You can use %server[key] to add any of the special PHP <a href="http://www.php.net/reserved.variables#reserved.variables.server">$_SERVER</a> variables, %session[key] to add any of the special PHP <a href="http://www.php.net/reserved.variables#reserved.variables.session">$_SESSION</a> variables and %get[key] to create prefilled forms from the <a href="http://www.php.net/reserved.variables#reserved.variables.get">URL</a>. %cookie, %request and %post also work with their respective PHP variables. For example %server[HTTP_USER_AGENT], %session[id], or %get[q].