Merge pictures onto one plot
                                                                              
      histogram/file 1 pawhists.hbook                                                                                   
5     SWITCH Z                                                                                                   
1     PIC/CR MERGE2                                                                                              
      set htyp 354                                                                                                      
      hi/pl 110                                                                                                         
      set htyp 345                                                                                                      
      hi/pl 110(31:40) s                                                                                                
1     PIC/CR MERGE1                                                                                              
      set htyp 354                                                                                                      
      hi/pl 110(31:40)                                                                                                  
2     IZPICT MERGE2 C                                                                                            
      switch g                                                                                                          
3     PI/MERGE MERGE1 .5 .5 .3 D                                                                                 
4     PI/DEL *                                                                                                   

1. PI/CREATE allows to create a new graphic picture in memory. After this call, all the graphic generated
2. IZPICT is the generic function to perform all kind of actions on the HIGZ pictures. Here the picture MERGE2 is set as the current picture.
3. PI/MERGE allows to merge a picture into the current picture.
4. PI/DEL allows to delete a picture from memory. To delete a picture from a file the command SCRATCH should be used.
5. The command SWITCH set the graphics switch to control plotting output to terminal (G) and/or picture in memory (Z).