If you are looking for comments, how to create a multi-dimensional structure, the following might give you a start. With all these nested structures, Data::Dumper is an invaluable tool to inspect them.

use strict;
use warnings;
use Data::Dumper;

my %metals;
$metals{'LB'}{'LENGTH_RANGES'} = [ 0, 10 ];
$metals{'LB'}{'WIDTH_RANGES'} = [ 0, 1.080 ];
$metals{'LB'}{'EM_POLY'} = "(-0.665364 + (9.6216 * W))*(10/L)";

print Dumper \%metals;
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