-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.
-
-Unicode has taken steps to make sure that this sort of mistake does not
-happen again. The Standard now includes all the generally accepted
-names and abbreviations for control characters, whereas previously it
-didn't (though there were recommended names for most of them, which Perl
-used). This means that most of those recommended names are now
-officially in the Standard. Unicode did not recommend names for the
-four code points listed above between U+008E and U+008F, and in
-standardizing them Unicode subtly changed the names that Perl had
-previously given them, by replacing the final blank in each name by a
-hyphen. Unicode also officially accepts names that Perl had deprecated,
-such as FILE SEPARATOR. Now the only deprecated name is BELL.
-Finally, Perl now uses the new official names instead of the old
-(now considered obsolete) names for the first four code points in the
-list above (the ones which have the parentheses in them).
-
-Now that the names have been placed in the Unicode standard, these kinds
-of changes should not happen again, though corrections, such as to
-U+2118, are still possible.
-
-Unicode also added some name abbreviations, which Perl now accepts:
-SP for SPACE;
-TAB for CHARACTER TABULATION;
-NEW LINE, END OF LINE, NL, and EOL for LINE FEED;
-LOCKING-SHIFT ONE for SHIFT OUT;
-LOCKING-SHIFT ZERO for SHIFT IN;
-and ZWNBSP for ZERO WIDTH NO-BREAK SPACE.
-
-More details on this version of Unicode are provided in
-L<http://www.unicode.org/versions/Unicode6.1.0/>.
-
-=head2 Added C<is_utf8_char_buf()>
-
-This function is designed to replace the deprecated L</is_utf8_char()>
-function. It includes an extra parameter to make sure it doesn't read
-past the end of the input buffer.
-
-=head1 Security