply any cuts and is most useful for plotting different
  columns from a table of entries read in with `DAT_FETCH' for example.

  If you want to plot an empty frame, without any error messages, book a
  new histogram with `HISTOGRAM BOOK' and then plot it with `PLOT/EMPTY'.

  If you omit the symbol, hatch or pattern the default will be used. If you
  specify a symbol this only applies to the current plot command and will
  not change the default. Use `SET SYMBOL' to change the default. You
  can add the symbol, hatch or pattern color to the symbol number as a
  qualifier, e.g. `32/red' instead of just 32.

  If you are using a colour as a shading for an overlay and need to
  get the ticks redrawn use the `PLOT/NOCLEAR' command and redraw the
  1st histogram.

  The normal procedure is to `FETCH' the histograms from a file and
  then plot them using the above syntax.  You can also plot histograms
  directly from an HBOOK RZ file by opening the file (`OPEN' or
  `HB_OPEN') and then giving the plot command. This feature can be
  suppressed using the `SET AUTOFETCH OFF' command. Note that this
  only works for single histograms and not for a range nor for all
  histograms.

  If you want to check whether a histogram exists in a macro before
  deciding what to do you can use the following commands:

    SET PLOT ida&idb DEFAULT
    IF r121 = ida & r122 = idb
      ...
    ENDIF

  Note that this only works for histograms that you have tried to
  fetch. It does not yet work for histograms in an RZ file.

  Many other options for plotting 2-D histograms exist using the
  `2DIM' command. See HELP 2DIM for more details.

2 /CLEAR

  Default option.  Specifies that the screen  will be cleared before the
  next plot  is made.  Note that  if you  are  plotting with  more than 1
  window (see HELP SET WINDOW) this option will be overridden, except for
  the plot in the top lefthand corner (`WINDOW 1 1').

2 /NOCLEAR

  Specifies  that the screen  not be  cleared before  drawing this plot.
  This is useful if you  want to make inserts  and specify exactly where
  they should go and how big they should be (`SET X|Y MARGIN' and `SIZE'
  or `SET X|Y WMARGIN' and `WSIZE' commands). It can also be used if you
  make a plot with a pattern (or hatch -3), which obscures the scale. You
  can then say `PLOT/NOCLEAR id' for the 1st histogram again.

2 /EMPTY

  Draws an empty plot without giving an error message. This is useful
  if you want the frame of a plot for drawing in etc.

2 /NEXT

  Draws the next plot that is in memory. Useful for scanning a series of
  plots, following an `id' that you know.

2 /NTUPLE

  Draws the specified variables from an Ntuple. Use the `SET NTUPLE ...'
  command to specify which variables to put on which axis.

2 /SMOOTH

  Draws the plot as a smooth curve using a cubic spline interpolation
  between the points.

2 Examples

!\begin{enumerate}
!\item
!^
  Example 1:
  Use color shading as an overlay and put a black edge on all
  plots. Also put on a key in the same form:
    set colour symbol yellow
    plot 7 1 0 100
    set colour symbol green
    scale 6 6&1 0.9
    overlay 6&1 1 0 100
    set colour symbol black
    plot/noclear 7
    overlay 6&1 1
    ! Add a key with yellow symbol and black text
    key 7 new 8100 'Signal + background'
      10 15 0.4 = = cm -1004 yellow = = black
    ! This form works, but the above method is simpler
    key 7 new 2100 'Background'
      10 14 0.4 = = cm -1004 green = = black
    ! Draw a black edge around the symbol
    draw symbol 12 black 0.4
      10 14

!\item
!^
  Example 2:
  Same as part of the previous example with the colours in the `PLOT'
  command:
    ! Yellow symbol and black pattern - probably not what is wanted
    plot 7 1/yellow 0 100
    ! Other way round
    plot 7 1 0 100/yellow
    scale 6 6&1 0.9
    ! All in green
    overlay 6&1 1/green 0 100/green
    ! Default symbol colour is still black
    plot/noclear 7
    overlay 6&1 1/red


!\end{enumerate}

