 grant delete on table sg_public.follow to sg_user, sg_admin;
 create policy delete_follow on sg_public.follow
   for select to sg_user, sg_admin
-  using (user_id = current_setting('jwt.claims.user_id')::uuid); -- TODO comment
+  using (user_id = current_setting('jwt.claims.user_id')::uuid);
+comment on policy delete_follow on sg_public.follow
+  is 'A user or admin can delete their own follows.';
 
 -- Select notice: user or admin self.
 grant select on table sg_public.notice to sg_user, sg_admin;
 create policy select_notice on sg_public.notice
   for select to sg_user, sg_admin
-  using (user_id = current_setting('jwt.claims.user_id')::uuid); -- TODO comment
+  using (user_id = current_setting('jwt.claims.user_id')::uuid);
+comment on policy select_notice on sg_public.notice
+  is 'A user or admin can select their own notices.';
 
 -- Insert notice: none.
 

grant delete on table sg_public.user_subject to sg_user, sg_admin;
create policy delete_user_subject on sg_public.user_subject
  for delete to sg_user, sg_admin
  using (id = current_setting('jwt.claims.user_id')::uuid); -- TODO comment

-- Select response: any self.
-- TODO

  entity_id uuid primary key default uuid_generate_v4(),
  entity_kind sg_public.entity_kind not null
);
comment on table sg_public.entity
  is 'A list of all entity IDs and their kinds.';
comment on column sg_public.entity.entity_id
  is 'The overall ID of the entity.';
comment on column sg_public.entity.entity_kind
  is 'The kind of entity the ID represents.';

create table sg_public.unit_version (
  -- all entity columns
  version_id uuid primary key default uuid_generate_v4(),
  created timestamp not null default current_timestamp,
  modified timestamp not null default current_timestamp,
