HRESULT STDMETHODCALLTYPE get_Item( 
  VARIANT VarKey,    //the identifier fot the item to return
  VARIANT*pvar       //a pointer to the item that is returned
);
 You can use this method to get the a unique indentifer for items in the ClientCertificates, Cookies, Form, and QueryString collections.
IRequestDictionary, IReadCookie, IWriteCookie IRequest