// pre-load the rollover images
		home_h= new Image();
		home_h.src = "../_images/nav/home_icon_h.gif";
		news_h= new Image();
		news_h.src = "../_images/nav/news_icon_h.gif";
		diary_h= new Image();
		diary_h.src = "../_images/nav/diary_icon_h.gif";
		resource_h= new Image();
		resource_h.src = "../_images/nav/resource_library_icon_h.gif";
		discussion_h= new Image();
		discussion_h.src = "../_images/nav/discussion_forums_icon_h.gif.gif";
		users_h= new Image();
		users_h.src = "../_images/nav/user_search_icon_h.gif";
		messages_h= new Image();
		messages_h.src = "../_images/nav/messages_icon_h.gif";
		advice_h= new Image();
		advice_h.src = "../_images/nav/advice_centre_icon_h.gif";
		profile_h= new Image();
		profile_h.src = "../_images/nav/your_profile_icon_h.gif";
		
		helpURL = "";
		helpWin = null;
		// closes the help window if open
		function checkHelpWin() {
			if ((helpWin != null)&&(!helpWin.closed)) {
				helpWin.close();
				helpWin = null;
			}
		}
		
		// open the help window in a bit
		function openHelp(url) {
			helpURL = url;
			checkHelpWin();
			setTimeout("launchHelp()",100);
		}
		
		// actually open the help window now
		function launchHelp() {
			helpWin = window.open(helpURL,"help","width=700,height=350,left=50,top=100,toolbar=no,menubar=no,status=no,scrollbars=yes,resizable=yes,fullscreen=no");
		}

		contract = new Image();
		contract.src = "images/contract.gif";
		expand = new Image();
		expand.src = "images/expand.gif";
		
		function showHide(row_id, img_id) {
			// show or hide table rows that start with a specific id
			rows = document.body.getElementsByTagName("tr"); 
			for (row in rows) {
				if (row.indexOf(row_id) == 0) { 
					if (document.all[row].style.display != "block") { 
						document.all[row].style.display = "block";
						document.images[img_id].src = contract.src;
					} else {
						document.all[row].style.display = "none";
						document.images[img_id].src = expand.src;
					}
				}
			}
		}