function c(tag)
{
	return document.createElement(tag);
}

function g(id)
{
	return document.getElementById(id);
}

function t(text)
{
	return document.createTextNode(text);
}

function add_filter()
{
	var a;
	var form;
	var p;
	var text;
	var select;
	var option;
	var i;
	var tmp;
	var input;
	var cr;

	p = g("add_filter_link");
	if( p )
	{
		p.innerHTML = "... AND";
	}

	form = g("search_form");
	cr = g("criteria");

	cr.appendChild( t("Search all ") );
	select = c("select");
	select.name = "did";
	for(i=0;i<descriptor_options.length;i++)
	{
		tmp = descriptor_options[i];
		option = c("option");
		option.value = tmp[0];
		option.innerHTML = tmp[1];
		select.appendChild(option);
	}
	cr.appendChild(select);

	cr.appendChild(c("br"));

	cr.appendChild(t("for "));
	select = c("select");
	select.name = "tid";
	option = c("option");
	option.value = "-1";
	option.innerHTML = "any field";
	select.appendChild(option);
	for(i=0;i<metadata_type_options.length;i++)
	{
		tmp = metadata_type_options[i];
		option = c("option");
		option.value = tmp[0];
		option.innerHTML = tmp[1];
		select.appendChild(option);
	}
	cr.appendChild(select);

	cr.appendChild(t(" matching "));

	select = c("select");
	select.name = "qua";
	option = c("option");
	option.value = "any";
	option.innerHTML = "any";
	select.appendChild(option);
	option = c("option");
	option.value = "all";
	option.innerHTML = "all";
	select.appendChild(option);
	cr.appendChild(select);

	cr.appendChild(t(" of the following words: "));

	cr.appendChild(c("br"));

	input = c("input");
	input.type = "text";
	input.name = "phr";
	input.size = "60";
	cr.appendChild(input);

	p = c("p")
	p.id = "add_filter_link";
	a = c("a")
	a.href = "javascript:add_filter()";
	a.innerHTML = "Add another filter";
	p.appendChild(a);
	cr.appendChild(p);
}