This enables setting the DSCP/Traffic Class field of IP/IPv6 packets
sent by a client. For example starting a client with -qosdscp 184
marks all outgoing traffic for expedited forwarding.

Implementation for Win32 is still a TODO, though. See
http://betelco.blogspot.com/2009/03/dscp-marking-under-windows-at.html
for an overview of the Win32 QoS API mess...