substituted but only skipped. The full list of RE-special chars is
C<\>, C<.>, C<^>, C<$>, C<@>, C<A>, C<G>, C<Z>, C<d>, C<D>, C<w>, C<W>,
C<s>, C<S>, C<b>, C<B>, C<p>, C<P>, C<X>, C<C>, C<+>, C<*>, C<?>, C<|>,
-C<(>, C<)>, C<->, C<n>, C<r>, C<t>, C<f>, C<e>, C<a>, C<x>, C<c>, C<z>,
-digits (C<0> to C<9>), C<[>, C<{>, C<]>, C<}>, whitespaces (SPACE, TAB,
-LF, CR, FF, and VT in addition), and C<#>.
+C<(>, C<)>, C<->, C<N>, C<n>, C<r>, C<t>, C<f>, C<e>, C<a>, C<x>, C<c>,
+C<z>, digits (C<0> to C<9>), C<[>, C<{>, C<]>, C<}>, whitespaces
+(SPACE, TAB, LF, CR, FF, and VT in addition), and C<#>.
As C<\c> is skipped at this step, C<@> of C<\c@> in RE is possibly
treated as an array symbol (for example C<@foo>),
even though the same text in C<qq//> gives interpolation of C<\c@>.
-Note that C<\N{name}> is interpolated at this step.
Moreover, inside C<(?{BLOCK})>, C<(?# comment )>, and
a C<#>-comment in a C<//x>-regular expression, no processing is