$box{$X}{$Y}{$z} =  1;             # DOES work 
#      $box{$X}{$Y}{$z}{'rect'} = 1 ;     # 'works' because it's commented out
#      $box{$X}{$Y}{$z}{'rect'} = undef ; # see above
       $box{$X}{$Y}{$z}{'text'} = 2;      # refs error 

##</code><code>##

my $z = 1;
$z->{'text'} = 2;

##</code><code>##

$box{$X}->{$Y}->{$z} = 1;
$box{$X}->{$Y}->{$z}->{'text'} = 2; 

##</code><code>##

$box{$X}{$Y}{$z} =  undef;

##</code><code>##

       $box{$X}{$Y}{$z}{'text'} = 2;