Opinion of the European Central Bank of 16 June 2000 at the request of the Council of the European Union pursuant to Article 123(5) of the Treaty establishing the European Community on proposals for three Council Regulations amending Regulation (EC) No 974/98 on the introduction of the euro, amending Regulation (EC) No 1103/97 on certain provisions relating to the introduction of the euro and amending Regulation (EC) No 2866/98 on the conversion rates between the euro and the currencies of the Member States