+XXX New core language features go here. Summarise user-visible core language
+enhancements. Particularly prominent performance optimisations could go
+here, but most should go in the L</Performance Enhancements> section.
+
+[ List each enhancement as a =head2 entry ]
+
+=head2 Improved ability to mix locales and Unicode, including UTF-8 locales
+
+An optional parameter has been added to C<use locale>
+
+ use locale ':not_characters';
+
+which tells Perl to use all but the C<LC_CTYPE> and C<LC_COLLATE>
+portions of the current locale. Instead, the character set is assumed
+to be Unicode. This allows locales and Unicode to be seamlessly mixed,
+including the increasingly frequent UTF-8 locales. When using this
+hybrid form of locales, the C<:locale> layer to the L<open> pragma can
+be used to interface with the file system, and there are CPAN modules
+available for ARGV and environment variable conversions.
+
+Full details are in L<perllocale>.
+
+=head2 New function C<fc> and corresponding escape sequence C<\F> for Unicode foldcase
+
+Unicode foldcase is an extension to lowercase that gives better results
+when comparing two strings case-insensitively. It has long been used
+internally in regular expression C</i> matching. Now it is available
+explicitly through the new C<fc> function call (enabled by
+S<C<"use feature 'fc'">>, or C<use v5.16>, or explicitly callable via
+C<CORE::fc>) or through the new C<\F> sequence in double-quotish
+strings.
+
+Full details are in L<perlfunc/fc>.
+
+=head2 C<_> in subroutine prototypes
+
+The C<_> character in subroutine prototypes is now allowed before C<@> or
+C<%>.
+
+=head2 Supports (I<almost>) Unicode 6.1
+
+Besides the addition of whole new scripts, and new characters in
+existing scripts, this new version of Unicode, as always, makes some
+changes to existing characters. One change that may trip up some
+applications is that the General Category of two characters in the
+Latin-1 range, PILCROW SIGN and SECTION SIGN, has been changed from
+Other_Symbol to Other_Punctuation. The same change has been made for
+a character in each of Tibetan, Ethiopic, and Aegean.
+The code points U+3248..U+324F (CIRCLED NUMBER TEN ON BLACK SQUARE
+through CIRCLED NUMBER EIGHTY ON BLACK SQUARE) have had their General
+Category changed from Other_Symbol to Other_Numeric. The Line Break
+property has changes for Hebrew and Japanese; and as a consequence of
+other changes in 6.1, the Perl regular expression construct C<\X> now
+works differently for some characters in Thai and Lao.
+
+New aliases (synonyms) have been defined for many property values;
+these, along with the previously existing ones, are all cross indexed in
+L<perluniprops>.
+
+The return value of C<charnames::viacode()> is affected by other
+changes:
+
+ Code point Old Name New Name
+ U+000A LINE FEED (LF) LINE FEED
+ U+000C FORM FEED (FF) FORM FEED
+ U+000D CARRIAGE RETURN (CR) CARRIAGE RETURN
+ U+0085 NEXT LINE (NEL) NEXT LINE
+ U+008E SINGLE-SHIFT 2 SINGLE-SHIFT-2
+ U+008F SINGLE-SHIFT 3 SINGLE-SHIFT-3
+ U+0091 PRIVATE USE 1 PRIVATE USE-1
+ U+0092 PRIVATE USE 2 PRIVATE USE-2
+ U+2118 SCRIPT CAPITAL P WEIERSTRASS ELLIPTIC FUNCTION
+
+Perl will accept any of these names as input, but
+C<charnames::viacode()> now returns the new name of each pair. The
+change for U+2118 is considered by Unicode to be a correction, that is
+the original name was a mistake (but again, it will remain forever valid
+to use it to refer to U+2118). But most of these changes are the
+fallout of the mistake Unicode 6.0 made in naming a character used in
+Japanese cell phones to be "BELL", which conflicts with the long
+standing industry use of (and Unicode's recommendation to use) that name
+to mean the ASCII control character at U+0007. As a result, that name
+has been deprecated in Perl since v5.14; and any use of it will raise a
+warning message (unless turned off). The name "ALERT" is now the
+preferred name for this code point, with "BEL" being an acceptable short
+form. The name for the new cell phone character, at code point U+1F514,
+remains undefined in this version of Perl (hence we don't quite
+implement all of Unicode 6.1), but starting in v5.18, BELL will mean
+this character, and not U+0007.