I don't really understand your context, but if you want to iterate through nested hashes, it is usually easier to use the values function, rather than the keys function. Just a short example on how easy it is:

use strict;
use warnings;
my %hash = (
    A => { F => 1, G => "3A", H => 5 },
    B => { F => 1, G => "3B", H => 5 },
    C => { F => 1, G => "3C", H => 5 },
    D => { F => 1, G => "3D", H => 5 },
    E => { F => 1, G => "3E", H => 5 },
);
print "$_->{G} " for (values %hash);
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which prints:

3A 3D 3C 3E 3B
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Or, if you want to go through the values of the inner hashes:

print join " ", map {values %{$_}, "-"} values %hash;
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Output:

5 1 3A - 5 1 3D - 5 1 3C - 5 1 3E - 5 1 3B -
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