<PAGE>

                                                 Executed in 6 Parts
                                               Counterpart No. (   )


                     NATIONAL EQUITY TRUST

                LOW FIVE PORTFOLIO SERIES 215

                   REFERENCE TRUST AGREEMENT

       This Reference Trust Agreement dated February 23, 2000 among
Prudential Securities Incorporated, as Depositor and The Chase Manhat-
tan Bank, as Trustee, sets forth certain provisions in full and incor-
porates other provisions by reference to the document entitled
"National Equity Trust Low Five Portfolio Series, Trust Indenture and
Agreement" (the "Basic Agreement") dated April 25, 1995.  Such provi-
sions as are set forth in full herein and such provisions as are in-
corporated by reference constitute a single instrument (the
"Indenture").

                        WITNESSETH THAT:


       In consideration of the premises and of the mutual agree-
ments herein contained, the Depositor and the Trustee agree as fol-
lows:

                            Part I.


             STANDARD TERMS AND CONDITIONS OF TRUST


       Subject to the provisions of Part II hereof, all the provi-
sions contained in the Basic Agreement are herein incorporated by ref-
erence in their entirety and shall be deemed to be a part of this in-
strument as fully and to the same extent as though said provisions had
been set forth in full in this instrument except that the Basic Agree-
ment is hereby amended in the following manner:


<PAGE>

                              -2-

  A.   Article I, entitled "Definitions", paragraph 22, shall be
       amended as follows:


       "Trustee shall mean The Chase Manhattan Bank
       or any successor trustee appointed as
       hereinafter provided."



  B.   Article II, entitled "Deposit of Securities; Acceptance of
       Trust", shall be amended as follows:


       The second sentence of Section 2.03 Issue of Units
       shall be amended by deleting the words "on any day on
       which the Depositor is the only Unit Holder."


  C.   Article III, entitled "Administration of Trust", shall be
       amended as follows:


       (i)  Section 3.01 Initial Costs shall be amended to
            substitute the following language:

            Section 3.01.  Initial Cost  The costs of organizing
            the Trust and sale of the Trust Units shall, to the
            extent of the expenses reimbursable to the Depositor as
            provided below, be borne by the Unit Holders, provided,
            however, that, to the extent all of such costs are not
            borne by Unit Holders, the amount of such costs not
            borne by Unit Holders shall be borne by the Depositor
            and, provided further, however, that the liability on
            the part of the Depositor under this section shall not
            include any fees or other expenses incurred in
            connection with the administration of the Trust
            subsequent to the deposit referred to in Section 2.01.
            Upon notification from the Depositor that the primary
            offering period is concluded, the Trustee shall
            withdraw from the Account or Accounts specified in the
            Prospectus or, if no Account is therein specified, from
            the Principal Account, and pay to the Depositor the
            Depositor's reimbursable expenses of organizing the
            Trust and sale of the Trust Units in an amount
            certified to the Trustee by the Depositor.  If the
            balance of the Principal Account is insufficient to
            make such withdrawal, the Trustee shall, as directed by
            the Depositor, sell Securities identified by the
            Depositor, or distribute to the Depositor Securities

<PAGE>

                              -3-

            having a value, as determined under Section 4.01 as of
            the date of distribution, sufficient for such
            reimbursement.  The reimbursement provided for in this
            section shall be for the account of the Unitholders of
            record at the conclusion of the primary offering period
            and shall not be reflected in the computation of the
            Unit Value prior thereto.  As used herein, the
            Depositor's reimbursable expenses of organizing the
            Trust and sale of the Trust Units shall include the
            cost of the initial preparation and typesetting of the
            registration statement, prospectuses (including
            preliminary prospectuses), the indenture, and other
            documents relating to the Trust, SEC and state blue sky
            registration fees, the cost of the initial valuation of
            the portfolio and audit of the Trust, the initial fees
            and expenses of the Trustee, and legal and other out-
            of-pocket expenses related thereto, but not including
            the expenses incurred in the printing of preliminary
            prospectuses and prospectuses, expenses incurred in the
            preparation and printing of brochures and other
            advertising materials and any other selling expenses.
            Any cash which the Depositor has identified as to be
            used for reimbursement of expenses pursuant to this
            Section shall be reserved by the Trustee for such
            purpose and shall not be subject to distribution or,
            unless the Depositor otherwise directs, used for
            payment of redemptions in excess of the per-Unit amount
            allocable to Units tendered for redemption.  As
            directed by the Depositor, the Trustee will advance
            funds to the Trust in an amount necessary to reimburse
            the Depositor pursuant to this Section and shall
            recover such advance from the sale or sales of
            Securities at such time as the Depositor shall direct,
            but in no event later than the termination of the
            Trust.  Repayment of any such advance shall be secured
            by a lien on the assets of the Trust prior to the
            interest of the Unit Holders as provided in Section
            6.04.


      (ii)  The third paragraph of Section 3.05 Distribution
            shall be amended to add the following sentence at
            the end thereof:

            "The Trustee shall make a special distribution of
            the cash balance in the Income and Principal ac-
            counts available for such distribution to Unit
            Holders of record on such dates as the Depositor
            shall direct."


<PAGE>

                              -4-

     (iii)  The second to the last paragraph of Section 3.08
            Sale of Securities shall be  amended to replace
            the word "equal" with the following phrase: "be
            sufficient to pay."



  D.   Reference to United States Trust Company of New York in its
       capacity as Trustee is replaced by the Chase Manhattan Bank
       throughout the Basic Agreement.


                            Part II.

             SPECIAL TERMS AND CONDITIONS OF TRUST


       The following special terms and conditions are hereby agreed
to:

       A.   The Trust is denominated National Equity Trust, Low
  Five Portfolio Series 215.

       B.   The Units of the Trust shall be subject to a deferred
  sales charge.

       C.   The contracts for the purchase of common stock listed
  in Schedule A hereto are those which, subject to the terms of
  this Indenture, have been or are to be deposited in Trust under
  this Indenture as of the date hereof.

       D.   The term "Depositor" shall mean Prudential Securities
  Incorporated.

       E.   The aggregate number of Units referred to in Sec-
  tions 2.03 and 9.01 of the Basic Agreement is 250,000 as of the
  date hereof.

       F.   A Unit of the Trust is hereby declared initially equal
  to 1/250,000th of the Trust.

       G.   The term "First Settlement Date" shall mean
  February 29, 2000.

       H.   The terms "Computation Day" and "Record Date" shall
  mean quarterly on the tenth day of April, July, October,
  and January commencing April 10, 2000.

<PAGE>

                              -5-

       I.   The term "Distribution Date" shall mean quarterly on
  the twenty-fifth day of April, July, October, and January
  commencing April 25, 2000 or as soon thereafter as possible.

       J.   The term "Termination Date" shall mean February 20, 2002.

       K.   The Trustee's Annual Fee shall be $.95 (per 1,000
  Units) for 100,000,000 and above units outstanding; $1.01 (per
  1,000 Units) for 50,000,000 - 99,999,999 units outstanding; $1.05
  (per 1,000 Units) for 49,999,999 and below units outstanding.  In
  calculating the Trustee's annual fee, the fee applicable to the
  number of units outstanding shall apply to all units outstanding.

       L.   The Depositor's Portfolio supervisory service fee shall
  be $0.25 per 1,000 Units.

       [Signatures and acknowledgments on separate pages]


<PAGE>

                              -6-

       The Schedule of Portfolio Securities in Part A of the pro-
       spectus included in this Registration Statement for National
       Equity Trust, Low Five Portfolio Series 215 is hereby incor-
       porated by reference herein as Schedule A hereto.