anchor.diff:      transfers = [] :: [transfer:id()]
   }).
   
  -
   %% File handle used by the module
   -record(sfm_handle, {
       helper_handle :: undefined | helpers:handle(),
  
positive.code:     revision_history = [] :: [subscriptions:rev()]
  }).
  
  
  %% Message ID containing recipient for remote response.
  -record(message_id, {
  
negative.code:     id :: undefined | binary(),
      recipient :: pid() | undefined
  }).
  
  % State of subscription tracking.
  -record(subscriptions_state, {
  