declare
        v_parent_sk     varbit default null;
        v_max_value     integer;
begin
        select max(tree_leaf_key_to_int(tree_sortkey)) into v_max_value 
          from acs_object_types 
         where supertype = new.supertype;

        select tree_sortkey into v_parent_sk 
          from acs_object_types 
         where object_type = new.supertype;

        new.tree_sortkey := tree_next_key(v_parent_sk ,v_max_value);

        return new;

end;