2.2.1.6.1.2.2 Proxy-Connection header

The Proxy-Connection element contains a string value that specifies whether the connection is to be kept open after the request has been sent. If the value indicates that the connection can be kept open, the HTTP 1.1 proxy will accept subsequent requests that can be executed against the server URI.

 Proxy-Connection= Proxy-Connection: string

By default, the client emits the string ""Keep-Alive"" as the value for this header.<7>