Your second take is much better, much more indented, but try and keep things neat. Your closing brace in your foreach, for example, is strangely at the end of a line which is also sans-semicolon.

Anyway, to "derefence" something is to take a reference and use it to obtain a value. References are what make people exposed to C for the first time look all green and dizzy, but they're really not that bad, especially in Perl.

Here's a really, really brief introduction to references:

my @array      = qw[ 1 2 3 ];
my $array_ref  = \@array;      # Backslash makes a reference
my @array_copy = @$array_ref;  # @ de-references array reference

$array[2]       = 4;   # Modifies @array directly
print $array_ref->[2]; # Should be '4' now
$array_ref->[1] = 5;   # Modifies @array by reference
print $array[1];       # Should be '5'
$array_copy[1]  = 6;   # Modifies @array_copy, not @array
print $array[1];       # Still '5'
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For a much more detailed document, check out perlref.

Fortunately, or unfortunately depending on your opinion, Perl will automagically dereference for you in certain circumstances. Where $foo->{bar} is actually an "ARRAY" reference, you should really sub-address that as $foo->{bar}->[1] and not $foo->{bar}[1], but either should work.