use strict;
use warnings;
use Data::Dump;

my @window;

push @window, scalar <DATA> for 1..5; 				    # init

while (my $line = <DATA>) {
    push @window, $line;
    chomp @window;
    
    if( $window[3] =~ m/[^\d]+\d+/ ){
         dd \@window;
    }

    shift @window;
}



__END__
alpha
beta
something
a07607
b-alpha
b-beta
b-something
b-something else
c-alpha
c-beta
c-somethin
a9706
d-alpha
d-beta
d-something
d-something else

##</code><code>##

["alpha", "beta", "something", "a07607", "b-alpha", "b-beta"]
["c-alpha", "c-beta", "c-somethin", "a9706", "d-alpha", "d-beta"]

##</code><code>##

use strict;
use warnings;
use Data::Dump;

my @window;

while (my $line = <DATA>) {
    push @window, $line;
    next if @window < 6;                # init
    
    if( $window[3] =~ m/[^\d]+\d+/ ){
        dd \@window;
    }

    shift @window;
}