anchor.diff:  
   %% define validity period of a product
   -type valid_period() :: daily | weekly | monthly | yealy.
  +
  +
  +%% define client table entries record
  +-record(client,
  +		{address :: inet:ip_address(),
  +		identifier = <<>> :: binary(),
  +		port :: inet:port_number(),
  +		protocol :: radius | diameter,
  +		secret :: binary(),
  +		last_modified  = {erlang:system_time(milli_seconds),
  +				erlang:unique_integer([positive])} :: tuple()}).
   
   -record(alteration,
   		{name :: string(),
  
positive.code: 		start_date :: pos_integer(), % ISO8601
  		termination_date :: pos_integer(), % ISO8601
  		price :: [#price{}]}).
  
negative.code: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  %%% 
  
  -type product_status() :: created | aborted | cancelled
  								| active | pending_active | suspended
  								| terminate | pending_terminate.
  