foreach my $ext (keys %{ $Registry->{"Classes/"} }) {
    next unless substr($ext, 0, 1) eq '.';

    my $RegHash = $Registry->{"Classes/$ext"};

    if (not exists $RegHash->{'/'}) {
       warn "Unable to recognise association list for $ext\n";
       next;
    }

    my $class = $RegHash->{'/'};
    print "$ext is a $class\n";
}