%brain = ( programming => { 'things to buy' => { 'doohickey' => undef, }, # ..., }, things_to_buy => {'milk' => '1 gallon', 'eggs' => {'amount' => 'dozen', 'color' => 'brown', 'size' => 'Large grade A' } 'doohickey' => undef }, doohickey => (\$brain{programming}, \$brain{things_to_buy}), etc... # ..., );