+.B "\-4, \-\-ipv4"
+Use only IPv4 addresses. The server will resolve names only to IPv4
+addresses, and not attempt to create IPv6 sockets.
+.TP
+.B "\-6, \-\-ipv6"
+Use only IPv6 addresses. The server will resolve names only to IPv6
+addresses, and not attempt to create IPv4 sockets. Note that v6-mapped
+IPv4 addresses won't work either.
+.TP