//  "Internal" function to return the decoded value of a cookie
function getCookieVal (offset)
{
	var endstr = document.cookie.indexOf (";", offset);
	if (endstr == -1)
	endstr = document.cookie.length;
	return unescape(document.cookie.substring(offset, endstr));
}

//  Function to return the value of the cookie specified by "name".
//    name -    String object containing the cookie name.
//    returns - String object containing the cookie value,
//              or null if the cookie does not exist.
//
function GetCookie (name)
{
	var arg = name + "=";
	var alen = arg.length;
	var clen = document.cookie.length;
	var i = 0;
	while (i < clen)
	{
		var j = i + alen;
		if (document.cookie.substring(i, j) == arg)
			return getCookieVal (j);
		i = document.cookie.indexOf(" ", i) + 1;
		if (i == 0)
			break; 
	}
	return null;
}

//  Function to create or update a cookie.
//    name - String object containing the cookie name.
//    value - String object containing the cookie value.  May contain
//         any valid string characters.
//    [expires] - Date object containing the expiration data of the cookie.  If
//         omitted or null, expires the cookie at the end of the current session.
//    [path] - String object indicating the path for which the cookie is valid.
//         If omitted or null, uses the path of the calling document.
//    [domain] - String object indicating the domain for which the cookie is
//         valid. If omitted or null, uses the domain of the calling document.
//    [secure] - Boolean (true/false) value indicating whether cookie
//         transmission requires a secure channel (HTTPS).  
//
//  The first two parameters are required.  The others, if supplied, must
//  be passed in the order listed above.  To omit an unused optional field,
//  use null as a place holder.  For example, to call SetCookie using name,
//  value and path, you would code:
//
//      SetCookie ("myCookieName", "myCookieValue", null, "/");
//
//  Note that trailing omitted parameters do not require a placeholder.
//
//  To set a secure cookie for path "/myPath", that expires after the
//  current session, you might code:
//
//      SetCookie (myCookieVar, cookieValueVar, null, "/myPath", null, true);
//
function SetCookie (name,value,expires,path,domain,secure)
{
	document.cookie = name + "=" + escape (value) +
	((expires) ? "; expires=" + expires.toGMTString() : "") +
	((path) ? "; path=" + path : "") +
	((domain) ? "; domain=" + domain : "") +
	((secure) ? "; secure" : "");
}

//  Function to delete a cookie. (Sets expiration date to start of epoch)
//    name -   String object containing the cookie name
//    path -   String object containing the path of the cookie to delete.
//             This MUST be the same as the path used to create the cookie, or
//             null/omitted if no path was specified when creating the cookie.
//    domain - String object containing the domain of the cookie to delete.
//             This MUST be the same as the domain used to create the cookie, or
//             null/omitted if no domain was specified when creating the cookie.
//
function DeleteCookie (name,path,domain)
{
	if (GetCookie(name))
	{
		document.cookie = name + "=" +
		((path) ? "; path=" + path : "") +
		((domain) ? "; domain=" + domain : "") +
		"; expires=Thu, 01-Jan-70 00:00:01 GMT";
	}
}