anchor.diff:  		start_date :: pos_integer() | undefined,
   		end_date :: pos_integer() | undefined,
   		type :: price_type() | undefined,
  -		period :: valid_period() | undefined,
  +		period :: recur_period() | undefined,
   		units :: unit_of_measure() | undefined,
   		size :: integer() | undefined,
   		amount :: integer() | undefined,
  
positive.code: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  %%% 
  
  -type product_offering_status() :: in_study | in_design | in_test
  		| active | rejected | launched | retired | obsolete.
  -type product_status() :: created | pending_active | aborted
  		| cancelled | active | suspended | pending_terminate | terminated.
  
negative.code: 		start_date :: pos_integer() | undefined,
  		end_date :: pos_integer() | undefined,
  		type :: price_type() | undefined,
  		period :: recur_period() | undefined,
  		units :: unit_of_measure() | undefined,
  		size :: integer() | undefined,
  		amount :: integer() | undefined,
  