5.16 also updates the core to support Unicode 6.1. On May 18, 2013, Perl 5.18 was released. Notable new features include the new dtrace hooks, lexical subs, more CORE:: subs, overhaul of the hash for security reasons, support for Unicode 6.2. On May 27, 2014, Perl 5.20 was released. Notable new features include subroutine signatures, hash slices/new slice syntax, postfix dereferencing (experimental), Unicode 6.3, using consistent random number generator. Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement. In particular, this phrase describes a style of development that embraces the use of the CPAN, takes advantage of recent developments in the language, and is rigorous about creating high quality code. While the book "Modern Perl" may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization have taken up the cause. In late 2012 and 2013, several projects for alternative implementations for Perl 5 started: Perl5 in Perl6 by the Rakudo Perl team, by Stevan Little and friends, by the Perl11 team under Reini Urban, by , and , a Kickstarter project led by Will Braswell and affiliated with the Perll11 project. 2020 onward In June 2020, Perl 7 was announced as the successor to Perl 5. Perl 7 was to initially be based on Perl 5.32 with a release expected in first half of 2021, and release candidates sooner. This plan was revised in May 2021, without any release timeframe or version of Perl 5 for use as a baseline specified. When Perl 7 is released, Perl 5 will go into long term maintenance. Supported Perl 5 versions however will continue to get important security and bug fixes. Symbols Camel Programming Perl, published by O'Reilly Media, features a picture of a dromedary camel on the cover and is commonly called the "Camel Book". This image has become an unofficial symbol of Perl as well as a general hacker emblem, appearing on T-shirts and other clothing items. O'Reilly owns the image as a trademark but licenses it for non-commercial use, requiring only an acknowledgement and a link to www.perl.com. Licensing for commercial use is decided on a case-by-case basis. O'Reilly also provides "Programming Republic of Perl" logos for non-commercial sites and "Powered by Perl" buttons for any site that uses Perl. Onion The Perl Foundation owns an alternative symbol, an onion, which it licenses to its subsidiaries,