Commission Regulation (EC) No 396/2004 of 2 March 2004 initiating an investigation concerning the possible circumvention of anti-dumping measures imposed by Council Regulation (EC) No 964/2003 on imports of certain tube or pipe fittings, of iron or steel, originating, inter alia, in the People's Republic of China by imports of certain tube or pipe fittings, of iron or steel, consigned from Indonesia, whether declared as originating in Indonesia or not and making such imports subject to registration