The FILENAME statement
                  associates a SAS fileref with an external text file or output device.
                  With 
 SAS/GRAPH software,
                  you can use a FILENAME statement to do the following tasks:   
                  
                  
                     
                        - 
                           
point to a text file that you want
                                 to use for data input or output.
                              
 
                            
                         
                        - 
                           
assign the destination of a graphics
                                 stream file (GSF). This destination can be either a single, specific
                                 file or an aggregate file storage location, such as directory or PDS. 
 See Exporting Your Output for information
                                       about creating graphics stream files. 
                               
                            
                         
                     
                   
                
               You can also use the
                  FILENAME statement to route input to and from other devices. For details,
                  see the SAS documentation for your operating environment.
               
 
               A FILENAME statement
                  that points to an external file has this general form:   
               
 
               
                  FILENAME fileref 'external-file';
                  
                
                   
                  
                  
                     
                     
                        
                           is the physical name
                              of the external file or aggregate file storage location that you want
                              to reference. For details about specifying the physical names of external
                              files, see the SAS documentation for your operating environment.