See L<perlfunc/vec> for information on how to manipulate individual bits
in a bit vector.
+=head2 Version tuples
+
+A version number of the form C<v1.2.3.4> is parsed as a dual-valued literal.
+It has the string value of C<"\x{1}\x{2}\x{3}\x{4}"> (i.e., a utf8 string)
+and a numeric value of C<1 + 2/1000 + 3/1000000 + 4/1000000000>. This is
+useful for representing and comparing version numbers.
+
+Version tuples are accepted by both C<require> and C<use>. The C<$^V> variable
+contains the running Perl interpreter's version in this format.
+See L<perlvar/$^V>.
+
=head2 Integer Arithmetic
By default, Perl assumes that it must do most of its arithmetic in
The non-standard modules SSLeay::BN and Math::Pari provide
equivalent functionality (and much more) with a substantial
performance savings.
+
+=cut