<cats>
    <item>...</item>
    <item>...</item>
    ...
</cats>

<cats>
    <cat>...</cat>
    <cat>...</cat>
    ...
</cats>

class XmlIO {
...

public:
...
	template <class T> XmlIO operator()(const char *tag, const char *itemtag, T& var);

template <class T>
void Xmlize(XmlIO xml, const char* itemtag, T& var)
{
	var.Xmlize(xml);
}

...

template <class T> XmlIO XmlIO::operator()(const char *tag, const char *itemtag, T& var) {
	XmlIO n(*this, tag);
	Xmlize(n, itemtag, var);
	return *this;
}

...

template<class T>
void Xmlize(XmlIO xml, const char* itemtag, Vector<T>& data)
{
	XmlizeContainer(xml, itemtag, data);
}

...

template<class T>
void Xmlize(XmlIO xml, const char* itemtag, Array<T>& data)
{
	XmlizeContainer(xml, itemtag, data);
}

xml("cats", cats);

xml("cats", "cat", cats);