COMMISSION REGULATION (EC) No 3550/93 of 21 December 1993 amending Regulation (EEC) No 584/92 laying down detailed rules for the application to milk and milk products of the arrangements provided for in the Interim Agreements between the Community and the Republic of Poland, the Republic of Hungary and the Czech and Slovak Federal Republic, and amending Regulation (EC) No 3055/93 determining the quantity available for the first quarter of 1994 in the milk sector pursuant to the said Interim Agreements