(b) If a subject or medium of payment of a contract, security or instrument is the ECU, the euro will be a commercially reasonable substitute and substantial equivalent that may be either: (i) used in determining the value of the ECU; or (ii) tendered, in each case at the conversion rate specified in, and otherwise calculated in accordance with, the regulations adopted by the Council of the European Union.
(c) Performance of any of the obligations described in paragraph (a) or (b) of this subdivision may be made in the currency or currencies originally designated in such contract, security or instrument (so long as such currency or currencies remain legal tender) or in euro, but not in any other currency, whether or not such other currency (i) has been substituted or replaced by the euro or (ii) is a currency that is considered a denomination of the euro and has a fixed conversion rate with respect to the euro. 2. None of: (a) the introduction of the euro; (b) the tendering of euros in connection with any obligation in compliance with paragraph (a) or (b) of subdivision one of this section; (c) the determining of the value of any obligation in compliance with paragraph (a) or (b) of subdivision one of this section; or (d) the calculating or determining of the subject or medium of payment of a contract, security or instrument with reference to interest rate or other basis has been substituted or replaced due to the introduction of the euro and that is a commercially reasonable substitute and substantial equivalent, shall either have the effect of discharging or excusing performance under any contract, security or instrument, or give a party the right to unilaterally alter or terminate any contract, security or instrument.