Base Offering Circular – Multifamily 64 Class ..........................................  As to any Trust REMIC, all of the Securities that together represent one of the Regular Interests in the Trust REMIC or all of the Securities that together represent the Residual Interest in such Trust REMIC.  As to any MX Trust, all MX Securities or Modifiable Securities sharing the same designation.  As to any Callable Series, all of the securities sharing the same designation.  The Trust Agreement or MX Trust Agreement, as applicable, shall specify the designations, Original Class Principal Balances (if any), original Class Notional Balances (if any), Interest Rates (if any) and other specific characteristics of each Class of Securities. Class Factor...............................  With respect to each Class, a number truncated to eight decimal places calculated by the Trustee and published or otherwise made available to investors on or about one Business Day preceding each Distribution Date that, when multiplied by the Original Class Principal Balance (or original Class Notional Balance) of that Class, determines the Class Principal Balance (or Class Notional Balance), after giving effect to any distribution of principal to be made on the Securities (and any addition to the Class Principal Balance of any Accrual Class or Partial Accrual Class) on that Distribution Date. Class Notional Balance .............  The balance used as a reference to calculate the amount of interest due on a Notional Class. Class Principal Balance.............  As to any Class other than a Notional Class as of any Distribution Date, the Original Class Principal Balance of that Class less all payments of principal previously allocated to that Class (plus amounts, if any, added to the Class Principal Balance) on previous Distribution Dates, except as otherwise provided in the related Offering Circular and Trust Agreement or MX Trust Agreement, as applicable. Class R Security........................  A Security that represents a Residual Interest in a Trust REMIC. Class RI Security.......................  A Security that represents a Residual Interest in an Issuing REMIC. Class RP Security......................  A Security that represents a Residual Interest in a Pooling REMIC. Class RR Security .....................  A Security that represents a Residual Interest in two or more Trust REMICs. Class Type.................................  An Interest Type, Principal Type or Other Type.