function dynamicSelect(id1, id2)
{
	// Browser and feature tests to see if there is enough W3C DOM support
	var agt = navigator.userAgent.toLowerCase();
	var is_ie = ((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1));
	var is_mac = (agt.indexOf("mac") != -1);
	if (!(is_ie && is_mac)
			&& document.getElementById && document.getElementsByTagName)
	{
		// Obtain references to both select boxes
		var sel1 = document.getElementById(id1);
		var sel2 = document.getElementById(id2);
		// Clone the dynamic select box into a global variable
		clone = sel2.cloneNode(true);
		// Obtain references to all cloned options in a global variable
		clonedOptions = clone.getElementsByTagName("option");
		// Onload init: call a generic function
		// to display the related options in the dynamic select box
		refreshDynamicSelectOptions(sel1, sel2, clonedOptions);
		// Onchange of the main select box: call a generic function
		// to display the related options in the dynamic select box
		sel1.onchange = function() {
			refreshDynamicSelectOptions(sel1, sel2, clonedOptions);
		};
	}
}

function refreshDynamicSelectOptions(sel1, sel2, clonedOptions)
{
	var opt;
	var optSelected = null;
	// Delete all options of the dynamic select box
	while (sel2.options.length)
	{
		sel2.remove(0);
	}
	// Create regular expression objects for "select"
	// and the value of the selected option of the main select box
	// as class names
	var pattern1 = /( |^)(select)( |$)/;
	var pattern2 = new RegExp(sel1.options[sel1.selectedIndex].value);
/*	var pattern2 = new RegExp("( |^)(" + sel1.options[sel1.selectedIndex].value + ")( |$)"); */
	// Iterate through all cloned options
	for (var i = 0; i < clonedOptions.length; i++)
	{
		// If the classname of a cloned option
		// either equals "select"
		// or equals the value of the selected option of the main select box
		if (clonedOptions[i].className.match(pattern1)
				|| clonedOptions[i].className.match(pattern2))
		{
			// Clone the option from the hidden option pool
			// and append it to the dynamic select box
			opt = clonedOptions[i].cloneNode(true);
			sel2.appendChild(opt);
			optSelected = clonedOptions[i].getAttribute("selected");
			if(optSelected)
				optSelected = opt;
		}
	}
}