ID inconsistency among implementations

Hello,

I have found that different CORBA implementations generates different
element IDs. Suppose this example:

module test {
	union myUnion switch(long) {
		case 0 : string str;
		case 1 : wstring wstr;
		case 3 : struct ms {
			boolean test;
		} ms_;
		case 4 : enum me {xx1, xx2} me_;
	};
};

Now when I generate stubs with various implementations I get different
IDs for the struct "ms":

JacORB: IDL: test/ms:1.0
Sun JRE 1.5: IDL:test/ms:1.0
Sun JRE 1.6: IDL:test/myUnion/ms/ms:1.0

Does this mean if you want to use IR among implementation you need to
modify it with #prefix statements?

ps - are interface IDs used for anything else than IR?