wdisp/add_client_protocol_header is a SAP Parameter attribute which is used to control Send header field client-protocol to application server information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter determines whether the protocol between the browser and
the Web Dispatcher (HTTP or HTTPS) is notified to the application
server.
This information is sent in the header field clientprotocol.
If there is a change in protocol in the Web Dispatcher, the application
server requires this information, to generate absolute URLs (it can get
the Web dispatcher host and port names from the header field Host).
See SAP Parameter Documentation for full SAP documentation for this profile parameter.