use warnings;
use strict;
my $count = 0;
while (<DATA>) {
	if (/START/ .. /END/) {
		$count++ if /START/;
		print if ($count == 2);
	}
}
__DATA__
abc
efg
...
START
lines NOT to be extracted 1
END
START
lines to be extracted
END
START
lines NOT to be extracted 2
END
START
lines NOT to be extracted 3
END

##</code><code>##

START
lines to be extracted
END

##</code><code>##

lines to be extracted
lines NOT to be extracted 3