having a cookie with sub-keys


This is from ASP.NET Cookies Overviewe

example

HttpCookie cookie = HttpContext.Current.Request.Cookies[site.cookieName];
if (cookie == null)
{
cookie = new HttpCookie(site.cookieName);
cookie.Values["MId"] = Guid.NewGuid().ToString();
cookie.Values["IsMId"] = true.ToString();
cookie.Expires = DateTime.Today.AddYears(30);

Response.Cookies.Add(cookie);
}