\s Character class for white space.
\S Character class for non white space.
\t Tab character.
- \u Uppercase next character.
+ \u Titlecase next character.
\U Uppercase till \E.
\v Character class for vertical white space.
\V Character class for non vertical white space.
A number of backslash sequences have to do with changing the character,
or characters following them. C<\l> will lowercase the character following
-it, while C<\u> will uppercase the character following it. (They perform
-similar functionality as the functions C<lcfirst> and C<ucfirst>).
+it, while C<\u> will uppercase (or, more accurately, titlecase) the
+character following it. (They perform similar functionality as the
+functions C<lcfirst> and C<ucfirst>).
To uppercase or lowercase several characters, one might want to use
C<\L> or C<\U>, which will lowercase/uppercase all characters following
(vertical white space), and the multi character sequence C<"\x0D\x0A">
(carriage return followed by a line feed, aka the network newline, or
the newline used in Windows text files). C<\R> is equivalent with
-C<(?>\x0D\x0A)|\v)>. Since C<\R> can match a more than one character,
+C<< (?>\x0D\x0A)|\v) >>. Since C<\R> can match a more than one character,
it cannot be put inside a bracketed character class; C</[\R]/> is an error.
C<\R> is introduced in perl 5.10.