=over 10
-=item (?#text)
+=item C<(?#text)>
A comment. The text is ignored. If the C</x> switch is used to enable
whitespace formatting, a simple C<#> will suffice.
-=item (?:regexp)
+=item C<(?:regexp)>
This groups things like "()" but doesn't make backreferences like "()" does. So
but doesn't spit out extra fields.
-=item (?=regexp)
+=item C<(?=regexp)>
A zero-width positive lookahead assertion. For example, C</\w+(?=\t)/>
matches a word followed by a tab, without including the tab in C<$&>.
-=item (?!regexp)
+=item C<(?!regexp)>
A zero-width negative lookahead assertion. For example C</foo(?!bar)/>
matches any occurrence of "foo" that isn't followed by "bar". Note
For lookbehind see below.
-=item (?<=regexp)
+=item C<(?<=regexp)>
A zero-width positive lookbehind assertion. For example, C</(?=\t)\w+/>
matches a word following a tab, without including the tab in C<$&>.
Works only for fixed-width lookbehind.
-=item (?<!regexp)
+=item C<(?<!regexp)>
A zero-width negative lookbehind assertion. For example C</(?<!bar)foo/>
matches any occurrence of "foo" that isn't following "bar".
Works only for fixed-width lookbehind.
-=item (?{ code })
+=item C<(?{ code })>
Experimental "evaluate any Perl code" zero-width assertion. Always
-succeeds. Currently the quoting rules are somewhat convoluted, as is the
-determination where the C<code> ends.
-
+succeeds. C<code> is not interpolated. Currently the rules to
+determine where the C<code> ends are somewhat convoluted.
=item C<(?E<gt>regexp)>
effect may be achieved by negative lookahead, as in C<[^()]+ (?! [^()] )>.
This was only 4 times slower on a string with 1000000 C<a>s.
-=item (?(condition)yes-regexp|no-regexp)
+=item C<(?(condition)yes-regexp|no-regexp)>
-=item (?(condition)yes-regexp)
+=item C<(?(condition)yes-regexp)>
Conditional expression. C<(condition)> should be either an integer in
parentheses (which is valid if the corresponding pair of parentheses
matches a chunk of non-parentheses, possibly included in parentheses
themselves.
-=item (?imsx)
+=item C<(?imsx)>
One or more embedded pattern-match modifiers. This is particularly
useful for patterns that are specified in a table somewhere, some of