A literal is any of: 
            
            
               
               - A character-string whose value is implied by the ordered set of characters of which it is composed 
 
               
               - A reserved word which references a figurative constant 
 
               
               
 A user-defined word which references a constant value 
                
               
            
            
            Every literal belongs to one of three types; nonnumeric, numeric and national.