The ProtocolVersion property sets or returns the current
HTTP version number. It is used to determine how requests are
submitted to the server, as well as what header fields are required.
The default value for this property is "1.0", and should be changed
before any connection attempt is made by the client.
Note that setting the property value to "0.9" tells the control to
use the preliminary protocol specification, circa 1994. This version
of the protocol only supported a basic version of the GET command,
and did not have any provisions for features such as user
authentication.