For configuration, I have currently set it up to be a server port attribute rather than an explicit configuration option. My view is that it is unclear that globally enabling transparency is a good idea and may break reasonable deployment scenarios. I have also split transparency in to two parts, inbound (client side) and outbound (server side). The implementation is already structured that way and there are use cases for at least one of the intermediate states.
To configuration transparency, the server port attribute is set to "<", ">", or "=" instead of "C", "X", "T", or "D".
"<" : Outbound (server side) transparency. The origin server sees the client IP address but the client sees an explicit proxy.
">": Inbound (client side) transparency. The client does not see the proxy, but the origin server sees an IP address assigned to ATS. This is a deployment that one might see deployed, to hide internal addresses on a corporate network.
"=": Full transparency, both client and origin server see the connection as a direct one.