$product[$x]{name}           is the name of product $x.
$product[$x]{opts}[$i]       is the option $i of product $x.

@product                     is the list of products.
map { $_->{name} } @product  is the list of product names.
@{$product[$x]{opts}}        is the list of options of product $x.

##</code><code>##

$product{$name}[$i]   is the option $i of product $name.

keys %product         is the list of product names.
@{$product{$name}}    is the list of options of product $name.