When connection to a remote server is requested through
a proxy server, this function specifies the proxy's
port number for connection purposes.
The usual values for web proxies
are 80, 8000 or 8080.
The usual value for Socks 4 and
Socks 5 servers is 1080.
When a Relay proxy is used,
there is no usual value since a Relay
can listen on any port.
Please contact your administrator to obtain the proper
value for this function.