anchor.diff:  				| {disabled, SessionList}
   				| {error, Reason},
   		Service :: #service{},
  -		GrantedAmount :: {Type, Amount},
  -		Type :: octets | seconds | messages,
  +		GrantedAmount :: {Units, Amount},
   		Amount :: integer(),
   		Rated :: [#rated{}],
   		SessionList :: [{pos_integer(), [tuple()]}],
  
positive.code: 		ServiceId :: integer() | undefined,
  		ChargingKey :: integer() | undefined,
  		UnitSize :: integer() | undefined,
  		Currency :: string(),
  		UnitPrice :: integer() | undefined,
  		PriceChars :: #char_value_use{} | undefined,
  		Units :: integer() | undefined,
  		Flag :: initial | interim | final | event,
  		DebitAmounts :: list(),
  		ReserveAmounts :: list() | undefined,
  
negative.code: 		(is_integer(ServiceId) or (ServiceId== undefined)),
  		(is_integer(UnitSize) or (UnitSize == undefined)),
  		(is_integer(UnitPrice) or (UnitPrice == undefined)),
  		(is_atom(Units) or (Units == undefined)),
  		(is_list(Currency) or is_integer(Currency)),
  		((Flag == initial) or (Flag == interim) or (Flag == final) or (Flag == event)),
  		is_list(DebitAmounts),
  		(is_list(ReserveAmounts) or (ReserveAmounts == undefined)),
  