Why would you think that? Test it out.

#/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my $line = "FooBarBaz";
my @array = unpack('A3A3A3',$line);
print Dumper \@array;
[download]

$VAR1 = [
          'Foo',
          'Bar',
          'Baz'
        ];
[download]

As to your signature: I would suggest reading something I wrote earlier.