Today I'm editing the Modern Perl book and the Rakudo Perl 6 book. The human brain is wonderful at seeing patterns, even unintentional and nonexistent. I saw the word "Perl" in both book titles and wondered at the confusion.
Why is Modern Perl clearly about Perl 5? Why does Rakudo Perl 6 need a version number? As Patrick wrote a couple of weeks ago:
Granted, Modern Perl is my book, published by my company, and I have the final say on anything on or in the book—but can anyone think of a good reason not to rename it to Modern Perl 5?
(Note that Andy Lester suggested saying "Perl 5" when you mean "Perl 5" almost a year ago, and he was right.)