Paragraph 15

to vary the rate of interest specified in paragraph 5 above for determining the amount of the prize fund;

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

to vary the provisions of paragraph 7 above insofar as they relate to the eligibility of a Bond for inclusion in a draw after the death of the registered holder;

to declare any Bonds purchased on or before a date specified F3... to be ineligible for further draws.