are some sections of the sds that are not mandatory?
['Section 1: Product/Chemical Identification. ... ', 'Section 2: Hazard Identification. ... ', 'Section 3: Composition of the Chemical. ... ', 'Section 4: First Aid Measures. ... ', 'Section 5: Firefighting. ... ', 'Section 6: Spills, Leaks, Cleanup. ... ', 'Section 7: Handling and Storage.']