// JavaScript Document
function checkMandatory ()
{
		var error_string = "";
// check the text field
		if (window.document.sub_search.searchcolltext.value=="")
		{
			error_string += "Please enter a keyword to search.\n";
		}
// make sure at leaast one check box is selected
	var check_select = "no";
	for (var loop = 0; loop < window.document.sub_search.Group.length; loop++)
	{
		if (window.document.sub_search.Group[loop].checked==true)
		{
			check_select = "yes";
		}
	}
	if ((check_select == "no") && (error_string ==""))
	{
		error_string += "Please select at least one collection to search.\n";
	}
	if ((check_select == "no") && (error_string =="Please enter a keyword to search.\n"))
	{
		error_string = "Please enter a keyword and select at least one collection to search.\n";
	}
	if (error_string =="")
	{
		return true;
	} else {
		error_string = error_string;
		alert (error_string);
		return false;
	}
}