function dynamicSelect(id1, id2) {
// Feature test to see if there is enough W3C DOM support
	if (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
		var clone = sel2.cloneNode(true);
// Obtain references to all cloned options 
		var 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) {
// 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)( |$)/;
	var pattern2 = new RegExp("( |^)(" + sel1.options[sel1.selectedIndex].value + ")( |$)");
// 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
			sel2.appendChild(clonedOptions[i].cloneNode(true));
		}
	}
}

function dynamicTotal(id1, id2) {
// Feature test to see if there is enough W3C DOM support
	if (document.getElementById && document.getElementsByTagName) {
// Obtain references to both select boxes
		var sel1 = document.getElementById(id1);
		var sel2 = document.getElementById(id2);
// Onchange obtain values of both and add together
		sel2.value += sel1.value;
	}
}