This property is used to tell the control which type of authorization to perform when connecting to the proxy.
authBasic(0), authDigest(1), authProprietary(2), authNone(3), authNtlm(4), authNegotiate(5)
ProxyAuthScheme should be set to authNone (3) when no authentication is expected.
If ProxyAuthScheme is set to authDigest (1), digest authentication will be attempted instead.
If ProxyAuthScheme is set to authProprietary (2), then the authorization token will not be generated by the control. Look at the configuration file for the control being used to find more information about manually setting this token.
If ProxyAuthScheme is set to authNtlm (4), NTLM authentication will be used.