=cut
-__PACKAGE__->mk_classdata( 'position_column' => 'position' );
+__PACKAGE__->mk_classaccessor( 'position_column' => 'position' );
=head2 grouping_column
=cut
-__PACKAGE__->mk_classdata( 'grouping_column' );
+__PACKAGE__->mk_group_accessors( inherited => 'grouping_column' );
=head2 null_position_value
=cut
-__PACKAGE__->mk_classdata( 'null_position_value' => 0 );
+__PACKAGE__->mk_classaccessor( 'null_position_value' => 0 );
=head2 siblings
=cut
-__PACKAGE__->mk_classdata( '_initial_position_value' => 1 );
+__PACKAGE__->mk_classaccessor( '_initial_position_value' => 1 );
=head2 _next_position_value