1.3—Rules of construction.
               		
               		
               	 	
               	 	
               	 	
               	 		
    
        
        (a) 
         In Subchapters A through K of this chapter, unless the context requires otherwise:
     
    
        
        (1) 
         Words importing the singular include the plural;
     
    
        
        (2) 
         Words importing the plural include the singular; and
     
    
        
        (3) 
         Words importing the masculine gender include the feminine.
     
    
        
        (b) 
         In Subchapters A through K of this chapter, the word:
     
    
        
        (1) 
        
            Shall is used in an imperative sense;
     
    
        
        (2) 
        
            May is used in a permissive sense to state authority or permission to do the act prescribed, and the words “no person may * * *” or “a person may not * * *” mean that no person is required, authorized, or permitted to do the act prescribed; and
     
    
        
        (3) 
        
            Includes means “includes but is not limited to”.
     
    
        
            Code of Federal Regulations
        
        [Doc. No. 1150, 27 FR 4590, May 15, 1962, as amended by Amdt. 1-10, 31 FR 5055, Mar. 29, 1966]