struct MyClass {
	MyClass(int data) : data(data) {};
	int data;
	void Serialize(Stream& stream) 	{stream % data;}
};

struct MyClassA : public MyClass {
	MyClassA(int dataA) : dataA(dataA) {data = dataA*2;};
	int dataA;
	void Serialize(Stream& stream) 	{stream % dataA; MyClass::Serialize(stream);}
}

struct MyClassList {
	Array<MyClass> elems;
	void Serialize(Stream& stream) 	{stream % elems;}
};

...
elems.Add(new MyClassA(12));
StoreToFile(elems, "myfile");