  | 
          Load overlay file. Note that the upper button loads a
            single overlay file, clearing the current overlay. The lower
            button adds to the current overlay. 
           | 
        
        
            | 
          Save all overlays | 
        
        
            | 
          Save all overlays to a different file. Note that the upper
            button saves all overlays, the lower just the current one. | 
        
        
            | 
          Copy current overlay to clipboard | 
        
        
            | 
          Add another overlay from the clipboard | 
        
        
            | 
          Fix all parameters, i.e. set Float = "no" for all
            parameters. | 
        
        
            | 
          Cycle through units (cm-1, nm, MHz, Kelvin and
            eV), converting parameter values as appropriate each time.
            For overlays this is not normally required, as the the
            position units will be converted automatically to those
            selected for the main plot. Note also that in the overlays
            window the convert operation is applied to the currently
            selected object, not the entire tree of objects.  | 
        
        
            | 
          Add overlay from file. Note that the upper button loads a
            single overlay file, clearing the current overlay. | 
        
        
            | 
          Export current overlay to file. Note that the upper button
            saves all overlays, the lower just the current one. 
           | 
        
        
            | 
          Copy peaks to clipboard | 
        
        
            | 
          Delete peaks from this overlay | 
        
        
            | 
          Perform various operations on
            the spectrum; many of these can also be performed by right
            clicking on the overlay on the main window, if it is plotted
            separately from other traces. 
            
              
                
                  | Invert | 
                  Each the intensity at each point, I, becomes Imax
                    + Imin
                    - I 
                   | 
                 
                
                  | Crop | 
                  Discard points outside selected range, as
                    specified as FirstPoint
                    to LastPoint.
                    These can be set to the current visible region by
                    right clicking on the overlay in the main window and
                    selecting "Select Visible". 
                     | 
                 
                
                  | Find Zero | 
                  Uses a heuristic to attempt to set baseline
                    to the probable zero level of the spectrum. 
                   | 
                 
                
                  | Join To... | 
                  Add selected spectrum to the current spectrum; if
                    done from the main window the join point is at the
                    mouse position, otherwise any overlap region is
                    divided equally between the two spectra. 
                   | 
                 
                
                  | Join All,Unscaled | 
                  Join all spectra of this type together, ignoring
                    the vertical scaling | 
                 
                
                  | Join All,Scaled | 
                  Join all spectra of this type together, using the
                    vertical scaling | 
                 
                
                  | Smooth... | 
                  Smooth (and differentiate if required) the
                    spectrum. The method used is Savitzky-Golay
                    smoothing as originally described in A
                      Savitzky and MJE Golay, Anal Chem, 36,
                      1627 (1964). 
                   | 
                 
                
                  | Compress... | 
                  Compress the spectrum by either: 
                    
                      - averaging every n points together
 
                      - averaging all points within a specified
                        interval, to give points on a regular grid.
                        (This can expand the spectrum if the interval is
                        less than the starting interval.)
 
                       
                     
                    A dialog box allows the choice to be made. 
                   | 
                 
                
                  | Discard
                        Frequency | 
                  Replace frequency with point number | 
                 
                
                  | Discard
                        Intensity | 
                  Set Intensity to 1, and convert to linelist | 
                 
                
                  | Separate | 
                  Produce two independent intensity channels from
                    frequency and intensity | 
                 
                
                  | Swap x and y | 
                  Swap frequency and intensity channels | 
                 
              
             
           |