The XSP Response Logicsheet is responsible for providing access to the response to be transmitted to the user. The access available from an XSP page is quite limited. This logicsheet only provides access to setting response headers, although one can call the XSP!ResponseHelper methods directly to allow encoding of URLs.
This limited access (e.g. restriction of includes/forwarding) is because of the strict separation of concerns in Cocoon. Includes should be handled, e.g. with XML Includes, while redirects and forwarding should be handled within the Sitemap.