#! perl
use strict;
use warnings;

my ($found, @lines);

while (<DATA>)
{
    if (my $flag = /START/ .. /END/)
    {
        $found = /def/ unless $found;
        push @lines, $_;

        if ($flag =~ /E0$/)
        {
            if ($found)
            {
                $found = 0;
            }
            else
            {
                print for @lines;
            }

            @lines = ();
        }
    }
    else
    {
        print;
    }
}

__DATA__
Source Data
START
abc
def
ghi
END
START
xyz
abc
END

##</code><code>##

14:22 >perl 1646_SoPW.pl
Source Data
START
xyz
abc
END

14:22 >