* group children. default_groups may coexist alongsize make_group() or
* make_item(), but if the group wishes to have only default_groups
* children (disallowing mkdir(2)), it need not provide either function.
* group children. default_groups may coexist alongsize make_group() or
* make_item(), but if the group wishes to have only default_groups
* children (disallowing mkdir(2)), it need not provide either function.