The remote_socket argument, in its end (well... after the port), can also contain a "/" followed by a unique identifier. This is especially useful if you want to create multiple persistent connections to the same transport://host:port combo.
Example:
<?php
$socket = stream_socket_client('tcp://mysql.example.com:3306/root', $errorno, $errorstr, $timeout, STREAM_CLIENT_CONNECT | STREAM_CLIENT_PERSISTENT);
?>
Note that while (p)fsockopen() follows a similar scheme, it doesn't have this particular feature.
