The provisions of Titles I, II, III and IV of this book may not be modified by agreement, except those which give the parties a simple option and which are contained in the last paragraph of I and II of article L. 111-10 and in Articles L. 112-1, L. 112-5, L. 112-6, L. 113-10, L. 121-5 to L. 121-8, L. 121-12, L. 121-14, L. 122-1, L. 122-2, L. 122-6, L. 124-1, L. 124-2, L. 127-6, L. 132-1, L. 132-10, L. 132-15 and L. 132-19.