On March 31st, 2021, 50ETF closed at 3.527 Yuan, the settlement price of 50ETF April call (K = 3.6) is 0.0362 Yuan, while the settlement price of 50ETF April put (K = 3.5) is 0.0644 Yuan. On April 1st, Mr. Huang sold one 50ETF April call (K = 3.6) contract at a price of 0.0408 Yuan, and sold one 50ETF April put (K = 3.5) contract at a price of 0.0515 Yuan. At that moment, 50ETF stood at 3.541 Yuan. Each option contract concerns 10,000 shares.

(i) Explain the difffference between the initial margin and maintenance margin.

(ii) Calculate the initial margin for the call position.

(iii) Calculate the initial margin for the put position.