The Unix System V IPC (C<msg*(), sem*(), shm*()>) is not available
even on all Unix platforms.
-Do not use either the bare result of C<pack("N", 10, 20, 30, 40)>
-or bare v-strings (such as C<v10.20.30.40>) or to represent
-IPv4 addresses: both forms just pack the four bytes into network order.
-That this would be equal to the C language C<in_addr> struct (which is
-what the socket code internally uses) is not guaranteed. To be
-portable use the routines of the Socket extension, such as
-C<inet_aton()>, C<inet_ntoa()>, and C<sockaddr_in()>.
+Do not use either the bare result of C<pack("N", 10, 20, 30, 40)> or
+bare v-strings (such as C<v10.20.30.40>) to represent IPv4 addresses:
+both forms just pack the four bytes into network order. That this
+would be equal to the C language C<in_addr> struct (which is what the
+socket code internally uses) is not guaranteed. To be portable use
+the routines of the Socket extension, such as C<inet_aton()>,
+C<inet_ntoa()>, and C<sockaddr_in()>.
The rule of thumb for portable code is: Do it all in portable Perl, or
use a module (that may internally implement it with platform-specific