#!/usr/bin/perl

use warnings;
use strict;

my %h = ('BAUM' => {'ID' => '12',
                    'TYPE' => 'Baum'},
         'AUTO' => {'ID' => '15',
                    'TYPE' => 'Auto'});

foreach my $i (keys(%h)) {
    my %h2 = %{$h{$i}};
    print "$h2{ID}_$h2{TYPE}.csv\n";
}