use Data::Dumper;

undef $/;
my $data = <DATA>;
my @data = split 'HOUR\*', $data;
shift @data;
my (%struct, @order);
for my $bit (@data) {
    my ($model) = $bit =~ m/MODEL\*([^:]+)/;
    push @order, $model;
    my ($hour)  = $bit =~ m/^(\d\d)/;
    my @u       = $bit =~ m/^U:([^\n]+)/mg;
    my @l       = $bit =~ m/^L:([^\n]+)/mg;
    my @d       = $bit =~ m/^D:([^\n]+)/mg;
    $struct{$model} = { hour => $hour, u => \@u, l => \@l, d => \@d };
}
print Dumper \%struct;

for my $model( @order ) {
    print "$model\n";
    print 'U', "\t" x ( 1 + $struct{$model}->{hour} ), $_, "\n" for @{$struct{$model}->{u}};
    print 'L', "\t" x ( 1 + $struct{$model}->{hour} ), $_, "\n" for @{$struct{$model}->{l}};
    print 'D', "\t" x ( 1 + $struct{$model}->{hour} ), $_, "\n" for @{$struct{$model}->{d}};
}
__DATA__
HOUR*00:MODEL*123.12.100.11:
U:1:23
L:1:2
D:1:-

HOUR*00:MODEL*123.12.100.12:
U:1:86
L:1:-
D:1:24

HOUR*01:MODEL*11MT-AS5300:
U:8:-
L:8:10
D:8:32

U:9:2
L:9:5
D:9:-

HOUR*02:MODEL*132.21.001.21:
U:1:6
L:1:8
D:1:2