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                                                                    EXHIBIT 4.23

                            SENIOR EXCHANGEABLE NOTE
                             DUE NOVEMBER 15, 2008

                                 [FACE OF NOTE]

                       EOP OPERATING LIMITED PARTNERSHIP

                 SENIOR EXCHANGEABLE NOTE DUE NOVEMBER 15, 2008

NO. 001                                                         PRINCIPAL AMOUNT
                                                                    $300,000,000

CUSIP No. 268766BP6

         UNLESS THIS NOTE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO EOP OPERATING
LIMITED PARTNERSHIP (THE "ISSUER") OR ITS AGENT FOR REGISTRATION OF TRANSFER,
EXCHANGE OR PAYMENT AND ANY NOTE ISSUED IS REGISTERED IN THE NAME OF CEDE CO. OR
IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC AND
ANY PAYMENT IS MADE TO CEDE CO., OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC, ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE CO., HAS AN INTEREST HEREIN.

         UNLESS AND UNTIL THIS NOTE IS EXCHANGED IN WHOLE OR IN PART FOR NOTES
IN CERTIFICATED FORM, THIS NOTE MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY DTC
TO A NOMINEE THEREOF OR BY A NOMINEE THEREOF OR BY A NOMINEE THEREOF TO DTC OR
ANOTHER NOMINEE OF DTC OR BY DTC OR ANY SUCH NOMINEE TO A SUCCESSOR OF DTC OR A
NOMINEE OF SUCH SUCCESSOR.

         THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS NOTE,
AGREES FOR THE BENEFIT OF THE ISSUER AND EQUITY OFFICE PROPERTIES TRUST ("EQUITY
OFFICE") THAT THIS NOTE MAY NOT BE RESOLD, PLEDGED OR OTHERWISE TRANSFERRED
PRIOR TO THE LATER OF (X) THE EXPIRATION OF THE HOLDING PERIOD UNDER RULE 144(k)
(OR ANY SUCCESSOR THERETO) UNDER THE SECURITIES ACT, OR (Y) THREE MONTHS AFTER
SUCH HOLDER CEASES TO BE AN "AFFILIATE" (WITHIN THE MEANING OF RULE 144 UNDER
THE SECURITIES ACT) OF THE ISSUER OR EQUITY OFFICE, IN EITHER CASE OTHER THAN
(1) TO THE ISSUER OR EQUITY OFFICE, (2) SO LONG AS THIS NOTE IS ELIGIBLE FOR
RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE 144A"), TO A PERSON
WHOM THE SELLER REASONABLY BELIEVES IS A "QUALIFIED INSTITUTIONAL BUYER" WITHIN
THE MEANING OF RULE 144A, PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A
QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR
OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (3) IN AN OFFSHORE
TRANSACTION IN ACCORDANCE WITH REGULATION S UNDER THE SECURITIES ACT, (4) TO AN
INSTITUTION THAT IS AN "ACCREDITED INVESTOR", AS DEFINED IN RULE 501(a)(1), (2),
(3) OR (7) UNDER THE SECURITIES ACT (AN "INSTITUTIONAL ACCREDITED INVESTOR"),
THAT IS ACQUIRING THIS NOTE FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION AND
THAT, PRIOR TO SUCH TRANSFER, DELIVERS TO THE ISSUER, EQUITY OFFICE AND THE
TRUSTEE A SIGNED LETTER CONTAINING CERTAIN REPRESENTATIONS AND AGREEMENTS
RELATING TO THE RESTRICTIONS ON TRANSFER OF THIS NOTE (THE FORM OF WHICH LETTER
MAY BE OBTAINED FROM THE TRUSTEE), (5) PURSUANT TO AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 (IF APPLICABLE) UNDER
THE SECURITIES ACT OR (6) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT

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UNDER THE SECURITIES ACT, IN EACH CASE IN ACCORDANCE WITH ANY APPLICABLE
SECURITIES LAWS OF ANY STATE OF THE UNITED STATES OR ANY OTHER JURISDICTION. THE
HOLDER HEREOF, BY PURCHASING THIS NOTE, REPRESENTS AND AGREES FOR THE BENEFIT OF
THE ISSUER AND EQUITY OFFICE THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER, (2)
AN INSTITUTIONAL ACCREDITED INVESTOR AND THAT IT IS HOLDING THIS NOTE FOR
INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION OR (3) NOT A U.S. PERSON AND IS
OUTSIDE THE UNITED STATES WITHIN THE MEANING OF (OR AN ACCOUNT SATISFYING THE
REQUIREMENTS OF RULE (k)(2) UNDER) REGULATION S UNDER THE SECURITIES ACT. IN ANY
CASE, THE HOLDER HEREOF WILL NOT, DIRECTLY OR INDIRECTLY, ENGAGE IN ANY HEDGING
TRANSACTION WITH REGARD TO THIS NOTE OR ANY COMMON SHARES ISSUABLE UPON EXCHANGE
OF THIS NOTE EXCEPT AS PERMITTED BY THE SECURITIES ACT.

         EOP Operating Limited Partnership, a Delaware limited partnership (the
"Issuer," which term includes any successor under the Indenture hereinafter
referred to), for value received, hereby promises to pay to Cede Co. or
registered assigns, the principal sum of Three Hundred Million Dollars, unless
previously exchanged into common shares of beneficial interest, par value $.01
per share ("Common Shares"), of Equity Office Properties Trust, a Maryland real
estate investment trust ("Equity Office"), in accordance with the terms
specified on the reverse hereof and in the Indenture, on November 15, 2008 (the
"Stated Maturity Date"), or any Redemption Date (as defined on the reverse
hereof), or any earlier date of acceleration of maturity (each such date being
referred to as the "Maturity Date" with respect to the principal repayable on
such date), and to pay interest thereon from August 23, 2000 (or from the most
recent Interest Payment Date (as defined below) to which interest has been paid
or duly provided for), semiannually in arrears on May 15 and November 15 of each
year, commencing on November 15, 2000 (each, an "Interest Payment Date"), and on
the Maturity Date, in an amount equal to the greater of (i) 7.25% per annum (or
$36.25 per $1,000 outstanding principal amount semiannually) and (ii) the
product of (A) two times the regular cash distribution most recently paid by
Equity Office on a Common Share for a fiscal quarter and (B) the number of
Common Shares into which each $1,000 outstanding principal amount is
exchangeable, until payment of said principal sum has been made or duly provided
for. Any cash distribution (or portion thereof) that is properly designated by
Equity Office as extraordinary and not expected to be recurring shall not be
taken into account for purposes of clause (A) of the preceding sentence.
Interest on this Note will be computed on the basis of a 360-day year of twelve
30-day months.

         The interest so payable and punctually paid or duly provided for on an
Interest Payment Date will, subject to certain exceptions described below, be
paid to the Holder in whose name this Note (or one or more predecessor Notes) is
registered at the close of business on the "Regular Record Date" for such
payment, which will be the May 1 or November 1 (regardless of whether such day
is a Business Day (as defined below)) next preceding such Interest Payment Date.
Any interest not so punctually paid or duly provided for on an Interest Payment
Date ("Defaulted Interest") shall forthwith cease to be payable to the Holder on
such Regular Record Date, and shall be paid to the Holder in whose name this
Note (or one or more predecessor Notes) is registered at the close of business
on a special record date (the "Special Record Date") for the payment of such
Defaulted Interest to be fixed by the Trustee hereinafter referred to, notice
whereof shall be given to the Holder of this Note by the Trustee not less than
10 calendar days prior to such Special Record Date or may be paid at any time in
any other lawful manner, all as more fully provided for in the Indenture.

         The principal of this Note payable on the Maturity Date will be paid
against presentation and surrender of this Note at the office or agency of the
Issuer maintained for that purpose in Boston, Massachusetts with a drop facility
maintained in New York, New York. The Issuer hereby initially designates the
Corporate Trust Office of the Trustee in Boston, Massachusetts as the office to
be maintained by it where Notes may be presented for payment, exchange or
registration of transfer or exchange and where notices or demands to or upon the
Issuer or Equity Office in respect of the Notes or the Indenture may be served.

         Interest payable on this Note on any Interest Payment Date and on the
Maturity Date, as the case may be, will be the amount of interest accrued during
the applicable Interest Period (as defined below). An "Interest Period" is each
period from and including the immediately preceding Interest Payment Date (or
from and including August 23, 2000 in the case of the initial Interest Period)
to but excluding the applicable

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Interest Payment Date or the Maturity Date, as the case may be. If any Interest
Payment Date or the Maturity Date falls on a day that is not a Business Day,
principal and interest payable on such date will be paid on the succeeding
Business Day with the same force and effect as if it were paid on the date such
payment was due, and no interest will accrue on the amount so payable for the
period from and after such date to such succeeding Business Day. "Business Day"
means any day, other than a Saturday or a Sunday, on which banking institutions
in New York, New York and Boston, Massachusetts are not required or authorized
by law or executive order to close.

         Payments of principal and interest in respect of this Note will be made
in immediately available funds in such coin or currency of the United States of
America as at the time of payment is legal tender for the payment of public and
private debts.

         Reference is made to the further provisions of this Note set forth on
the reverse hereof. Such further provisions shall for all purposes have the same
effect as though fully set forth at this place. Capitalized terms used herein,
including on the reverse hereof, and not defined herein or on the reverse hereof
shall have the respective meanings given to such terms in the Indenture.

         This Note shall not be entitled to the benefits of the Indenture or the
Guarantee of Equity Office or be valid or become obligatory for any purpose
until the certificate of authentication hereon shall have been signed by the
Trustee.

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         IN WITNESS WHEREOF, each of the Issuer and Equity Office has caused
this Note to be signed manually or by facsimile by an authorized signatory.

Dated: August 23, 2000                  EOP OPERATING LIMITED PARTNERSHIP,
                                        as Issuer

Attest:                                 By:  EQUITY OFFICE PROPERTY TRUST, not
                                             individually but as General Partner

By: /s/ ROBIN MARIELLA                  By: /s/ STANLEY M. STEVENS
   ----------------------------------      -------------------------------------
Name: Robin Mariella                    Name: Stanley M. Stevens
Title: Assistant Secretary              Title: Executive Vice President

                                        EQUITY OFFICE PROPERTIES TRUST

                                        By: /s/ STANLEY M. STEVENS
                                           -------------------------------------
                                        Name:  Stanley M. Stevens
                                        Title: Executive Vice President

                    TRUSTEE'S CERTIFICATE OF AUTHENTICATION

         This is one of the Notes of the series designated herein referred to in
the within-mentioned Indenture.

Dated: August 23, 2000                  STATE STREET BANK AND TRUST COMPANY,
                                        as Trustee

                                        By: /s/
                                            ------------------------------------
                                            Authorized Officer

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                               [REVERSE OF NOTE]

                       EOP OPERATING LIMITED PARTNERSHIP

                 Senior Exchangeable Note due November 15, 2008

         This Note is one of a duly authorized issue of senior debt securities
of the Issuer of the series hereinafter specified, all issued or to be issued
under and pursuant to an Indenture, dated as of August 23, 2000 (as amended, the
"Indenture"), duly executed and delivered by the Issuer and Equity Office to
State Street Bank and Trust Company, as Trustee (herein called the "Trustee,"
which term includes any successor trustee under the Indenture with respect to
the series of Notes of which this Note is a part), to which Indenture and all
indentures supplemental thereto reference is hereby made for a description of
the rights, limitations of rights, obligations, duties, and immunities
thereunder of the Trustee, the Issuer, Equity Office and the Holders of the
Notes, and of the terms upon which the Notes are, and are to be, authenticated
and delivered. The debt securities issuable under the Indenture may be issued in
one or more series, which different series may be issued in various aggregate
principal amounts, may mature at different times, may bear interest (if any) at
different rates or formulas, may be subject to different redemption or exchange
provisions (if any), and may otherwise vary as provided in the Indenture. This
Note is one of a series designated as "Senior Exchangeable Notes due November
15, 2008" of the Issuer (the "Notes"), limited in aggregate principal amount to
$375,000,000, subject to the provisions in the Indenture, and is a Guaranteed
Security within the meaning of, and subject to the provisions applicable to
Equity Office as Guarantor thereof contained in, the Indenture.

         In case an Event of Default with respect to the Notes shall have
occurred and be continuing, the principal hereof may be declared, and upon such
declaration shall become, due and payable, in the manner, with the effect, and
subject to the conditions provided in the Indenture.

         The Issuer may redeem this Note, at any time after November 15, 2004 in
whole or from time to time in part in integral multiples of $1,000 (provided
that any remaining principal amount is at least $100,000), at the option of the
Issuer, at a redemption price (the "Redemption Price") equal to 100% of the
principal amount being redeemed plus unpaid interest accrued thereon to the date
fixed for redemption (the "Redemption Date"); provided, however, that interest
installments due on an Interest Payment Date which is on or prior to the
Redemption Date will be payable to the Holder hereof (or one or more predecessor
Notes) as of the close of business on the Regular Record Date preceding such
Interest Payment Date. If notice has been given as provided in the Indenture and
funds for the redemption of this Note or any part hereof called for redemption
shall have been made available on the Redemption Date, this Note or such part
will cease to bear interest on the Redemption Date referred to in such notice
and the only right of the Holder will be to receive payment of the Redemption
Price. Notice of any optional redemption of any Notes will be given to the
Holder hereof (in accordance with the provisions of the Indenture) not more than
60 nor less than 30 days prior to the Redemption Date. In the event of
redemption of this Note in part only, a new Note of like tenor for the
unredeemed portion hereof and otherwise having the same terms and provisions as
this Note shall be issued by the Issuer in the name of the Holder hereof upon
the presentation and surrender hereof.

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         The Indenture contains provisions permitting the Issuer, Equity Office
and the Trustee, with the consent of the Holders of not less than a majority of
the aggregate principal amount of debt securities issued under the Indenture at
the time Outstanding of all series to be affected (voting as one class),
evidenced as provided in the Indenture, to execute supplemental indentures
adding any provisions to or changing in any manner or eliminating any of the
provisions of the Indenture or of any supplemental indenture or modifying in any
manner the rights of the Holders of the Notes of each series; provided, however,
that no such supplemental indenture shall, without the consent of the Holder of
each Note at the time Outstanding if so affected, (i) change the Stated Maturity
of any principal or interest payment on any Note, or reduce the principal amount
thereof or the rate or amount (or manner of calculation of the amount) of any
interest thereon, or change the timing or reduce the amount payable upon the
redemption thereof, or change the Place of Payment or currency for payments
thereon, or impair or affect the rights of any Holder to institute suit for the
payment on or exchange of any Note, or (ii) reduce the percentage in principal
amount of Outstanding Notes the Holders of which are required to consent to any
such supplemental indenture or any waiver of compliance with certain provisions
of the Indenture or any waiver of certain defaults thereunder, or (iii) modify
this provision or the provisions applicable to waivers except to increase the
required percentages, or (iv) modify Equity Office's Guarantee of the Notes, or
(v) change the exchange provisions applicable to the Notes in a manner adverse
to the Holders thereof. It is also provided in the Indenture that, with respect
to certain defaults or Events of Default regarding the debt securities of any
series, the Holders of a majority in aggregate principal amount Outstanding of
the debt securities of such series (or, in the case of certain defaults or
Events of Default, all series of debt securities) may on behalf of the Holders
of all the debt securities of such series (or all of the debt securities, as the
case may be) waive any such past default or Event of Default and its
consequences, prior to any declaration accelerating the maturity of such debt
securities, or, subject to certain conditions, may rescind a declaration of
acceleration and its consequences with respect to such debt securities. The
preceding sentence shall not, however, apply to a default in or Event of Default
relating to the payment of the principal of or interest on any of the debt
securities or in delivery by Equity Office of Common Stock and cash, if
applicable, upon an exchange of debt securities or in respect of a covenant or
provision contained in the Indenture that cannot be modified or amended without
the consent of the Holders of each debt security at the time Outstanding
affected thereby. Any such consent or waiver by the Holder of this Note (unless
revoked as provided in the Indenture) shall be conclusive and binding upon such
Holder and upon all future Holders and owners of this Note and any Note that may
be issued in exchange or substitution herefor, irrespective of whether or not
any notation thereof is made upon this Note or such other Notes.

         The principal amount (or portion of the principal amount that is an
integral multiple of $1,000, provided any remaining principal amount is at least
$100,000) of this Note will be exchangeable (unless it has matured or has been
previously redeemed by the Issuer), in whole or in part at any time on or after
the 90th day following the initial issuance of the Notes on August 23, 2000, at
the option of the Holder hereof, into Common Shares of Equity Office at an
initial exchange price of $34.00 per share, subject to adjustment under certain
conditions specified in the Indenture (the "Exchange Price"). The right to
exchange any or all of this Note if called for redemption will terminate at the
close of business on the Business Day preceding the applicable Redemption Date,
unless the Issuer defaults in the payment of the requisite Redemption Price

                                       6

<PAGE>

when due, in which case the Holder's exchange rights will terminate at the close
of business on the date such payment is made.

         Notwithstanding the preceding paragraph, if the Current Market Price
per Common Share on the New York Stock Exchange on the date, if any, that the
Holder elects to exercise its exchange rights is less than the Exchange Price,
then the exchanging Holder will receive, in lieu of Common Shares, cash in an
amount equal to 97% of the product of (i) the number of Common Shares into which
the principal amount of this Note subject to the election would otherwise be
exchangeable and (ii) such Current Market Price per Common Share.

         Owners of beneficial interests herein may exercise their exchange
rights by delivery to DTC of the appropriate instructions for exchange pursuant
to the procedures of DTC and its direct and indirect participants.

         The Holder of this Note at the close of business on a Regular Record
Date will be entitled to receive the interest payable on the related Interest
Payment Date notwithstanding the exchange of all or any portion of this Note
following such Regular Record Date and prior to such Interest Payment Date.
However, if this Note is surrendered for exchange during the period between the
close of business on any Regular Record Date and ending with the opening of
business on the related Interest Payment Date (unless this Note is exchanged
after the issuance of a notice of redemption with respect to a Redemption Date
during such period or coinciding with such Interest Payment Date) must be
accompanied by payment of an amount equal to the interest payable thereon on
such Interest Payment Date. The Holder of this Note on a Regular Record Date who
(or whose transferee) presents and surrenders all or any portion of this Note
for exchange on such Interest Payment Date will receive the interest payable on
such date, and the exchanging Holder need not include payment of the amount of
such interest upon presenting and surrendering all or any portion of this Note
for exchange. Except as provided above, neither the Issuer nor Equity Office
will make any payment or allowance for unpaid interest, whether or not in
arrears, on the principal amount of this Note presented and surrendered for
exchange or for any distribution on the Common Shares that are issued upon such
exchange if the record date for such distribution was prior to the effective
time of such exchange, as determined pursuant to the Indenture.

         Fractional Common Shares will not be issued upon exchange but, in lieu
thereof, Equity Office will pay a cash adjustment based on the Current Market
Price of the Common Share at the close of business on the Trading Day prior to
such exchange.

         The Holder hereof agrees to be bound by the provisions of the
Registration Rights Agreement relating to the Notes. The Issuer and Equity
Office agree that the Holder hereof will be entitled to Liquidated Damages under
certain conditions specified in the Registration Rights Agreement. All
references herein to interest shall include such Liquidated Damages.

         No reference herein to the Indenture and no provision of this Note or
the Indenture shall alter or impair the obligation of the Issuer, which is
absolute and unconditional, to pay the principal of, and interest on, this Note
in the manner, at the respective times, at the rate and in the coin or currency
herein prescribed or alter or impair the obligations of Equity Office in respect
of

                                       7


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its unconditional guarantee of the aforementioned payments or its delivery of
Common Shares and cash, if applicable, upon an exchange of this Note.

         This Note is issuable only in fully registered form, without coupons,
in denominations of $100,000 and integral multiples of $1,000 thereof. This Note
may be exchanged for a like aggregate principal amount of Notes of other
authorized denominations at the office or agency of the Issuer in Boston,
Massachusetts, in the manner and subject to limitations provided herein and in
the Indenture, but without the payment of any change except for any tax or other
governmental charge imposed in connection therewith.

         Upon due presentment for registration of transfer of this Note at the
office or agency of the Issuer in Boston, Massachusetts, one or more new Notes
of authorized denominations in an equal aggregate principal amount will be
issued to the transferee in exchange therefor, subject to the limitations
provided herein and in the Indenture, but without the payment of any service
charge except for any tax or other governmental charge imposed in connection
therewith.

         This Note is not subject to a sinking fund requirement.

         No recourse under or upon any obligation, covenant or agreement
contained in the Indenture or any Note, or because of any indebtedness evidenced
hereby or thereby (including, without limitation, any obligation or indebtedness
relating to the principal of, or interest or any other amounts due, or claimed
to be due, on this Note), or for any claim based thereon or otherwise in respect
thereof, shall be had (i) against the any partner other than Equity Office, as
Guarantor, or any Person which owns an interest, directly or indirectly, in any
partner, in the Issuer, or (ii) against any promoter, as such, or against any
past, present or future shareholder, officer, trustee or partner, as such, of
the Issuer or Equity Office or any successor, either directly or through the
Issuer or Equity Office or any successor, under any rule of law, statute or
constitutional provision or by the enforcement of any assessment or by any legal
or equitable proceeding or otherwise, all such liability being expressly waived
and released by the acceptance hereof and as part of the consideration for the
issue hereof.

         The Issuer, Equity Office, the Trustee and any authorized agent of the
Issuer, Equity Office or the Trustee may deem and treat the Person in whose name
this Note is registered as the Holder and absolute owner of this Note (whether
or not this Note shall be overdue and notwithstanding any notation of ownership
or other writing hereon), for the purpose of receiving payment of, or on account
of, the principal hereof and, subject to the provisions herein and on the face
hereof, interest hereon, and for all other purposes, and none of the Issuer,
Equity Office or the Trustee nor any authorized agent of the Issuer, Equity
Office or the Trustee shall be affected by any notice to the contrary, except as
required by law.

         THE INDENTURE AND THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAW OF THE STATE OF NEW YORK, UNITED STATES OF AMERICA
WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAWS.

                                       8

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                  ASSIGNMENT FORM AND CERTIFICATE OF TRANSFER

        To assign this Note fill in the form below:

        (I)  or (we) assign and transfer this Note to

        ------------------------------------------------------------------------
        (Insert assignee's social security or tax identification number, if any)

        ------------------------------------------------------------------------
        ------------------------------------------------------------------------
        ------------------------------------------------------------------------
        (Print or type assignee's name, address and zip code)

Your signature:
              ------------------------------------------------------------------
              (Sign exactly as your name appears on the other side of this Note)

Date:
     ----------------------------------------
Signature Guarantee:*
                     ------------------------
       [For inclusion only if this Note bears a Restricted Securities Legend] In
        connection with any transfer of any of the Notes evidenced by this
        certificate which are "restricted securities" (as defined in Rule 144
        (or any successor thereto) under the Securities Act), the undersigned
        confirms that such Notes are being transferred:

CHECK ONE BOX BELOW

        (1)    [  ]  To the Issuer or Equity Office; or

        (2)    [  ]  pursuant to and in compliance with Rule 144A under the
                     Securities Act; or

        (3)    [  ]  pursuant to and in compliance with Regulation S under
                     the Securities Act; or

        (4)    [  ]  to an institutional "accredited investor" (as defined in
                     Rule 501(a)(1), (2), (3) or (7) under the Securities Act)
                     that has furnished to the Trustee a signed letter
                     containing certain representations and agreements (the
                     form of which  letter can be obtained from the Trustee); or

---------------------

*           Signature must be guaranteed by a commercial bank, trust company or
            member firm or a major stock exchange.

                                       9



<PAGE>

        (5)    [  ]  Pursuant to an effective registration statement under the
                     Securities Act provided by Rule 144 thereunder; or

        (6)    [  ]  Pursuant to an effective registration statement under the
                     Securities Act.

Unless one of the boxes is checked, the Registrar will refuse to register any of
the Notes evidenced by this certificate in the name of any person other than the
Holder thereof; provided, however, that if box (3), (4) or (5) is checked, the
Trustee may require, prior to registering any such transfer of such Notes, such
certifications and other information and, if box (5) is checked, a legal
opinion, as the Issuer has reasonably requested in writing, by delivery to the
Trustee of a standing letter of instruction, to confirm that such transfer is
being made pursuant to an exemption from or in a transaction not subject to the
registration requirements of the Securities Act; provided that this paragraph
shall not be applicable to any Notes which are not "restricted securities" (as
defined in Rule 144 (or any successor thereto) under the Securities Act.

                Your Signature:
                                        ----------------------------------------
                                        (Sign exactly as your name appears
                                        on the other side of this Note)

                Date:
                     --------------------------------


Medallion Signature Guarantee:

-----------------------------------------

                                       10