use strict;
use Data::Dumper;

my %hash;
$hash{Company_A}{ Identifier_1 } = ["a", "b"]; 
$hash{Company_A}{ Identifier_2 } = ["b", "g"];                              
$hash{Company_A}{ Identifier_3 } = "c"; 

$hash{Company_B}{ Identifier_1 } = "a"; 
$hash{Company_B}{ Identifier_2 } = "g"; 
$hash{Company_B}{ Identifier_3 } = "x"; 

print Dumper(%hash);

traverse( 0, \%hash );

sub traverse {
  my $level = shift;
  my $ref = shift;
  if( ref($ref) =~ /HASH/ ) {
    print "\n";
    for my $key (keys %$ref) {
      print "\t" x $level, $key;
      traverse( $level+1, $$ref{$key} );
    }
  } elsif( ref($ref) =~ /ARRAY/ ) {
    print "\n";
    for (@$ref) {
      print "\t" x $level;
      traverse( $level+1, $_ );
    }
  } else {
    print "\t" x $level, $ref, "\n";
  }
}