function toggleVis(theid) {
	// toggles rendering of an element by ID
	// if the given id is off, turn it on, and vice versa
	if(document.getElementById(theid).style.display == 'block') {
		document.getElementById(theid).style.display = 'none';
	} else {
		document.getElementById(theid).style.display = 'block';
	}
};
function selectToggle(prefix, theSelect, value) {
	// loop thru option values
	for(i=0; i<theSelect.options.length; i++) {
		// hide all related blocks
		theID = prefix + theSelect.options[i].value;
		hideVis(theID);
	}
	// show the selected value
	showVis(prefix + value);
};
function showVis(theid) {
	// simply shows something
	if(theid == "") {
		return;
	} else {
		if(document.getElementById(theid)) document.getElementById(theid).style.display = 'block';
	}
};
function hideVis(theid) {
	// simply hides something
	if(theid == "") {
		return;
	} else {
		if(document.getElementById(theid)) document.getElementById(theid).style.display = 'none';
	}
};