Don't count on a specific environment variable existing in C<%ENV>.
Don't count on C<%ENV> entries being case-sensitive, or even
-case-preserving.
+case-preserving. Don't try to clear %ENV by saying C<%ENV = ();>, or,
+if you really have to, make it conditional on C<$^O ne 'VMS'> since in
+VMS the C<%ENV> table is much more than a per-process key-value string
+table.
Don't count on signals or C<%SIG> for anything.
=item *
The Cygwin environment for Win32; F<README.cygwin> (installed
-as L<perlcygwin>), http://sources.redhat.com/cygwin/
+as L<perlcygwin>), http://www.cygwin.com/
=item *
precompiled binary and source code form from http://www.novell.com/
as well as from CPAN.
-=item
+=item *
Plan 9, F<README.plan9>