Topic awaiting preservation: php/ http-header redirect with time

i know there is the possibility to redirect to a page after lets say 3 seconds with php-headers, but i didnt find it on the manual and i dont want to read through w3c's http specification.

so how is the header to redirect to a location after 3 seconds?

<?php

header("Refresh: 3; URL=/index.php\n\n");
echo " "; // NN4 requires that we output something...
exit();

?>

thanks a lot man!