+ # without explicit or implicit use feature 'unicode_strings'
+ my $x = "\xDF"; # LATIN SMALL LETTER SHARP S
+ $x =~ /ss/i; # won't match
+ my $y = uc($x); # won't convert
+ utf8::upgrade($x);
+ $x =~ /ss/i; # matches
+ my $z = uc($x); # converts to "SS"
+
+B<Note that this function does not handle arbitrary encodings>;
+use L<Encode> instead.
+
+=item * C<$success = utf8::downgrade($string[, $fail_ok])>
+
+(Since Perl v5.8.0)
+Converts in-place the internal representation of the string from UTF-8 to the
+equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The
+logical character sequence itself is unchanged. If I<$string> is already
+stored as native 8 bit, then this is a no-op. Can be used to make sure that
+the UTF-8 flag is off, e.g. when you want to make sure that the substr() or
+length() function works with the usually faster byte algorithm.
+
+Fails if the original UTF-8 sequence cannot be represented in the