anchor.diff:  
   %%%%%%%%%%%%%%%%%%%%
   %% Unused chef_object behavior callbacks
  +%%
  +%% Revisions cannot be updated and have no authz_id of their own.
   %%%%%%%%%%%%%%%%%%%%
   
  -% update_from_ejson/2 (behaviour 'chef_object')
  -% update_query/0 (behaviour 'chef_object')
   
   authz_id(#oc_chef_policy_revision{}) ->
       error(not_implemented).
  
positive.code:     SerializedObject = jiffy:decode(chef_db_compression:decompress(CompressedSerializedObject)),
      Revision#oc_chef_policy_revision{serialized_object = SerializedObject}.
  
  %% TODO: this ignores revision_id and is wrong
  delete(ObjectRec = #oc_chef_policy_revision{
                        org_id = OrgId,
                        last_updated_by = _AuthzId
  
negative.code: ejson_for_indexing(#oc_chef_policy_revision{}, _EjsonTerm) ->
     {[]}.
  
  fields_for_fetch(#oc_chef_policy_revision{org_id = OrgId, name = Name, revision_id = RevisionId}) ->
      [Name, OrgId, RevisionId].
  
  