+\S2{using-cmdline-ipversion} \i\c{-4} and \i\c{-6}: specify an
+\i{Internet protocol version}
+
+The \c{-4} and \c{-6} options force PuTTY to use the older Internet
+protocol \i{IPv4} or the newer \i{IPv6}.
+
+These options are equivalent to selecting your preferred Internet
+protocol version as \q{IPv4} or \q{IPv6} in the Connection panel of
+the PuTTY configuration box (see \k{config-address-family}).
+