function over () { this . src = this . src . replace ( '_off' , '_on' ) ; }
function out () { this . src = this . src . replace ( '_on' , '_off' ) ; }
function initRollovers ( menuId )  {
	var menu = document . getElementById ( menuId ) ;
	var menuItems = Array () ;
	menuItems = menu . getElementsByTagName ( 'img' ) ;
	for ( i = 0 ; i < menuItems . length ; i ++ ) {
		menuItems [ i ] . onmouseover = over ;
		menuItems [ i ] . onmouseout  = out ;
	}
}