meaning in any future version of Perl; such names may therefore be
used safely in programs. C<$^_> itself, however, I<is> reserved.
-Perl identifiers that begin with digits, control characters, or
-punctuation characters are exempt from the effects of the C<package>
-declaration and are always forced to be in package C<main>; they are
-also exempt from C<strict 'vars'> errors. A few other names are also
-exempt in these ways:
+Perl identifiers that consist of all digits, or begin with control
+characters, or are a single punctuation character, are exempt from the
+effects of the C<package> declaration and are always forced to be in
+package C<main>; they are also exempt from C<strict 'vars'> errors. A
+few other names are also exempt in these ways:
ENV STDIN
INC STDOUT