abc
efg
...
START
lines not to be extracted
END

START
lines to be extracted
END

START
lines not to be extracted
END

...

##</code><code>##

 
my $count = 0;
 11 while (<$fh_r>) {
 12   if (/START/ .. /END/) {
 13     $count++ if /START/;
 14     print if ($count == 2);
 15   }
 16 }