How to create a profile histogram from a Ntuple
                                                           
      hi/file 2 rwn_aptuple.hbook                                                                                       
      zone 1 2                                                                                                          
      set MTYP 3                                                                                                        
1     NT/PLOT //LUN2/10.age%grade                                                                                
2     NT/PLOT //LUN2/10.age%grade option=prof                                                                    

1. The symbol ``%'' is used to produce multiple dimensional distributions with ntuples. The maximum number of dimension is 10. The command NT/PLOT produce a bi-dimensional distribution represented as a scatter plot with the current marker type.
2. When the option PROF is used, a profile histogram is produce. A profile histogram, is a 1D histogram which gives for each value of X the mean value of Y and its RMS (for more details see the HBOOK manual: routine HBPROF ).