function url_param(p) {
	// Retrieve an url param specified by p=value
	var re = new RegExp( p + "=([^&]+)" );
	return document.location.href.match(re)[1];
}



function highlight_subtile() {
	// Retrieve the current page from the URL, but ignore the
	// path to this page.
	// First try and match .html files
	var re = new RegExp( "/([^/]*)\.html" );
	var matches = document.location.href.match(re);
	var page = "";
	
	if (matches) {
		page = matches[1];
	} 
	else {
		// If that fails look for page= in URL
		page = url_param("page");
	}
		
	// Now locate td to switch styles on by prefixing "td_"
	var td = document.getElementById( "td_" + page );
	if (td) {
		td.className = "thispage";
	}

}