package Node;

use constant FIRST_IDX  => 0;
use constant IDX_PARENT => FIRST_IDX + 0;
use constant NEXT_IDX   => FIRST_IDX + 1;

##</code><code>##

package ElementNode;

BEGIN { our @ISA = 'Node'; }

use constant FIRST_IDX => __PACKAGE__->SUPER::NEXT_IDX();
use constant IDX_NAME  => FIRST_IDX + 0;
use constant IDX_ATTS  => FIRST_IDX + 1;
use constant NEXT_IDX  => FIRST_IDX + 2;

##</code><code>##

use constant IDX_PARENT => __PACKAGE__->SUPER::IDX_PARENT();

##</code><code>##

package Node;

use constant FIRST_IDX  => 0;
use constant IDX_PARENT => FIRST_IDX + 0;
use constant IDX_ISROOT => FIRST_IDX + 1;
use constant NEXT_IDX   => FIRST_IDX + 2;