<PAGE>   1
                                                                    EXHIBIT 10.4

================================================================================
                      LIBERTY PROPERTY LIMITED PARTNERSHIP
                                     ISSUER

                                       TO

                       THE FIRST NATIONAL BANK OF CHICAGO
                                     TRUSTEE

                                   -----------

                          FIRST SUPPLEMENTAL INDENTURE

                          DATED AS OF OCTOBER 24, 1997

                                   -----------


                          FIXED RATE AND FLOATING RATE
                        MEDIUM-TERM NOTES DUE NINE MONTHS
                           OR MORE FROM DATE OF ISSUE

                                   -----------


                            SUPPLEMENT TO INDENTURE,
                      DATED AS OF OCTOBER 24, 1997, BETWEEN
                    LIBERTY PROPERTY LIMITED PARTNERSHIP AND
                       THE FIRST NATIONAL BANK OF CHICAGO

================================================================================

<PAGE>   2



                  FIRST SUPPLEMENTAL INDENTURE, dated as of October 24, 1997,
between LIBERTY PROPERTY LIMITED PARTNERSHIP, a Pennsylvania limited partnership
(the "Company"), having its principal offices at 65 Valley Stream Parkway,
Malvern, Pennsylvania 19355, and THE FIRST NATIONAL BANK OF CHICAGO, a national
banking association organized under the laws of the United States of America, as
trustee (the "Trustee"), having its Corporate Trust Office at One First National
Plaza, Suite 0126, Chicago, Illinois 60670-0126.

                                    RECITALS

                  WHEREAS, the Company executed and delivered its Indenture (the
"Original Indenture"), dated as of October 24, 1997, to the Trustee to issue
from time to time for its lawful purposes debt securities evidencing its
unsecured indebtedness.

                  WHEREAS, the Original Indenture provides that by means of a
supplemental indenture, the Company may create one or more series of its debt
securities and establish the form and terms and conditions thereof.

                  WHEREAS, the Company intends by this Supplemental Indenture to
(i) create a series of debt securities, to be issued from time to time in an
aggregate principal amount not to exceed $200,000,000, entitled "Medium-Term
Notes Due Nine Months or More From Date of Issue" (the "Notes"); and (ii) (iii)
establish the forms and the terms and conditions of such Notes.

                  WHEREAS, the Board of Trustees of Liberty Property Trust (the
"Trust"), the general partner of the Company, has approved the creation of the
Notes and the form, terms and conditions thereof.

                  WHEREAS, the consent of Holders to the execution and delivery
of this Supplemental Indenture is not required, and all other actions required
to be taken under the Original Indenture with respect to this Supplemental
Indenture have been taken.

                  NOW, THEREFORE IT IS AGREED:

                                   ARTICLE ONE
         DEFINITIONS, CREATION, FORM AND TERMS AND CONDITIONS OF THE DEBT 
SECURITIES

         SECTION 1.01  DEFINITIONS. Capitalized terms used in this Supplemental
Indenture and not otherwise defined shall have the meanings ascribed to them in
the Original Indenture. In addition, the following terms shall have the
following meanings to be equally applicable to both the singular and the plural
forms of the terms defined:

                  "FIXED RATE NOTES" means the Company's Fixed Rate Notes due
nine months or more from date of issue, a form of which is attached hereto as
Exhibit A.

                  "FLOATING RATE NOTES" means the Company's Floating Rate Notes
due nine months or more from date of issue, a form of which is attached hereto
as Exhibit B.



<PAGE>   3



                  "INDENTURE" means the Original Indenture as supplemented by 
this First Supplemental Indenture.

                  "INTERCOMPANY DEBT" means Debt to which the only parties are
the Trust, any of its subsidiaries, the Company and any Subsidiary, or Debt owed
to the Trust arising from routine cash management practices, but only so long as
such Debt is held solely by any of the Trust, any of its subsidiaries, the
Company and any Subsidiary.

                  "PRICING SUPPLEMENT" means a pricing supplement to the
Prospectus, dated October 24, 1997, as supplemented by the Prospectus
Supplement, dated October 24, 1997, establishing the terms of the applicable
Notes.

         SECTION 1.02  CREATION OF THE DEBT SECURITIES. In accordance with
Section 301 of the Original Indenture, the Company hereby creates the Notes as a
separate series of its debt securities issued pursuant to the Indenture. The
Notes shall be issued from time to time in an aggregate principal amount not to
exceed $200,000,000.

         SECTION 1.03  FORM OF THE DEBT SECURITIES. Each Note will be issued in
fully registered book-entry form or in certificated form, as specified in the
applicable Pricing Supplement. The Fixed Rate Notes shall be in the form of
Exhibit A attached hereto and the Floating Rate Notes shall be in the form of
Exhibit B attached hereto.

         SECTION 1.04  TERMS AND CONDITIONS OF THE DEBT SECURITIES. The Notes
shall be governed by all the terms and conditions of the Original Indenture, as
supplemented by this First Supplemental Indenture, and in particular, the terms
of the Notes shall be as set forth from time to time in the applicable Notes and
the related Pricing Supplement. All such terms and conditions set forth in such
Notes and in such Pricing Supplement are incorporated by reference into this
Supplemental Indenture. In addition, the provisions of Article 14 of the
Original Indenture shall apply to the Notes.

                                   ARTICLE TWO
                              ADDITIONAL COVENANTS

         The Notes shall be governed by all the covenants contained in the
Original Indenture, as supplemented by this First Supplemental Indenture, and in
particular, this First Supplemental Indenture amends Section 1004 of the
Original Indenture to read as follows:

         "SECTION 1004.  Limitations on Incurrence of Debt.

         (a)      The Company will not, and will not permit any Subsidiary to, 
incur any Debt, other than Intercompany Debt, that is subordinate in right of
payment to the Notes, if, immediately after giving effect to the incurrence of
such Debt and the application of the proceeds thereof, the aggregate principal
amount of all outstanding Debt of the Company and its Subsidiaries on a
consolidated basis determined in accordance with GAAP is greater than 60% of the
sum of (i) the Company's Adjusted Total Assets as of the end of the most recent
fiscal quarter prior to the incurrence of such additional Debt and (ii) the
increase in Adjusted Total Assets since the end of such quarter (including any
increase resulting from the incurrence of additional Debt).


                                        2


<PAGE>   4



         (b)      The Company will not, and will not permit any Subsidiary to, 
incur any Debt if the ratio of Consolidated Income Available for Debt Service to
the Annual Service Charge on the date on which such additional Debt is to be
incurred would have been less than 1.5 to 1, on a pro forma basis, after giving
effect to the incurrence of such Debt and to the application of the proceeds
thereof.

         (c)      The Company will not, and will not permit any Subsidiary to, 
incur any Debt secured by any mortgage, lien, charge, pledge, encumbrance or
security interest of any kind upon any of the properties of the Company or any
Subsidiary ("Secured Debt"), whether owned at the date hereof or hereafter
acquired, if, immediately after giving effect to the incurrence of such Secured
Debt and the application of the proceeds thereof, the aggregate principal amount
of all outstanding Secured Debt of the Company and its Subsidiaries on a
consolidated basis is greater than 40% of the sum of (i) the Company's Adjusted
Total Assets as of the end of the most recent fiscal quarter prior to the
incurrence of such additional Debt and (ii) the increase in Adjusted Total
Assets since the end of such quarter (including any increase resulting from the
incurrence of additional Debt).

         (d)      The Company will at all time maintain an Unencumbered Total 
Asset Value in an amount not less than 150% of the aggregate principal amount of
all outstanding unsecured Debt of the Company and its Subsidiaries on a
consolidated basis.

                  For purposes of the foregoing provisions regarding the
limitation on the incurrence of Debt, Debt shall be deemed to be "incurred" by
the Company or a Subsidiary whenever the Company or such Subsidiary shall
create, assume, guarantee or otherwise become liable in respect thereof."

                                  ARTICLE THREE
                                     TRUSTEE

         SECTION 3.01  TRUSTEE. The Trustee shall not be responsible in any
manner whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or the due execution thereof by the Company. The recitals
of fact contained herein shall be taken as the statements solely of the Company,
and the Trustee assumes no responsibility for the correctness thereof.

                                  ARTICLE FOUR
                            MISCELLANEOUS PROVISIONS

         SECTION 4.01  RATIFICATION OF ORIGINAL INDENTURE. This Supplemental
Indenture is executed and shall be construed as an indenture supplemental to the
Original Indenture, and as supplemented and modified hereby, the Original
Indenture is in all respects ratified and confirmed, and the Original Indenture
and this Supplemental Indenture shall be read, taken and construed as one and
the same instrument.

         SECTION 4.02  EFFECT OF HEADINGS. The Article and Section headings
herein are for convenience only and shall not affect the construction hereof.


                                        3


<PAGE>   5



         SECTION 4.03  SUCCESSORS AND ASSIGNS. All covenants and agreements in
this Supplemental Indenture by the Company shall bind its successors and
assigns, whether so expressed or not.

         SECTION 4.04  SEPARABILITY CLAUSE. In case any one or more of the
provisions contained in this Supplemental Indenture shall for any reason be held
to be invalid, illegal or unenforceable in any respect, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby.

         SECTION 4.05  GOVERNING LAW. This Supplemental Indenture shall be
governed by and construed in accordance with the laws of the State of New York.
This Supplemental Indenture is subject to the provisions of the Trust Indenture
Act, that are required to be part of this Supplemental Indenture and shall, to
the extent applicable, be governed by such provisions.

         SECTION 4.06  COUNTERPARTS. This Supplemental Indenture may be executed
in any number of counterparts, and each of such counterparts shall for all
purposes be deemed to be an original, but all such counterparts shall together
constitute one and the same instrument.


                                        4


<PAGE>   6



         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed, and their respective corporate seals to be
hereunto affixed and attested, all as of the date first above written.

                                   LIBERTY PROPERTY LIMITED PARTNERSHIP

                                       By:   Liberty Property Trust,
                                                     as its sole General Partner

                                       By: /s/ Willard G. Rouse III
                                          --------------------------------------
                                          Name:   Willard G. Rouser III
                                          Title:  Chairman and Chief
                                                  Executive Officer
Attest:

/s/ James J. Bowes
--------------------------------
Name:  James J. Bowes
Title: Secretary

                                       THE FIRST NATIONAL BANK OF CHICAGO,
                                          as Trustee

                                       By: /s/ Richard D. Manella
                                          --------------------------------------
                                          Name:  Richard D. Manella
                                          Title: Vice President

Attest:
/s/ Mark J. Frye
--------------------------------
Name:   Mark J. Frye
Title:  Assistant Vice President


                                        5


<PAGE>   7



STATE OF  PA         )
                     ) ss:
COUNTY OF CHESTER    )

         On the 22nd day of October 1997, before me personally came
Willard G. Rouse III, to me known, who, being by me duly sworn, did depose and
say that he/she resides at 65 Valley Stream Parkway, that he/she is
Chairman and CEO of LIBERTY PROPERTY TRUST, the sole general partner of LIBERTY
PROPERTY LIMITED PARTNERSHIP, one of the parties described in and which executed
the foregoing instrument, and that he/she signed his/her name thereto by
authority of the Board of Trustees.


                                            /s/ Cheryl S. Hilkert 
                                            ------------------------------------
                                            Notary Public
                                            COMMISSION EXPIRES

                [NOTARIAL SEAL APPEARS]
                    

                                        6


<PAGE>   8



STATE OF   ILLINOIS   )
                      ) ss:
COUNTY OF  COOK       )

         On the 22nd day of October 1997, before me personally came
Richard D. Manella, to me known, who, being by me duly sworn, did depose and
say that he/she resides at 211 Willow Pky, Buffalo Grove,IL, 60089 that he/she
is a Vice President of THE FIRST NATIONAL BANK OF CHICAGO, one of the parties
described in and which executed the foregoing instrument, and that he/she signed
his/her name thereto by authority of the Board of Directors.


                                            /s/ Dana McCray
                                            ------------------------------------
                                            Notary Public
                                            COMMISSION EXPIRES

[NOTARIAL SEAL APPEARS]


                                        7


<PAGE>   9



                                                                       Exhibit A

                                 [FACE OF NOTE]

THIS NOTE IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER
REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITORY OR A NOMINEE THEREOF.
THIS NOTE MAY NOT BE TRANSFERRED TO, OR REGISTERED OR EXCHANGED FOR SECURITIES
REGISTERED IN THE NAME OF, ANY PERSON OTHER THAN THE DEPOSITORY OR A NOMINEE
THEREOF AND NO SUCH TRANSFER MAY BE REGISTERED, EXCEPT IN THE LIMITED
CIRCUMSTANCES DESCRIBED IN THE INDENTURE. EVERY SECURITY AUTHENTICATED AND
DELIVERED UPON REGISTRATION OF 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 THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE COMPANY (AS
DEFINED BELOW) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT,
AND ANY CERTIFICATE 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.*

                      LIBERTY PROPERTY LIMITED PARTNERSHIP
                                MEDIUM-TERM NOTE
                                  (Fixed Rate)

<TABLE>
<S>                                 <C>                       <C>
REGISTERED                          CUSIP No.:                PRINCIPAL AMOUNT:  $
No. FXR-_____

ORIGINAL ISSUE DATE:                INTEREST RATE: %          STATED MATURITY DATE:

INTEREST PAYMENT DATE(S):           DEFAULT RATE:   %
[ ] _______ and ________
[ ] Other:

INITIAL REDEMPTION                  INITIAL REDEMPTION        ANNUAL REDEMPTION
DATE:                               PERCENTAGE:  %            PERCENTAGE
                                                              REDUCTION:  %

OPTIONAL REPAYMENT                  REPAYMENT PRICE:  %       [ ] CHECK IF A DISCOUNT NOTE
DATE(S):                                                          Issue Price:  %

SPECIFIED CURRENCY:                 AUTHORIZED DENOMINATION:
[ ] United States dollars           [ ] $1,000 and integral
[ ] Other:                              multiples thereof
                                    [ ] Other:

EXCHANGE RATE                       EXCHANGE RATE:
AGENT:                              U.S. $1.00 =

ADDENDUM ATTACHED:                  OTHER/ADDITIONAL PROVISIONS:

[ ] Yes
[ ] No
</TABLE>
----------------
*  This paragraph applies to global Notes only.


                                       A-1


<PAGE>   10



         Liberty Property Limited Partnership, a Pennsylvania limited 
partnership (the "Company," which term includes any successor entity under the
Indenture hereinafter referred to), for value received, hereby promises to pay
to ____________________________, or registered assigns, upon presentation, the 
principal sum of $__________________________________________, on the Stated 
Maturity Date specified above (or any Redemption Date or Repayment Date,
each as defined on the reverse hereof) (each such Stated Maturity Date,
Redemption Date or Repayment Date being hereinafter referred to as the "Maturity
Date" with respect to the principal repayable on such date) and to pay interest
thereon, at the Interest Rate per annum specified above, until the principal
hereof is paid or duly made available for payment, and (to the extent that the
payment of such interest shall be legally enforceable) at the Default Rate per
annum specified above on any overdue principal, premium and/or interest. The
Company will pay interest in arrears on each Interest Payment Date, if any,
specified above (each, an "Interest Payment Date"), commencing with the first
Interest Payment Date next succeeding the Original Issue Date specified above,
and on the Maturity Date; provided, however, that if the Original Issue Date
occurs between a Record Date (as defined below) and the next succeeding Interest
Payment Date, interest payments will commence on the second Interest Payment
Date next succeeding the Original Issue Date to the holder of this Note on the
Record Date with respect to such second Interest Payment Date. Interest on this
Note will be computed on the basis of a 360-day year of twelve 30-day months.

         Interest on this Note will accrue from, and including, the immediately
preceding Interest Payment Date to which interest has been paid or duly provided
for (or from, and including, the Original Issue Date if no interest has been
paid or duly provided for) to, but excluding, the applicable Interest Payment
Date or the Maturity Date, as the case may be (each, an "Interest Period"). The
interest so payable, and punctually paid or duly provided for, on any Interest
Payment Date will, subject to certain exceptions described herein, be paid to
the person in whose name this Note (or one or more predecessor Notes) is
registered at the close of business on the fifteenth calendar day (whether or
not a Business Day, as defined below) immediately preceding such Interest
Payment Date (the "Record Date"); provided, however, that interest payable on
the Maturity Date will be payable to the person to whom the principal hereof and
premium, if any, hereon shall be payable. Any such interest not so punctually
paid or duly provided for ("Defaulted Interest") will forthwith cease to be
payable to the holder on any Record Date, and shall be paid to the person in
whose name this Note 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 days prior to such
Special Record Date or may be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange on which this Note
may be listed, and upon such notice as may be required by such exchange, all as
more fully provided for in the Indenture.

         Payment of principal, premium, if any, and interest in respect of this
Note due on the Maturity Date will be made in immediately available funds upon
presentation and surrender of this Note (and, with respect to any applicable
repayment of this Note, upon presentation and surrender of this Note and a duly
completed election form as contemplated on the reverse hereof) at the office or
agency maintained by the Company for that purpose in the Borough of Manhattan,
The City of New York, currently the office of the Trustee located at First
National Bank of Chicago, c/o First Chicago Trust Company of New York, 14 Wall
Street, 8th Floor, New York, New York 10005, or at such other paying agency in
the Borough of Manhattan, The City of New York, as the Company may determine;
provided, however, that if the Specified Currency specified above is other than
United States dollars and such payment is to be made in the Specified Currency
in accordance with the provisions set forth below, such payment will be made by
wire transfer of immediately available funds to an account with a bank
designated by the holder hereof at least 15 calendar days prior to the Maturity
Date, provided that such bank has appropriate facilities 


                                       A-2


<PAGE>   11


therefor and that this Note (and, if applicable, a duly completed repayment
election form) is presented and surrendered at the aforementioned office or
agency maintained by the Company in time for the Trustee to make such payment in
such funds in accordance with its normal procedures. Payment of interest due on
any Interest Payment Date other than the Maturity Date will be made at the
aforementioned office or agency maintained by the Company or, at the option of
the Company, by check mailed to the address of the person entitled thereto as
such address shall appear in the Security Register maintained by the Trustee;
provided, however, that a holder of U.S. $10,000,000 (or, if the Specified
Currency is other than United States dollars, the equivalent thereof in the
Specified Currency) or more in aggregate principal amount of Notes (whether
having identical or different terms and provisions) will be entitled to receive
interest payments on any Interest Payment Date other than the Maturity Date by
wire transfer of immediately available funds if appropriate wire transfer
instructions have been received in writing by the Trustee not less than 15
calendar days prior to such Interest Payment Date. Any such wire transfer
instructions received by the Trustee shall remain in effect until revoked by
such holder.

         If any Interest Payment Date or the Maturity Date falls on a day that
is not a Business Day, the required payment of principal, premium, if any,
and/or interest shall be made on the next succeeding Business Day with the same
force and effect as if made on the date such payment was due, and no interest
shall accrue with respect to such payment for the period from and after such
Interest Payment Date or the Maturity Date, as the case may be, to the date of
such payment on the next succeeding Business Day.

         As used herein, "Business Day" means any day, other than a Saturday or
Sunday, that is neither a legal holiday nor a day on which banking institutions
are authorized or required by law, regulation or executive order to close in The
City of New York or Chicago, Illinois; provided, however, that if the Specified
Currency is other than United States dollars, such day is also not a day on
which banking institutions are authorized or required by law, regulation or
executive order to close in the Principal Financial Center (as defined below) of
the country issuing the Specified Currency (unless the Specified Currency is
European Currency Units ("ECU"), in which case such day is also not a day that
appears as an ECU non-settlement day on the display designated as "ISDE" on the
Reuter Monitor Money Rates Service (or a day so designated by the ECU Banking
Association) or, if ECU non-settlement days do not appear on that page (and are
not so designated), a day that is not a day on which payments in ECU cannot be
settled in the international interbank market); provided that, with respect to
Notes as to which LIBOR is an applicable Interest Rate Basis, such day is also a
London Business Day (as defined below). "London Business Day" means any day on
which dealings in the Designated LIBOR Currency (as defined below) are
transacted in the London interbank market. "Principal Financial Center" means
(i) the capital city of the country issuing the Specified Currency (except as
described in the immediately preceding sentence with respect to ECU) or (ii) the
capital city of the country which the Designated LIBOR Currency, if applicable,
relates (or, in the case of ECU, Luxembourg), except, in each case, that with
respect to United States dollars, Australian dollars, Canadian dollars, Deutsche
marks, Dutch guilders, Italian lire, Swiss francs and ECUs, the "Principal
Financial Center" shall be The City of New York, Sydney, Toronto, Frankfurt,
Amsterdam, Milan (solely in the case of clause (i) above), Zurich and
Luxembourg, respectively.

         The Company is obligated to make payments of principal, premium, if
any, and interest in respect of this Note in the Specified Currency (or, if the
Specified Currency is not at the time of such payment legal tender for the
payment of public and private debts, in such other coin or currency of the
country which issued the Specified Currency as at the time of such payment is
legal tender for the payment of such debts). If the Specified Currency is other
than United States dollars, except as provided below, any such amounts so
payable by the Company will be converted by the Exchange Rate Agent specified
above into United States dollars for payment to the holder of this Note.


                                      A-3


<PAGE>   12


         If the Specified Currency is other than United States dollars, the
holder of this Note may elect to receive such amounts in such Specified
Currency. If the holder of this Note shall not have duly made an election to
receive all or a specified portion of any payment of principal, premium, if any,
and/or interest in respect of this Note in the Specified Currency, any United
States dollar amount to be received by the holder of this Note will be based on
the highest bid quotation in The City of New York received by the Exchange Rate
Agent at approximately 11:00 A.M., New York City time, on the second Business
Day preceding the applicable payment date from three recognized foreign exchange
dealers (one of whom may be the Exchange Rate Agent) selected by the Exchange
Rate Agent and approved by the Company for the purchase by the quoting dealer of
the Specified Currency for United States dollars for settlement on such payment
date in the aggregate amount of the Specified Currency payable to all holders of
Notes payable in the Specified Currency who are scheduled to receive United
States dollar payments and at which the applicable dealer commits to execute a
contract. All currency exchange costs will be borne by the holder of this Note
by deductions from such payments. If three such bid quotations are not
available, payments on this Note will be made in the Specified Currency unless
the Specified Currency is not available due to the imposition of exchange
controls or other circumstances beyond the control of the Company.

         If the Specified Currency is other than United States dollars, the
holder of this Note may elect to receive all or a specified portion of any
payment of principal, premium, if any, and/or interest in respect of this Note
in the Specified Currency by submitting a written request for such payment to
the Trustee at its corporate trust office in The City of New York on or prior to
the applicable Record Date or at least 15 calendar days prior to the Maturity
Date, as the case may be. Such written request may be mailed or hand delivered
or sent by cable, telex or other form of facsimile transmission. The holder of
this Note may elect to receive all or a specified portion of all future payments
in the Specified Currency in respect of such principal, premium, if any, and/or
interest and need not file a separate election for each payment. Such election
will remain in effect until revoked by written notice to the Trustee, but
written notice of any such revocation must be received by the Trustee on or
prior to the applicable Record Date or at least 15 calendar days prior to the
Maturity Date, as the case may be.

         If the Specified Currency is other than United States dollars or a
composite currency and the holder of this Note shall have duly made an election
to receive all or a specified portion of any payment of principal, premium, if
any, and/or interest in respect of this Note in the Specified Currency and if
the Specified Currency is not available due to the imposition of exchange
controls or other circumstances beyond the control of the Company, the Company
will be entitled to satisfy its obligations to the holder of this Note by making
such payment in United States dollars on the basis of the Market Exchange Rate
(as defined below), computed by the Exchange Rate Agent, on the second Business
Day prior to such payment date or, if such Market Exchange Rate is not then
available, on the basis of the most recently available Market Exchange Rate, or
as otherwise specified on the face hereof. The "Market Exchange Rate" for the
Specified Currency means the noon dollar buying rate in The City of New York for
cable transfers for the Specified Currency as certified for customs purposes by
(or, if not so certified, as otherwise determined by) the Federal Reserve Bank
of New York. Any payment made under such circumstances in United States dollars
will not constitute an Event of Default (as defined in the Indenture) with
respect to this Note.

         If the Specified Currency is a composite currency and the holder of
this Note shall have duly made an election to receive all or a specified portion
of any payment of principal, premium, if any, and/or interest in respect of this
Note in the Specified Currency and if such composite currency is unavailable due
to the imposition of exchange controls or other circumstances beyond the control
of the Company, then the Company will be entitled to satisfy its obligations to
the holder of this Note by making such payment in United States dollars on the
basis of the equivalent of the composite currency 


                                       A-4


<PAGE>   13

in United States dollars. The component currencies of the composite currency for
this purpose (collectively, the "Component Currencies" and each, a "Component
Currency") shall be the currency amounts that were components of the composite
currency as of the last day on which the composite currency was used. The
equivalent of the composite currency in United States dollars shall be
calculated by aggregating the United States dollar equivalents of the Component
Currencies. The United States dollar equivalent of each of the Component
Currencies shall be determined by the Exchange Rate Agent on the basis of the
Market Exchange Rate on the second Business Day prior to the required payment,
or, if such Market Exchange Rate is not then available, on the basis of the most
recently available Market Exchange Rate for each such Component Currency, or as
otherwise specified on the face hereof.

         If the official unit of any Component Currency is altered by way of
combination or subdivision, the number of units of the currency as a Component
Currency shall be divided or multiplied in the same proportion. If two or more
Component Currencies are consolidated into a single currency, the amounts of
those currencies as Component Currencies shall be replaced by an amount in such
single currency equal to the sum of the amounts of the consolidated Component
Currencies expressed in such single currency. If any Component Currency is
divided into two or more currencies, the amount of the original Component
Currency shall be replaced by the amounts of such two or more currencies, the
sum of which shall be equal to the amount of the original Component Currency.

         All determinations referred to above made by the Exchange Rate Agent
shall be at its sole discretion and shall, in the absence of manifest error, be
conclusive for all purposes and binding on the holder of this Note.

         Reference is hereby made to the further provisions of this Note set
forth on the reverse hereof and, if so specified above on the face hereof, in
the Addendum hereto, which further provisions shall have the same force and
effect as if set forth on the face hereof.

         Notwithstanding any provisions to the contrary contained herein, if the
face of this Note specifies that an Addendum is attached hereto or that
"Other/Additional Provisions" apply to this Note, this Note shall be subject to
the terms set forth in such Addendum or such "Other/Additional Provisions."

         Unless the Certificate of Authentication hereon has been executed by or
on behalf of the Trustee by manual signature, this Note shall not be entitled to
any benefit under the Indenture or be valid or obligatory for any purpose.


                                       A-5


<PAGE>   14




         IN WITNESS WHEREOF, Liberty Property Limited Partnership has caused
this Note to be duly executed by one of its duly authorized officers.

                            LIBERTY PROPERTY LIMITED PARTNERSHIP
                            By: Liberty Property Trust, its sole general partner


                            By:
                               -------------------------------------------------
                               Name:
                               Title:

Dated:____________, 199__ 

ATTEST:

By:
   ----------------------    
   Name:
   Title:

[Seal]


                                       A-6


<PAGE>   15



                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

         This is one of the Securities of the series designated therein referred
to in the within-mentioned Indenture.

THE FIRST NATIONAL BANK OF CHICAGO,
  as Trustee

By                                                  Date:_______________, 199__
  ----------------------------------------------         
         Authorized Signatory




                                       A-7


<PAGE>   16




                                [REVERSE OF NOTE]

                      LIBERTY PROPERTY LIMITED PARTNERSHIP
                                MEDIUM-TERM NOTE
                                  (Fixed Rate)

         This Note is one of a duly authorized series of Securities (the
"Securities") of the Company issued and to be issued under an Indenture, dated
as of October 24, 1997, as amended, modified or supplemented from time to time
(the "Indenture"), between the Company and The First National Bank of Chicago,
as Trustee (the "Trustee," which term includes any successor trustee under the
Indenture), to which Indenture and all indentures supplemental thereto reference
is hereby made for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the holders of
the Securities, and of the terms upon which the Securities are, and are to be,
authenticated and delivered. This Note is one of the series of Securities
designated as "Medium-Term Notes Due Nine Months or More from Date of Issue"
(the "Notes"). All terms used but not defined in this Note or in an Addendum
hereto shall have the meanings assigned to such terms in the Indenture or on the
face hereof, as the case may be.

         This Note is issuable only in registered form without coupons in
minimum denominations of U.S. $1,000 and integral multiples thereof or the
minimum Authorized Denomination specified on the face hereof.

         This Note will not be subject to any sinking fund and, unless otherwise
specified on the face hereof in accordance with the provisions of the following
two paragraphs, will not be redeemable or repayable prior to the Stated Maturity
Date.

         This Note will be subject to redemption at the option of the Company on
any date on or after the Initial Redemption Date, if any, specified on the face
hereof, in whole or from time to time in part in increments of U.S. $1,000 or
the minimum Authorized Denomination (provided that any remaining principal
amount hereof shall be at least U.S. $1,000 or such minimum Authorized
Denomination), at the Redemption Price (as defined below), together with unpaid
interest accrued thereon to the date fixed for redemption (each, a "Redemption
Date"), on written notice given to the holder hereof not more than 60 nor less
than 30 calendar days prior to the Redemption Date and in accordance with the
provisions of the Indenture. The "Redemption Price," if any, shall initially be
the Initial Redemption Percentage specified on the face hereof multiplied by the
unpaid principal amount of this Note to be redeemed. The Initial Redemption
Percentage, if any, shall decline at each anniversary of the Initial Redemption
Date by the Annual Redemption Percentage Reduction, if any, specified on the
face hereof until the Redemption Price is 100% of the unpaid principal amount to
be redeemed. 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
as this Note shall be issued in the name of the holder hereof upon the
presentation and surrender hereof.

         This Note will be subject to repayment by the Company at the option of
the holder hereof on the Optional Repayment Date(s), if any, specified on the
face hereof, in whole or in part in increments of U.S. $1,000 or the minimum
Authorized Denomination (provided that any remaining principal amount hereof
shall be at least U.S. $1,000 or such minimum Authorized Denomination), at a
repayment price equal to 100% of the unpaid principal amount to be repaid,
together with unpaid interest accrued thereon to the date fixed for repayment
(each, a "Repayment Date"). If an Optional Repayment Date is not set 


                                       A-8


<PAGE>   17


forth on the face hereof, this Note will not be repayable at the option of the
holder hereof prior to Maturity. For this Note to be repaid, the Trustee must
receive at its office in the Borough of Manhattan, The City of New York,
referred to on the face hereof, at least 30 days but not more than 60 days prior
to the Repayment Date this Note and the form hereon entitled "Option to Elect
Repayment" duly completed. Exercise of such repayment option by the holder
hereof will be irrevocable. In the event of repayment of this Note in part only,
a new Note of like tenor for the unrepaid portion hereof and otherwise having
the same terms as this Note shall be issued in the name of the holder hereof
upon the presentation and surrender hereof.

         If this Note is a Discount Note as specified on the face hereof, the
amount payable to the holder of this Note in the event of redemption, repayment
or acceleration of maturity of this Note will be equal to the sum of (i) the
Issue Price specified on the face hereof (increased by any accruals of the
Discount, as defined below) and, in the event of any redemption of this Note (if
applicable), multiplied by the Initial Redemption Percentage (as adjusted by the
Annual Redemption Percentage Reduction, if applicable) and (ii) any unpaid
interest on this Note accrued from the Original Issue Date to the Redemption
Date, Repayment Date or date of acceleration of maturity, as the case may be.
The difference between the Issue Price and 100% of the principal amount of this
Note is referred to herein as the "Discount."

         For purposes of determining the amount of Discount that has accrued as
of any Redemption Date, Repayment Date or date of acceleration of maturity of
this Note, such Discount will be accrued so as to cause the yield on the Note to
be constant. The constant yield will be calculated using a 30-day month, 360-
day year convention, a compounding period that, except for the Initial Period
(as defined below), corresponds to the shortest period between Interest Payment
Dates (with ratable accruals within a compounding period), and an assumption
that the maturity of this Note will not be accelerated. If the period from the
Original Issue Date to the initial Interest Payment Date (the "Initial Period")
is shorter than the compounding period for this Note, a proportionate amount of
the yield for an entire compounding period will be accrued. If the Initial
Period is longer than the compounding period, then such period will be divided
into a regular compounding period and a short period, with the short period
being treated as provided in the preceding sentence.

         If an Event of Default, as defined in the Indenture, shall occur and be
continuing, the principal of and premium (if any) and interest on the Notes
either shall automatically become or may be declared due and payable in the
manner and with the effect provided in the Indenture.

         The Indenture contains provisions for defeasance at any time of (a) the
entire indebtedness of the Company on this Note and (b) certain restrictive
covenants and the related defaults and Events of Default applicable to the
Company, in each case, upon compliance by the Company with certain conditions
set forth in the Indenture, which provisions apply to this Note.

         As provided in and subject to the provisions of the Indenture, the
holder of this Note shall not have the right to institute any proceeding with
respect to the Indenture or for the appointment of a receiver or trustee or for
any other remedy hereunder, unless (i) such holder shall have previously given
written notice to the Trustee of a continuing Event of Default with respect to
the Securities of this series, (ii) the holders of not less than 25% in
principal amount of the Securities of this series at the time Outstanding shall
have made written request to the Trustee to institute proceedings in respect of
such Event of Default in its own name as Trustee, (iii) such holder or holders
have offered reasonable indemnity satisfactory to the Trustee against the costs,
expenses and liabilities to be incurred in compliance with such request, (iv)
the Trustee shall have failed to institute any such proceeding for 60 days after
its receipt of such notice, request and offer of indemnity, and (v) the Trustee
shall not have received, during the 60-day period referenced in clause (iv)
above, from the holders of a majority in 


                                       A-9


<PAGE>   18


principal amount of Securities of this series at the time Outstanding in a
direction inconsistent with such request; provided that, no one or more holder
shall have any right in any manner whatever by virtue of, or by availing of, any
provision of the Indenture to affect, disturb or prejudice the rights of any
other holder, or to obtain or to seek to obtain priority or preference over any
other holder or to enforce any right under the Indenture, except in the manner
therein provided and for the equal and ratable benefit of all holders. The
foregoing shall not apply to any suit instituted by the holder of this Note for
the enforcement of any payment of principal hereof (and premium or Make- Whole
Amount, if any) or any interest thereon on or after the respective due dates
expressed herein.

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the holders of the Securities at any time by the
Company and the Trustee with the consent of the holders of not less than a
majority of the aggregate principal amount of all Securities at the time
outstanding and affected thereby. The Indenture also contains provisions
permitting the holders of not less than a majority of the aggregate principal
amount of the outstanding Securities of any series, on behalf of the holders of
all such Securities, to waive compliance by the Company with certain provisions
of the Indenture. Furthermore, provisions in the Indenture permit the holders of
not less than a majority of the aggregate principal amount of the outstanding
Securities of any series, in certain instances, to waive, on behalf of all of
the holders of Securities of such series, certain past defaults under the
Indenture and their consequences. Any such consent or waiver by the holder of
this Note shall be conclusive and binding upon such holder and upon all future
holders of this Note and other Notes issued upon the registration of transfer
hereof or in exchange heretofore or in lieu hereof, whether or not notation of
such consent or waiver is made upon this Note.

         No reference herein to the Indenture and no provision of this Note or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay principal, premium, if any, and interest in
respect of this Note at the times, places and rate or formula, and in the coin
or currency, herein prescribed.

         As provided in the Indenture and subject to certain limitations therein
and herein set forth, the transfer of this Note is registrable in the Security
Register of the Company upon surrender of this Note for registration of transfer
at the office or agency of the Company in any place where the principal hereof
and any premium or interest hereon are payable, duly endorsed by, or accompanied
by a written instrument of transfer in form satisfactory to the Company and the
Security Registrar duly executed by, the holder hereof or by his attorney duly
authorized in writing, and thereupon one or more new Notes, of authorized
denominations and for the same aggregate principal amount, will be issued to the
designated transferee or transferees.

         As provided in the Indenture and subject to certain limitations therein
and herein set forth, this Note is exchangeable for a like aggregate principal
amount of Notes of different authorized denominations but otherwise having the
same terms and conditions, as requested by the holder hereof surrendering the
same.

         No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Note for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
holder in whose name this Note is registered as 

                                      A-10


<PAGE>   19


the owner thereof for all purposes, whether or not this Note be overdue, and
neither the Company, the Trustee nor any such agent shall be affected by notice
to the contrary.

         No recourse under or upon any obligation, covenant or agreement
contained in the Indenture or in this Note, or because of any indebtedness
evidenced thereby or hereby, (including without limitation, any obligation or
indebtedness relating to the principal of, or premium or Make-Whole Amount, if
any, interest or any other amounts due, or claimed to be due, on this Security),
or for any claim based thereon or otherwise in respect thereof, shall be had (i)
against Liberty Property Trust or any other partner of the Company, (ii) against
any person which owns an interest, directly or indirectly, in any partner in the
Company, or (iii) against any promoter, as such or, against any past, present or
future stockholder, partner, officer or director, as such, of the Company or of
any successor, either directly or through the Company or any successor, under
any rule of law, statue 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 of this Note by
the holder thereof and as part of the consideration for the issue of the
Securities of this series. The holder of this Security acknowledges by
acceptance of this Security that its sole remedies under the Indenture for any
Default by the Company in the payment of principal of, or any premium or
Make-Whole Amount, if any, interest or any amounts due, or claimed to be due, on
this Security, or otherwise, are limited to claims against the property of the
Company as provided in Sections 111 and 503 of the Indenture.

         THE INDENTURE AND THE SECURITIES, INCLUDING THIS NOTE, SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAW OF THE STATE OF NEW YORK.

         Pursuant to a recommendation promulgated by the Committee on Uniform
Security Identification Procedures, the Company has caused "CUSIP" numbers to be
printed on the Securities of this series as a convenience to the holders of such
Securities. No representation is made as to the correctness or accuracy of such
CUSIP numbers as printed on the Securities, and reliance may be placed only on
the other identification numbers printed hereon.


                                      A-11


<PAGE>   20



                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this Note, shall be construed as though they were written out in full
according to applicable laws or regulations:

<TABLE>
<S>                 <C>                                             <C>
TEN COMM -          as tenants in common                            UNIF GIFT MIN ACT -
TEN ENT  -          as tenants by the entities                      ______ Custodian ______
JT TEN   -          as joint tenants with right of survivorship     (Cust)           (Minor)
                    and not as tenants in common                    Under Uniform Gifts to Minors
                                                                    Act_____________________
                                                                                   (State)
</TABLE>

Additional abbreviations may also be used though not in the above list.


                              --------------------
                                   ASSIGNMENT


--------------------------------------------------------------------------------
        Please insert social security or other identifying number of assignee.

   FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s)
 unto

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

--------------------------------------------------------------------------------
    (Please print or typewrite name and address including postal zip code of 

assignee) the within Note and all rights thereunder hereby irrevocably 

constituting and appointing ______, attorney to transfer said Note on the books

of the Trustee, with full power of substitution in the premises.

Dated:_____________, 199__

                        ------------------------------------
                        Notice: The signature(s) on this Assignment must
                        correspond with the name(s) as written upon the face of
                        this Note in every particular, without alteration or
                        enlargement or any change whatsoever.

                        Signature must be guaranteed by an "eligible guarantor
                        institution," that is, a bank, stockbroker, savings and
                        loan association or credit union meeting the
                        requirements of the Registrar, which requirements
                        include membership or participation in the Securities
                        Transfer Agents Medallion Program ("STAMP") or such
                        other "signature guarantee program" as may be determined
                        by the Registrar in addition to, or in substitution for,
                        STAMP, all in accordance with the Securities Exchange
                        Act of 1934, as amended.


                                      A-12


<PAGE>   21



                            OPTION TO ELECT REPAYMENT

         The undersigned hereby irrevocably request(s) and instruct(s) the
Company to repay this Note (or portion hereof specified below) pursuant to its
terms at a price equal to 100% of the principal amount to be repaid, together
with unpaid interest accrued hereon to the Repayment Date, to the undersigned,
at______________________________________________________________________________
         (Please print or typewrite name and address of the undersigned)

         For this Note to be repaid, the Trustee must receive at its corporate
trust office in the Borough of Manhattan, The City of New York, not more than 60
nor less than 30 calendar days prior to the Repayment Date, this Note with this
"Option to Elect Repayment" form duly completed.

         If less than the entire principal amount of this Note is to be repaid,
specify the portion hereof (which shall be increments of U.S. $1,000 (or, if the
Specified Currency is other than United States dollars, the minimum Authorized
Denomination specified on the face hereof)) which the holder elects to have
repaid and specify the denomination or denominations (which shall be an
Authorized Denomination) of the Notes to be issued to the holder for the portion
of this Note not being repaid (in the absence of any such specification, one
such Note will be issued for the portion not being repaid).


Principal Amount to be Repaid:  $

Date:

                                 ------------------------------------ 
                                 Notice: The signature(s) on thisOption to Elect
                                 Repayment must correspond with the name(s) as
                                 written upon the face of this Note in every 
                                 particular, without alteration or enlargement 
                                 or any change whatsoever.


                                      A-13


<PAGE>   22



                                                                       Exhibit B

                                 [FACE OF NOTE]

THIS NOTE IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER
REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITORY OR A NOMINEE THEREOF.
THIS NOTE MAY NOT BE TRANSFERRED TO, OR REGISTERED OR EXCHANGED FOR SECURITIES
REGISTERED IN THE NAME OF, ANY PERSON OTHER THAN THE DEPOSITORY OR A NOMINEE
THEREOF AND NO SUCH TRANSFER MAY BE REGISTERED, EXCEPT IN THE LIMITED
CIRCUMSTANCES DESCRIBED IN THE INDENTURE. EVERY SECURITY AUTHENTICATED AND
DELIVERED UPON REGISTRATION OF 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 THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE COMPANY (AS
DEFINED BELOW) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT,
AND ANY CERTIFICATE 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.*

                      LIBERTY PROPERTY LIMITED PARTNERSHIP
                                MEDIUM-TERM NOTE
                                 (Floating Rate)
<TABLE>
<S>                     <C>                          <C> 
REGISTERED              CUSIP No.:                   PRINCIPAL AMOUNT: $
No. FLR-____


INTEREST RATE BASIS     ORIGINAL ISSUE DATE:         STATED MATURITY DATE:
OR BASES:

IF LIBOR:                                                 IF CMT RATE:
       [ ] LIBOR Reuters                                  Designated CMT Telerate Page:
       [ ] LIBOR Telerate                                 If Telerate Page 7052:
       [ ] Designated LIBOR Currency                               [ ] Weekly Average
       [ ] Designated LIBOR Page:                                  [ ] Monthly Average
       [ ] Reuters Page:                                  Designated CMT Maturity Index:
       [ ] Telerate Page:

INITIAL INTEREST RATE: %
INITIAL INTEREST RESET DATE:
INTEREST RESET PERIOD:
INTEREST RESET DATE(S):
INTEREST PAYMENT DATE(S):
INDEX MATURITY:
</TABLE>


                                       B-1


<PAGE>   23



SPREAD (PLUS OR MINUS):
SPREAD MULTIPLIER:
MINIMUM INTEREST RATE: %
MAXIMUM INTEREST RATE:  %
INITIAL REDEMPTION DATE:
INITIAL REDEMPTION PERCENTAGE:  %
ANNUAL REDEMPTION PERCENTAGE REDUCTION:  %
OPTIONAL REPAYMENT DATE(S):
REPAYMENT PRICE:  %
[ ] CHECK IF A DISCOUNT NOTE ISSUE PRICE:  %

 INTEREST CATEGORY:                   DAY COUNT CONVENTION:
 [ ] Regular Floating Rate Note       [ ]      30/360 for the period from
 [ ] Floating Rate/Fixed Rate Note             ___________ to _________
     Fixed Rate Commencement Date:    [ ]      Actual/360 for the period from
     Fixed Interest Rate:   %                  ___________ to _________
 [ ] Inverse Floating Rate Note       [ ]      Actual/Actual for the period from
     Fixed Interest Rate:   %                  ___________ to _________

                                      Applicable Interest Rate Basis:

SPECIFIED CURRENCY:                   AUTHORIZED DENOMINATION:
[ ] United States dollars             [ ] $1,000 and integral multiples thereof
[ ] Other:                            [ ] Other:

CALCULATION AGENT:

EXCHANGE RATE AGENT: EXCHANGE RATE:       DEFAULT RATE:  %
                     U.S. $1.00 =

ADDENDUM ATTACHED: ISSUE PRICE:
[ ] Yes
[ ] No

AGENT'S DISCOUNT OR COMMISSION:

OTHER/ADDITIONAL PROVISIONS:



-----------------------
* This paragraph applies to global Notes only.


                                       B-2


<PAGE>   24

         Liberty Property Limited Partnership, a Pennsylvania limited
partnership (the "Company," which term includes any successor entity under the
Indenture hereinafter referred to), for value received, hereby promises to pay
to _____________________________________________________________________ , or
registered assigns, upon presentation, the principal sum of
$___________________________________________, on the Stated Maturity Date
specified above (or any Redemption Date or Repayment Date, each as defined on
the reverse hereof) (each such Stated Maturity Date, Redemption Date or
Repayment Date being hereinafter referred to as the "Maturity Date" with respect
to the principal repayable on such date) and to pay interest thereon, at a rate
per annum equal to the Initial Interest Rate specified above until the Initial
Interest Reset Date specified above and thereafter at a rate determined in
accordance with the provisions specified above and on the reverse hereof or in
an Addendum hereto with respect to one or more Interest Rate Bases specified
above until the principal hereof is paid or duly made available for payment, and
(to the extent that the payment of such interest shall be legally enforceable)
at the Default Rate per annum specified above on any overdue principal, premium
and/or interest. The Company will pay interest in arrears on each Interest
Payment Date, if any, specified above (each, an "Interest Payment Date"),
commencing with the first Interest Payment Date next succeeding the Original
Issue Date specified above, and on the Maturity Date; provided, however, that if
the Original Issue Date occurs between a Record Date (as defined below) and the
next succeeding Interest Payment Date, interest payments will commence on the
second Interest Payment Date next succeeding the Original Issue Date to the
holder of this Note on the Record Date with respect to such second Interest
Payment Date.

         Interest on this Note will accrue from, and including, the immediately
preceding Interest Payment Date to which interest has been paid or duly provided
for (or from, and including, the Original Issue Date if no interest has been
paid or duly provided for) to, but excluding, the applicable Interest Payment
Date or the Maturity Date, as the case may be (each, an "Interest Period"). The
interest so payable, and punctually paid or duly provided for, on any Interest
Payment Date will, subject to certain exceptions described herein, be paid to
the person in whose name this Note (or one or more predecessor Notes) is
registered at the close of business on the fifteenth calendar day (whether or
not a Business Day, as defined below) immediately preceding such Interest
Payment Date (the "Record Date"); provided, however, that interest payable on
the Maturity Date will be payable to the person to whom the principal hereof and
premium, if any, hereon shall be payable. Any such interest not so punctually
paid or duly provided for ("Defaulted Interest") will forthwith cease to be
payable to the holder on any Record Date, and shall be paid to the person in
whose name this Note 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 days prior to such
Special Record Date or may be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange on which this Note
may be listed, and upon such notice as may be required by such exchange, all as
more fully provided for in the Indenture.

         Payment of principal, premium, if any, and interest in respect of this
Note due on the Maturity Date will be made in immediately available funds upon
presentation and surrender of this Note (and, with respect to any applicable
repayment of this Note, upon presentation and surrender of this Note and a duly
completed election form as contemplated on the reverse hereof) at the office or
agency maintained by the Company for that purpose in the Borough of Manhattan,
The City of New York, currently the office of the Trustee located at First
National Bank of Chicago, c/o First Chicago Trust Company of New York, 14 Wall
Street, 8th Floor, New York, New York 10005, or at such other paying agency in
the Borough of Manhattan, The City of New York, as the Company may determine;
provided, however, that if the Specified Currency specified above is other than
United States dollars and such payment is to be made in the Specified Currency
in accordance with the provisions set forth below, such payment will be made by
wire transfer of immediately available funds to an account with a bank
designated by the holder hereof


                                       B-3

<PAGE>   25

at least 15 calendar days prior to the Maturity Date, provided that such bank
has appropriate facilities therefor and that this Note (and, if applicable, a
duly completed repayment election form) is presented and surrendered at the
aforementioned office or agency maintained by the Company in time for the
Trustee to make such payment in such funds in accordance with its normal
procedures. Payment of interest due on any Interest Payment Date other than the
Maturity Date will be made at the aforementioned office of agency maintained by
the Company or, at the option of the Company, by check mailed to the address of
the person entitled thereto as such address shall appear in the Security
Register maintained by the Trustee; provided, however, that a holder of U.S.
$10,000,000 (or, if the Specified Currency is other than United States dollars,
the equivalent thereof in the Specified Currency) or more in aggregate principal
amount of Notes (whether having identical or different terms and provisions)
will be entitled to receive interest payments on any Interest Payment Date other
than the Maturity Date by wire transfer of immediately available funds if
appropriate wire transfer instructions have been received in writing by the
Trustee not less than 15 calendar days prior to such Interest Payment Date. Any
such wire transfer instructions received by the Trustee shall remain in effect
until revoked by such holder.

         If any Interest Payment Date other than the Maturity Date would
otherwise be a day that is not a Business Day, such Interest Payment Date shall
be postponed to the next succeeding Business Day, except that if LIBOR is an
applicable Interest Rate Basis and such Business Day falls in the next
succeeding calendar month, such Interest Payment Date shall be the immediately
preceding Business Day, and if the Maturity Date falls on a day that is not a
Business Day, the required payment of principal, premium, if any, and/or
interest shall be made on the next succeeding Business Day, each with the same
force and effect as if made on the date such payment was due, and no interest
shall accrue with respect to such payment for the period from and after such
Interest Payment Date or the Maturity Date, as the case may be, to the date of
such payment on the next succeeding Business Day.

         As used herein, "Business Day" means any day, other than a Saturday or
Sunday, that is neither a legal holiday nor a day on which banking institutions
are authorized or required by law, regulation or executive order to close in The
City of New York or Chicago, Illinois; provided, however, that if the Specified
Currency is other than United States dollars, such day is also not a day on
which banking institutions are authorized or required by law, regulation or
executive order to close in the Principal Financial Center (as defined below) of
the country issuing the Specified Currency (unless the Specified Currency is
European Currency Units ("ECU"), in which case such day is also not a day that
appears as an ECU non-settlement day on the display designated as "ISDE" on the
Reuter Monitor Money Rates Service (or a day so designated by the ECU Banking
Association) or, if ECU non-settlement days do not appear on that page (and are
not so designated), a day that is not a day on which payments in ECU cannot be
settled in the international interbank market); provided that, with respect to
Notes as to which LIBOR is an applicable Interest Rate Basis, such day is also a
London Business Day (as defined below). "London Business Day" means any day on
which dealings in the Designated LIBOR Currency (as defined below) are
transacted in the London interbank market. "Principal Financial Center" means
(i) the capital city of the country issuing the Specified Currency (except as
described in the immediately preceding sentence with respect to ECU) or (ii) the
capital city of the country which the Designated LIBOR Currency, if applicable,
relates (or, in the case of ECU, Luxembourg), except, in each case, that with
respect to United States dollars, Australian dollars, Canadian dollars, Deutsche
marks, Dutch guilders, Italian lire, Swiss francs and ECUs, the "Principal
Financial Center" shall be The City of New York, Sydney, Toronto, Frankfurt,
Amsterdam, Milan (solely in the case of clause (i) above), Zurich and
Luxembourg, respectively.

         The Company is obligated to make payments of principal, premium, if
any, and interest in respect of this Note in the Specified Currency (or, if the
Specified Currency is not at the time of such payment legal tender for the
payment of public and private debts, in such other coin or currency of the
country


                                       B-4

<PAGE>   26

which issued the Specified Currency as at the time of such payment is legal
tender for the payment of such debts). If the Specified Currency is other than
United States dollars, except as provided below, any such amounts so payable by
the Company will be converted by the Exchange Rate Agent specified above into
United States dollars for payment to the holder of this Note.

         If the Specified Currency is other than United States dollars, the
holder of this Note may elect to receive such amounts in such Specified
Currency. If the holder of this Note shall not have duly made an election to
receive all or a specified portion of any payment of principal, premium, if any,
and/or interest in respect of this Note in the Specified Currency, any United
States dollar amount to be received by the holder of this Note will be based on
the highest bid quotation in The City of New York received by the Exchange Rate
Agent at approximately 11:00 A.M., New York City time, on the second Business
Day preceding the applicable payment date from three recognized foreign exchange
dealers (one of whom may be the Exchange Rate Agent) selected by the Exchange
Rate Agent and approved by the Company for the purchase by the quoting dealer of
the Specified Currency for United States dollars for settlement on such payment
date in the aggregate amount of the Specified Currency payable to all holders of
Notes payable in the Specified Currency who are scheduled to receive United
States dollar payments and at which the applicable dealer commits to execute a
contract. All currency exchange costs will be borne by the holder of this Note
by deductions from such payments. If three such bid quotations are not
available, payments on this Note will be made in the Specified Currency unless
the Specified Currency is not available due to the imposition of exchange
controls or other circumstances beyond the control of the Company.

         If the Specified Currency is other than United States dollars, the
holder of this Note may elect to receive all or a specified portion of any
payment of principal, premium, if any, and/or interest in respect of this Note
in the Specified Currency by submitting a written request for such payment to
the Trustee at its corporate trust office in The City of New York on or prior to
the applicable Record Date or at least 15 calendar days prior to the Maturity
Date, as the case may be. Such written request may be mailed or hand delivered
or sent by cable, telex or other form of facsimile transmission. The holder of
this Note may elect to receive all or a specified portion of all future payments
in the Specified Currency in respect of such principal, premium, if any, and/or
interest and need not file a separate election for each payment. Such election
will remain in effect until revoked by written notice to the Trustee, but
written notice of any such revocation must be received by the Trustee on or
prior to the applicable Record Date or at least 15 calendar days prior to the
Maturity Date, as the case may be.

         If the Specified Currency is other than United States dollars or a
composite currency and the holder of this Note shall have duly made an election
to receive all or a specified portion of any payment of principal, premium, if
any, and/or interest in respect of this Note in the Specified Currency and if
the Specified Currency is not available due to the imposition of exchange
controls or other circumstances beyond the control of the Company, the Company
will be entitled to satisfy its obligations to the holder of this Note by making
such payment in United States dollars on the basis of the Market Exchange Rate
(as defined below), computed by the Exchange Rate Agent, on the second Business
Day prior to such payment date or, if such Market Exchange Rate is not then
available, on the basis of the most recently available Market Exchange Rate or
as otherwise specified on the face hereof. The "Market Exchange Rate" for the
Specified Currency means the noon dollar buying rate in The City of New York for
cable transfers for the Specified Currency as certified for customs purposes by
(or, if not so certified, as otherwise determined by) the Federal Reserve Bank
of New York. Any payment made under such circumstances in United States dollars
will not constitute an Event of Default (as defined in the Indenture) with
respect to this Note.


                                       B-5

<PAGE>   27

         If the Specified Currency is a composite currency and the holder of
this Note shall have duly made an election to receive all or a specified portion
of any payment of principal, premium, if any, and/or interest in respect of this
Note in the Specified Currency and if such composite currency is unavailable due
to the imposition of exchange controls or other circumstances beyond the control
of the Company, then the Company will be entitled to satisfy its obligations to
the holder of this Note by making such payment in United States dollars on the
basis of the equivalent of the composite currency in United States dollars. The
component currencies of the composite currency for this purpose (collectively,
the "Component Currencies" and each, a "Composite Currency") shall be the
currency amounts that were components of the composite currency as of the last
day on which the composite currency was used. The equivalent of the composite
currency in United States dollars shall be calculated by aggregating the United
States dollar equivalents of the Component Currencies. The United States dollar
equivalent of each of the Component Currencies shall be determined by the
Exchange Rate Agent on the basis of the Market Exchange Rate on the second
Business Day prior to the required payment, or, if such Market Exchange Rate is
not then available, on the basis of the most recently available Market Exchange
Rate for each such Component Currency, or as otherwise specified on the face
hereof.

         If the official unit of any Component Currency is altered by way of
combination or subdivision, the number of units of the currency as a Component
Currency shall be divided or multiplied in the same proportion. If two or more
Component Currencies are consolidated into a single currency, the amounts of
those currencies as Component Currencies shall be replaced by an amount in such
single currency equal to the sum of the amounts of the consolidated Component
Currencies expressed in such single currency. If any Component Currency is
divided into two or more currencies, the amount of the original Component
Currency shall be replaced by the amounts of such two or more currencies, the
sum of which shall be equal to the amount of the original Component Currency.

         All determinations referred to above made by the Exchange Rate Agent
shall be at its sole discretion and shall, in the absence of manifest error, be
conclusive for all purposes and binding on the holder of this Note.

         Reference is hereby made to the further provisions of this Note set
forth on the reverse hereof and, if so specified above on the face hereof, in
the Addendum hereto, which further provisions shall have the same force and
effect as if set forth on the face hereof.

         Notwithstanding any provisions to the contrary contained herein, if the
face of this Note specifies that an Addendum is attached hereto or that
"Other/Additional Provisions" apply to this Note, this Note shall be subject to
the terms set forth in such Addendum or such "Other/Additional Provisions."

         Unless the Certificate of Authentication hereon has been executed by or
on behalf of the Trustee by manual signature, this Note shall not be entitled to
any benefit under the Indenture or be valid or obligatory for any purpose.


                                       B-6

<PAGE>   28

         IN WITNESS WHEREOF, Liberty Property Limited Partnership has caused
this Note to be duly executed by one of its duly authorized officers.

                           LIBERTY PROPERTY LIMITED PARTNERSHIP
                           By: Liberty Property Trust, its sole general partner

                           By: 
                              -------------------------------------------------
                              Name:
                              Title:

Dated:

ATTEST:

By: -----------------------
    Name:
    Title:

[Seal]



                                       B-7

<PAGE>   29

                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

         This is one of the Securities of the series designated therein referred
to in the within-mentioned Indenture.

THE FIRST NATIONAL BANK OF CHICAGO,
     as Trustee

By                                                 Date:_______________, 199__
  ---------------------------------------                  
          Authorized Signatory


                                       B-8

<PAGE>   30

                                [REVERSE OF NOTE]

                      LIBERTY PROPERTY LIMITED PARTNERSHIP
                                MEDIUM-TERM NOTE
                                 (Floating Rate)

         This Note is one of a duly authorized series of Securities (the
"Securities") of the Company issued and to be issued under an Indenture, dated
as of October 24, 1997, as amended, modified or supplemented from time to time
(the "Indenture"), between the Company and The First National Bank of Chicago,
as Trustee (the "Trustee", which term includes any successor trustee under the
Indenture), to which Indenture and all indentures supplemental thereto reference
is hereby made for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the holders of
the Securities, and of the terms upon which the Securities are, and are to be,
authenticated and delivered. This Note is one of the series of Securities
designated as "Medium-Term Notes Due Nine Months or More from Date of Issue"
(the "Notes"). All terms used but not defined in this Note or in an Addendum
hereto shall have the meanings assigned to such terms in the Indenture or on the
face hereof, as the case may be.

         This Note is issuable only in registered form without coupons in
minimum denominations of U.S. $1,000 and integral multiples thereof or the
minimum Authorized Denomination specified on the face hereof.

         This Note will not be subject to any sinking fund and, unless otherwise
specified on the face hereof in accordance with the provisions of the following
two paragraphs, will not be redeemable or repayable prior to the Stated Maturity
Date.

         This Note will be subject to redemption at the option of the Company on
any date on or after the Initial Redemption Date, if any, specified on the face
hereof, in whole or from time to time in part in increments of U.S. $1,000 or
the minimum Authorized Denomination (provided that any remaining principal
amount hereof shall be at least U.S. $1,000 or such minimum Authorized
Denomination), at the Redemption Price (as defined below), together with unpaid
interest accrued thereon to the date fixed for redemption (each, a "Redemption
Date"), on written notice given to the holder hereof not more than 60 nor less
than 30 calendar days prior to the Redemption Date and in accordance with the
provisions of the Indenture. The "Redemption Price," if any, shall initially be
the Initial Redemption Percentage specified on the face hereof multiplied by the
unpaid principal amount of this Note to be redeemed. The Initial Redemption
Percentage, if any, shall decline at each anniversary of the Initial Redemption
Date by the Annual Redemption Percentage Reduction, if any, specified on the
face hereof until the Redemption Price is 100% of the unpaid principal amount to
be redeemed. 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
as this Note shall be issued in the name of the holder hereof upon the
presentation and surrender hereof.

         This Note will be subject to repayment by the Company at the option of
the holder hereof on the Optional Repayment Date(s), if any, specified on the
face hereof, in whole or in part in increments of U.S. $1,000 or the minimum
Authorized Denomination (provided that any remaining principal amount hereof
shall be at least U.S. $1,000 or such minimum Authorized Denomination), at a
repayment price equal to 100% of the unpaid principal amount to be repaid,
together with unpaid interest accrued thereon to the date fixed for repayment
(each, a "Repayment Date"). If an Optional Repayment Date is not set


                                       B-9

<PAGE>   31

forth on the face hereof, this Note will not be repayable at the option of the
holder hereof prior to Maturity. For this Note to be repaid, the Trustee must
receive at its office in the Borough of Manhattan, the City of New York,
referred to on the face hereof, at least 30 days but not more than 60 days prior
to the Repayment Date this Note and the form hereon entitled "Option to Elect
Repayment" duly completed. Exercise of such repayment option by the holder
hereof will be irrevocable. In the event of repayment of this Note in part only,
a new Note of like tenor for the unrepaid portion hereof and otherwise having
the same terms as this Note shall be issued in the name of the holder hereof
upon the presentation and surrender hereof.

         If this Note is a Discount Note as specified on the face hereof, the
amount payable to the holder of this Note in the event of redemption, repayment
or acceleration of maturity of this Note will be equal to the sum of (i) the
Issue Price specified on the face hereof (increased by any accruals of the
Discount, as defined below) and, in the event of any redemption of this Note (if
applicable), multiplied by the Initial Redemption Percentage (as adjusted by the
Annual Redemption Percentage Reduction, if applicable) and (ii) any unpaid
interest on this Note accrued from the Original Issue Date to the Redemption
Date, Repayment Date or date of acceleration of maturity, as the case may be.
The difference between the Issue Price and 100% of the principal amount of this
Note is referred to herein as the "Discount."

         For purposes of determining the amount of Discount that has accrued as
of any Redemption Date, Repayment Date or date of acceleration of maturity of
this Note, such Discount will be accrued so as to cause an assumed yield on the
Note to be constant. The assumed constant yield will be calculated using a
30-day month, 360-day year convention, a compounding period that, except for the
Initial Period (as defined below), corresponds to the shortest period between
Interest Payment Dates (with ratable accruals within a compounding period), a
coupon rate equal to the initial coupon rate applicable to this Note and an
assumption that the maturity of this Note will not be accelerated. If the period
from the Original Issue Date to the initial Interest Payment Date (the "Initial
Period") is shorter than the compounding period for this Note, a proportionate
amount of the yield for an entire compounding period will be accrued. If the
Initial Period is longer than the compounding period, then such period will be
divided into a regular compounding period and a short period, with the short
period being treated as provided in the preceding sentence.

         The interest rate borne by this Note shall be determined as follows:

                  (i)  Unless the Interest Category of this Note is specified on
the face hereof as a "Floating Rate/Fixed Rate Note" or an "Inverse Floating
Rate Note" or as having an Addendum attached or having "Other/Additional
Provisions," in each case relating to different interest rate formula, this Note
shall be designated as a "Regular Floating Rate Note" and, except as set forth
below or specified on the face hereof or in an Addendum hereto, shall bear
interest at the rate determined by reference to the applicable Interest Rate
Basis or Bases (a) plus or minus the Spread, if any, and/or (b) multiplied by
the Spread Multiplier, if any, in each case as specified on the face hereof.
Commencing on the Initial Interest Reset Date, the rate at which interest on
this Note shall be payable shall be reset as of each Interest Reset Date
specified on the face hereof; provided, however, that the interest rate in
effect for the period, if any, from the Original Issue Date to the Initial
Interest Reset Date shall be the Initial Interest Rate.

                  (ii) If the Interest Category of this Note is specified on the
face hereof as a "Floating Rate/Fixed Rate Note," then, except as described
below or specified on the face hereof or in an Addendum hereto, this Note shall
bear interest at the rate determined by reference to the applicable Interest
Rate Basis or Bases (a) plus or minus the Spread, if any, and/or (b) multiplied
by the Spread Multiplier, if any. Commencing on the Initial Interest Reset Date,
the rate at which interest on this Note


                                      B-10

<PAGE>   32

shall be payable shall be reset as of each Interest Reset Date; provided,
however, that (y) the interest rate in effect for the period, if any, from the
Original Issue Date to the Initial Interest Reset Date shall be the Initial
Interest Rate and (z) the interest rate in effect for the period commencing on
the Fixed Rate Commencement Date specified on the face hereof to the Maturity
Date shall be the Fixed Interest Rate specified on the face hereof or, if no
such Fixed Interest Rate is specified, the interest rate in effect hereon on the
day immediately preceding the Fixed Rate Commencement Date.

                  (iii) If the Interest Category of this Note is specified on 
the face hereof as an "Inverse Floating Rate Note," then, except as set forth
below or specified on the face hereof or in an Addendum hereto, this Note shall
bear interest at the Fixed Interest Rate minus the rate determined by reference
to the applicable Interest Rate Basis or Bases (a) plus or minus the Spread, if
any, and/or (b) multiplied by the Spread Multiplier, if any; provided, however,
that, unless otherwise specified on the face hereof or in an Addendum hereto,
the interest rate hereon shall not be less than zero. Commencing on the Initial
Interest Reset Date, the rate at which interest on this Note shall be payable
shall be reset as of each Interest Reset Date; provided, however, that the
interest rate in effect for the period, if any, from the Original Issue Date to
the Initial Interest Reset Date shall be the Initial Interest Rate.

         Except as set forth above or specified on the face hereof or in an
Addendum hereto, the interest rate in effect on each day shall be (i) if such
day is an Interest Reset Date, the interest rate determined as of the Interest
Determination Date (as defined below) immediately preceding such Interest Reset
Date or (ii) if such day is not an Interest Reset Date, the interest rate
determined as of the Interest Determination Date immediately preceding the most
recent Interest Reset Date. If any Interest Reset Date would otherwise be a day
that is not a Business Day, such Interest Reset Date shall be postponed to the
next succeeding Business Day, except that if LIBOR is an applicable Interest
Rate Basis and such Business Day falls in the next succeeding calendar month,
such Interest Reset Date shall be the immediately preceding Business Day. In
addition, if the Treasury Rate is an applicable Interest Rate Basis and the
Interest Determination Date would otherwise fall on an Interest Reset Date, then
such Interest Reset Date will be postponed to the next succeeding Business Day.

         The interest rate applicable to each Interest Reset Period commencing
on the related Interest Reset Date will be determined by the Calculation Agent
as of the applicable Interest Determination Date and will be calculated by the
Calculation Agent on or prior to the Calculation Date (as defined below), except
with respect to LIBOR and the 11th District Cost of Funds Rate, which will be
calculated on such Interest Determination Date. The "Interest Determination
Date" with respect to the CD Rate, the CMT Rate, the Commercial Paper Rate, the
Federal Funds Rate, the Kenny Rate and the Prime Rate will be the second
Business Day immediately preceding the applicable Interest Reset Date; the
"Interest Determination Date" with respect to the 11th District Cost of Funds
Rate shall be the last working day of the month immediately preceding the
applicable Interest Reset Date on which the Federal Home Loan Bank of San
Francisco (the "FHLB of San Francisco") publishes the Index (as defined below);
and the "Interest Determination Date" with respect to LIBOR shall be the second
London Business Day immediately preceding the applicable Interest Reset Date,
unless the Designated LIBOR Currency is British pounds sterling, in which case
the "Interest Determination Date" will be the applicable Interest Reset Date.
The "Interest Determination Date" with respect to the Treasury Rate shall be the
day in the week in which the applicable Interest Reset Date falls on which day
Treasury Bills (as defined below) are normally auctioned (Treasury Bills are
normally sold at an auction held on Monday of each week, unless that day is a
legal holiday, in which case the auction is normally held on the following
Tuesday, except that such auction may be held on the preceding Friday);
provided, however, that if an auction is held on the Friday of the week
preceding the applicable Interest Reset Date, the "Interest Determination Date"
shall be such preceding Friday, provided, further, that if the Interest
Determination Date would otherwise fall on an Interest Reset Date, then such
Interest Reset Date shall be postponed to the next succeeding Business Day.


                                      B-11

<PAGE>   33

If the interest rate of this Note is determined with reference to two or more
Interest Rate Bases specified on the face hereof, the "Interest Determination
Date" pertaining to this Note shall be the most recent Business Day which is at
least two Business Days prior to the applicable Interest Reset Date on which
each Interest Rate Basis is determinable. Each Interest Rate Basis shall be
determined as of such date, and the applicable interest rate shall take effect
on the applicable Interest Reset Date.

         Unless otherwise specified on the face hereof or in an Addendum hereto,
the rate with respect to each Interest Rate Basis will be determined in
accordance with the following provisions.

         CD Rate. If an Interest Rate Basis for this Note is specified on the
face hereof as the CD Rate, the CD Rate shall be determined as of the applicable
Interest Determination Date (a "CD Rate Interest Determination Date") as the
rate on such date for negotiable United States dollar certificates of deposit
having the Index Maturity specified on the face hereof as published by the Board
of Governors of the Federal Reserve System in "Statistical Release H.15(519),
Selected Interest Rates" or any successor publication ("H.15(519)") under the
heading "CDs (Secondary Market)", or, if not published by 3:00 P.M., New York
City time, on the related Calculation Date, the rate on such CD Rate Interest
Determination Date for negotiable United States dollar certificates of deposit
of the Index Maturity as published by the Federal Reserve Bank of New York in
its daily statistical release "Composite 3:30 P.M. Quotations for United States
Government Securities" or any successor publication ("Composite Quotations")
under the heading "Certificates of Deposit". If such rate is not yet published
in either H.15(519) or Composite Quotations by 3:00 P.M., New York City time, on
the related Calculation Date, then the CD Rate on such CD Rate Interest
Determination Date will be calculated by the Calculation Agent specified on the
face hereof and will be the arithmetic mean of the secondary market offered
rates as of 10:00 A.M., New York City time, on such CD Rate Interest
Determination Date, of three leading nonbank dealers in negotiable United States
dollar certificates of deposit in The City of New York selected by the
Calculation Agent for negotiable United States dollar certificates of deposit of
major United States money center banks in the market for negotiable United
States dollar certificates of deposit with a remaining maturity closest to the
Index Maturity in an amount that is representative for a single transaction in
that market at that time; provided, however, that if the dealers so selected by
the Calculation Agent are not quoting as mentioned in this sentence, the CD Rate
determined as of such CD Rate Interest Determination Date will be the CD Rate in
effect on such CD Rate Interest Determination Date.

         CMT Rate. If an Interest Rate Basis for this Note is specified on the
face hereof as the CMT rate, the CMT Rate shall be determined as of the
applicable Interest Determination Date (a "CMT Rate Interest Determination
Date") as the rate displayed on the Designated CMT Telerate Page (as defined
below) under the caption "...Treasury Constant Maturities...Federal Reserve
Board Release H.15...Mondays Approximately 3:45 P.M.," under the column for the
Designated CMT Maturity Index (as defined below) for (i) if the Designated CMT
Telerate Page is 7055, the rate on such CMT Rate Interest Determination Date and
(ii) if the Designated CMT Telerate Page is 7052, the weekly or monthly average,
as specified on the face hereof, for the week or month, as applicable, ended
immediately preceding the week or month, as applicable, in which the related CMT
Rate Interest Determination Date occurs. If such rate is no longer displayed on
the relevant page or is not displayed by 3:00 P.M., New York City time, on the
related Calculation Date, then the CMT Rate for such CMT Rate Interest
Determination Date will be such treasury constant maturity rate for the
Designated CMT Maturity Index as published in H.15(519). If such rate is no
longer published or is not published by 3:00 P.M., New York City time, on the
related Calculation Date, then the CMT Rate on such CMT Rate Interest
Determination Date will be such treasury constant maturity rate for the
Designated CMT Maturity Index (or other United States Treasury rate for the
Designated CMT Maturity Index) for the CMT Rate Interest Determination Date with
respect to such Interest Reset Date as may then be published by either the Board


                                      B-12

<PAGE>   34

of Governors of the Federal Reserve System or the United States Department of
the Treasury that the Calculation Agent determines to be comparable to the rate
formerly displayed on the Designated CMT Telerate Page and published in
H.15(519). If such information is not provided by 3:00 P.M., New York City time,
on the related Calculation Date, then the CMT Rate on the CMT Rate Interest
Determination Date will be calculated by the Calculation Agent and will be a
yield to maturity, based on the arithmetic mean of the secondary market offered
rates as of approximately 3:30 P.M., New York City time, on such CMT Rate
Interest Determination Date reported, according to their written records, by
three leading primary United States government securities dealers in The City of
New York (each, a "Reference Dealer") selected by the Calculation Agent (from
five such Reference Dealers selected by the Calculation Agent and eliminating
the highest quotation (or, in the event of equality, one of the highest) and the
lowest quotation (or, in the event of equality, one of the lowest)), for the
most recently issued direct noncallable fixed rate obligations of the United
States ("Treasury Notes") with an original maturity of approximately the
Designated CMT Maturity Index and a remaining term to maturity of not less than
such Designated CMT Maturity Index minus one year. If the Calculation Agent is
unable to obtain three such Treasury Note quotations, the CMT Rate on such CMT
Rate Interest Determination Date will be calculated by the Calculation Agent and
will be a yield to maturity based on the arithmetic mean of the secondary market
offered rates as of approximately 3:30 P.M., New York City time, on such CMT
Rate Interest Determination Date of three Reference Dealers in The City of New
York (from five such Reference Dealers selected by the Calculation Agent and
eliminating the highest quotation (or, in the event of equality, one of the
highest) and the lowest quotation (or, in the event of equality, one of the
lowest)), for Treasury Notes with an original maturity of the number of years
that is the next highest to the Designated CMT Maturity Index and a remaining
term to maturity closest to the Designated CMT Maturity Index and in an amount
of at least U.S. $100 million. If three or four (and not five) of such Reference
Dealers are quoting as described above, then the CMT Rate will be based on the
arithmetic mean of the offered rates obtained and neither the highest nor the
lowest of such quotes will be eliminated; provided, however, that if fewer than
three Reference Dealers selected by the Calculation Agent are quoting as
mentioned herein, the CMT Rate determined as of such CMT Rate Interest
Determination Date will be the CMT Rate in effect on such CMT Rate Interest
Determination Date. If two Treasury Notes with an original maturity as described
in the second preceding sentence have remaining terms to maturity equally close
to the Designated CMT Maturity Index, the Calculation Agent will obtain
quotations for the Treasury Note with the shorter remaining term to maturity and
will use such quotations to calculate the CMT Rate as set forth above.

         "Designated CMT Telerate Page" means the display on the Dow Jones
Telerate Service (or any successor service) on the page specified on the face
hereof (or any other page as may replace such page on that service (or any
successor service) for the purpose of displaying Treasury Constant Maturities as
reported in H.15(519)). If no such page is specified on the face hereof, the
Designated CMT Telerate Page shall be 7052, for the most recent week.

         "Designated CMT Maturity Index" means the original period to maturity
of the United States Treasury securities (either one, two, three, five, seven,
10, 20 or 30 years) specified on the face hereof with respect to which the CMT
Rate will be calculated. If no such maturity is specified on the face hereof,
the Designated CMT Maturity Index shall be two years.

         Commercial Paper Rate. If an Interest Rate Basis for this Note is
specified on the face hereof as the Commercial Paper Rate, the Commercial Paper
Rate shall be determined as of the applicable Interest Determination Date (a
"Commercial Paper Rate Interest Determination Date") as the Money Market Yield
(as defined below) on such date of the rate for commercial paper having the
Index Maturity as published in H.15(519) under the heading "Commercial Paper".
In the event that such rate is not published by 3:00 P.M., New York City time,
on the related Calculation Date, then the Commercial


                                      B-13

<PAGE>   35

Paper Rate on such Commercial Paper Rate Interest Determination Date will be the
Money Market Yield of the rate for commercial paper having the Index Maturity as
published in Composite Quotations under the caption "Commercial--Nonfinancial
Paper" (with an Index Maturity of one month or three months being deemed to be
equivalent to an Index Maturity of 30 days or 90 days, respectively). If such
rate is not yet published in either H.15(519) or Composite Quotations by 3:00
P.M., New York City time, on such Calculation Date, then the Commercial Paper
Rate on such Commercial Paper Rate Interest Determination Date will be
calculated by the Calculation Agent and shall be the Money Market Yield of the
arithmetic mean of the offered rates at approximately 11:00 A.M., New York City
time, on such Commercial Paper Rate Interest Determination Date of three leading
dealers of commercial paper in The City of New York selected by the Calculation
Agent for commercial paper having the Index Maturity placed for an industrial
issuer whose bond rating is "Aa," or the equivalent, from a nationally
recognized statistical rating organization; provided, however, that if the
dealers so selected by the Calculation Agent are not quoting as mentioned in
this sentence, the Commercial Paper Rate determined as of such Commercial Paper
Rate Interest Determination Date will be the Commercial Paper Rate in effect on
such Commercial Paper Rate Interest Determination Date.

         "Money Market Yield" means a yield (expressed as a percentage)
calculated in accordance with the following formula:

         Money Market Yield =             D x 360
                                --------------------------- x 100
                                       360 - (D x M)

where "D" refers to the applicable per annum rate for commercial paper quoted on
a bank discount basis and expressed as a decimal, and "M" refers to the actual
number of days in the applicable Interest Reset Period.

         11th District Cost of Funds Rate. If an Interest Rate Basis for this
Note is specified on the face hereof as the 11th District Cost of Funds Rate,
the 11th District Cost of Funds Rate shall be determined as of the applicable
Interest Determination Date (an "11th District Cost of Funds Rate Interest
Determination Date") as the rate equal to the monthly weighted average cost of
funds for the calendar month immediately preceding the month in which such 11th
District Cost of Funds Rate Interest Determination Date falls, as set forth
under the caption "11th District" on Telerate Page 7058 as of 11:00 A.M., San
Francisco time, on such 11th District Cost of Funds Rate Interest Determination
Date. If such rate does not appear on Telerate Page 7058 on such 11th District
Cost of Funds Rate Interest Determination Date, then the 11th District Cost of
Funds Rate on such 11th District Cost of Funds Rate Interest Determination Date
shall be the monthly weighted average cost of funds paid by member institutions
of the 11th Federal Home Loan Bank District that was most recently announced
(the "Index") by the FHLB of San Francisco as such cost of funds for the
calendar month immediately preceding such 11th District Cost of Funds Rate
Interest Determination Date. If the FHLB of San Francisco fails to announce the
Index on or prior to such 11th District Cost of Funds Rate Interest
Determination Date for the calendar month immediately preceding such 11th
District Cost of Funds Rate Interest Determination Date, the 11th District Cost
of Funds Rate determined as of such 11th District Cost of Funds Rate Interest
Determination Date will be the 11th District Cost of Funds Rate in effect on
such 11th District Cost of Funds Rate Interest Determination Date.

         Federal Funds Rate. If an Interest Rate Basis for this Note is
specified on the face hereof as the Federal Funds Rate, the Federal Funds Rate
shall be determined as of the applicable Interest Determination Date (a "Federal
Funds Rate Interest Determination Date") as the rate on such date for United
States dollar federal funds as published in H.15(519) under the heading "Federal
Funds


                                      B-14

<PAGE>   36

(Effective)" or, if not published by 3:00 P.M., New York City time, on the
Calculation Date, the rate on such Federal Funds Rate Interest Determination
Date as published in Composite Quotations under the heading "Federal
Funds/Effective Rate." If such rate is not published in either H.15(519) or
Composite Quotations by 3:00 P.M., New York City time, on the related
Calculation Date, then the Federal Funds Rate on such Federal Funds Interest
Determination Date shall be calculated by the Calculation Agent and will be the
arithmetic mean of the rates for the last transaction in overnight United States
dollar federal funds arranged by three leading brokers of federal funds
transactions in The City of New York selected by the Calculation Agent, prior to
9:00 A.M., New York City time, on such Federal Funds Rate Interest Determination
Date; provided, however, that if the brokers so selected by the Calculation
Agent are not quoting as mentioned in this sentence, the Federal Funds Rate
determined as of such Federal Funds Rate Interest Determination Date will be the
Federal Funds Rate in effect on such Federal Funds Rate Interest Determination
Date.

         LIBOR. If an Interest Rate Basis for this Note is specified on the face
hereof as LIBOR, LIBOR shall be determined by the Calculation Agent as of the
applicable Interest Determination Date (a "LIBOR Interest Determination Date")
in accordance with the following provisions:

         (i) if (a) "LIBOR Reuters" is specified on the face hereof, the
arithmetic mean of the offered rates (unless the Designated LIBOR Page (as
defined below) by its terms provides only for a single rate, in which case such
single rate will be used) for deposits in the Designated LIBOR Currency having
the Index Maturity, commencing on the applicable Interest Reset Date, that
appear (or, if only a single rate is required as aforesaid, appears) on the
Designated LIBOR Page (as defined below) as of 11:00 A.M., London time, on such
LIBOR Interest Determination Date, or (b) "LIBOR Telerate" is specified on the
face hereof, or if neither "LIBOR Reuters" nor "LIBOR Telerate" is specified on
the face hereof as the method for calculating LIBOR, the rate for deposits in
the Designated LIBOR Currency having the Index Maturity, commencing on such
Interest Reset Date, that appears on the Designated LIBOR Page as of 11:00 A.M.,
London time, on such LIBOR Interest Determination Date. If fewer than two such
offered rates appear, or if no such rate appears, as applicable, LIBOR on such
LIBOR Interest Determination Date shall be determined in accordance with the
provisions described in clause (ii) below.

         (ii) with respect to a LIBOR Interest Determination Date on which fewer
than two offered rates appear, or no rate appears, as the case may be, on the
Designated LIBOR Page as specified in clause (i) above, the Calculation Agent
shall request the principal London offices of each of four major reference banks
in the London interbank market, as selected by the Calculation Agent, to provide
the Calculation Agent with its offered quotation for deposits in the Designated
LIBOR Currency for the period of the Index Maturity, commencing on the
applicable Interest Reset Date, to prime banks in the London interbank market at
approximately 11:00 A.M., London time, on such LIBOR Interest Determination Date
and in a principal amount that is representative for a single transaction in the
Designated LIBOR Currency in such market at such time. If at least two such
quotations are so provided, then LIBOR on such LIBOR Interest Determination Date
will be the arithmetic mean of such quotations. If fewer than two such
quotations are so provided, then LIBOR on such LIBOR Interest Determination Date
will be the arithmetic mean of the rates quoted at approximately 11:00 A.M., in
the applicable Principal Financial Center, on such LIBOR Interest Determination
Date by three major banks in such Principal Financial Center selected by the
Calculation Agent for loans in the Designated LIBOR Currency to leading European
banks, having the Index Maturity and in a principal amount that is
representative for a single transaction in the Designated LIBOR Currency in such
market at such time; provided, however, that if the banks so selected by the
Calculation Agent are not quoting as mentioned in this sentence, LIBOR
determined as of such LIBOR Interest Determination Date shall be LIBOR in effect
on such LIBOR Interest Determination Date.


                                      B-15

<PAGE>   37

         "Designated LIBOR Currency" means the currency or composite currency
specified on the face hereof as to which LIBOR shall be calculated. If no such
currency or composite currency is specified on the face hereof, the Designated
LIBOR Currency shall be United States dollars.

         "Designated LIBOR Page" means (a) if "LIBOR Reuters" is specified on
the face hereof, the display on the Reuter Monitor Money Rates Service (or any
successor service) on the page specified on the face hereof (or any other page
as may replace such page on such service (or any successor service)), for the
purpose of displaying the London interbank rates of major banks for the
Designated LIBOR Currency, or (b) if "LIBOR Telerate" is specified on the face
hereof or if neither "LIBOR Reuters" nor "LIBOR Telerate" is specified on the
face hereof as the method for calculating LIBOR, the display on the Dow Jones
Telerate Service (or any successor service) on the page specified on the face
hereof (or any other page as may replace such page on such service (or any
successor service)), for the purpose of displaying the London interbank rates of
major banks for the Designated LIBOR Currency.

         Kenny Rate. If an Interest Rate Basis for this Note is specified on the
face hereof as the Kenny Rate, the Kenny Rate shall be determined as of the
applicable Interest Determination Date (a "Kenny Rate Interest Determination
Date") as the rate equal to the high grade weekly index (the "Weekly Index") on
such date made available by Kenny Information Systems ("Kenny") to the
Calculation Agent. The Weekly Index is, and shall be, based upon 30 day yield
evaluations at par of bonds, the interest on which is exempt from Federal income
taxation under the Internal Revenue Code of 1986, as amended (the "Code"), of
not less than five high grade component issuers selected by Kenny which shall
include, without limitation, issuers of general obligation bonds. The specific
issuers included among the component issuers may be changed from time to time by
Kenny in its discretion. The bonds on which the Weekly Index is based shall not
include any bonds on which the interest is subject to a minimum tax or similar
tax under the Code, unless all tax-exempt bonds are subject to such tax. In the
event Kenny ceases to make available such Weekly Index, a successor indexing
agent will be selected by the Calculation Agent, such index to reflect the
prevailing rate for bonds rated in the highest short-term rating category by
Moody's Investors Service, Inc. and Standard & Poor's Corporation in respect of
issuers most closely resembling the high grade component issuers selected by
Kenny for its Weekly Index, the interest on which is (A) variable on a weekly
basis, (B) exempt from Federal income taxation under the Code, and (C) not
subject to a minimum tax or similar tax under the Code, unless all tax-exempt
bonds are subject to such tax. If such successor indexing agent is not
available, the rate for any Kenny Rate Interest Determination Date shall be 67%
of the rate determined if the Treasury Rate option had been originally selected.

         Prime Rate. If an Interest Rate Basis for this Note is specified on the
face hereto as the Prime Rate, the Prime Rate shall be determined as of the
applicable Interest Determination Date (a "Prime Rate Interest Determination
Date") as the rate on such date as such rate is published in H.15(519) under the
heading "Bank Prime Loan." If such rate is not published prior to 3:00 P.M., New
York City time, on the related Calculation Date, then the Prime Rate shall be
the arithmetic mean of the rates of interest publicly announced by each bank
that appears on the Reuters Screen USPRIME1 Page (as defined below) as such
bank's prime rate or base lending rates as in effect for such Prime Rate
Interest Determination Date. If fewer than four such rates appear on the Reuters
Screen USPRIME1 Page for such Prime Rate Interest Determination Date, then the
Prime Rate shall be the arithmetic mean of the prime rates quoted on the basis
of the actual number of days in the year divided by a 360-day year as of the
close of business on such Prime Rate Interest Determination Date by four major
money center banks in The City of New York selected by the Calculation Agent. If
fewer than four such quotations are so provided, the Prime Rate shall be the
arithmetic mean of four prime rates quoted on the basis of the actual number of
days in the year divided by a 360-day year as of the close of business on such
Prime Rate Interest Determination Date as furnished in The City of New York by
the major money center banks, if any, that


                                      B-16

<PAGE>   38

have provided such quotations and by a reasonable number of substitute banks or
trust companies to obtain four such prime rate quotations, provided such
substitute banks or trust companies are organized and doing business under the
laws of the United States, or any State thereof, each having total equity
capital of at least U.S. $500 million and being subject to supervision or
examination by Federal or State authority, selected by the Calculation Agent to
provide such rate or rates; provided, however, that if the banks or trust
companies so selected by the Calculation Agent are not quoting as mentioned in
this sentence, the Prime Rate determined as of such Prime Rate Interest
Determination Date will be the Prime Rate in effect on such Prime Rate Interest
Determination Date.

         "Reuters Screen USPRIME1 Page" means the display designated as page
"USPRIME1" on the Reuter Monitor Money Rates Service (or any successor service)
(or such other page as may replace the USPRIME1 page on such service (or any
successor service) for the purpose of displaying prime rates or base lending
rates of major United States banks).

         Treasury Rate. If an Interest Rate Basis for this Note is specified on
the face hereof as the Treasury Rate, the Treasury Rate shall be determined as
of the applicable Interest Determination Date (a "Treasury Rate Interest
Determination Date") as the rate from the auction held on such Treasury Rate
Interest Determination Date (the "Auction") of direct obligations of the United
States ("Treasury Bills") having the Index Maturity, as such rate is published
in H.15(519) under the heading "Treasury bills-auction average (investment)" or,
if not published by 3:00 P.M., New York City time, on the related Calculation
Date, the auction average rate of such Treasury Bills (expressed as a bond
equivalent on the basis of a year of 365 or 366 days, as applicable, and applied
on a daily basis) as otherwise announced by the United States Department of the
Treasury. In the event that the results of the Auction of Treasury Bills having
the Index Maturity are not reported as provided above by 3:00 P.M., New York
City time, on such Calculation Date, or if no such Auction is held, then the
Treasury Rate shall be calculated by the Calculation Agent and shall be a yield
to maturity (expressed as a bond equivalent on the basis of a year of 365 or 366
days, as applicable, and applied on a daily basis) of the arithmetic mean of the
secondary market bid rates, as of approximately 3:30 P.M., New York City time,
on such Treasury Rate Interest Determination Date, of three leading primary
United States government securities dealers selected by the Calculation Agent,
for the issue of Treasury Bills with a remaining maturity closest to the Index
Maturity; provided, however, that if the dealers so selected by the Calculation
Agent are not quoting as mentioned in this sentence, the Treasury Rate
determined as of such Treasury Rate Interest Determination Date will be the
Treasury Rate in effect on such Treasury Rate Interest Determination Date.

         Notwithstanding the foregoing, the interest rate hereon shall not be
greater than the Maximum Interest Rate, if any, or less than the Minimum
Interest Rate, if any, in each case as specified on the face hereof. The
interest rate on this Note will in no event be higher than the maximum rate
permitted by New York law, as the same may be modified by United States law of
general application.

         The Calculation Agent shall calculate the interest rate hereon on or
before each Calculation Date. The "Calculation Date", if applicable, pertaining
to any Interest Determination Date shall be the earlier of (i) the tenth
calendar day after such Interest Determination Date or, if such day is not a
Business Day, the next succeeding Business Day or (ii) the Business Day
immediately preceding the applicable Interest Payment Date or the Maturity Date,
as the case may be. At the request of the holder hereof, the Calculation Agent
will provide to the holder hereof the interest rate hereon then in effect and,
if determined, the interest rate that will become effective as a result of a
determination made for the next succeeding Interest Reset Date.

         Accrued interest hereon shall be an amount calculated by multiplying
the principal amount hereof by an accrued interest factor. Such accrued interest
factor shall be computed by adding the interest factor


                                      B-17

<PAGE>   39

calculated for each day in the applicable Interest Period. Unless otherwise
specified as the Day Count Convention on the face hereof, the interest factor
for each such date shall be computed by dividing the interest rate applicable to
such day by 360 if the CD Rate, the Commercial Paper Rate, the 11th District
Cost of Funds Rate, the Federal Funds Rate, LIBOR or the Prime Rate is an
applicable Interest Rate Basis or by the actual number of days in the year if
the CMT Rate or the Treasury Rate is an applicable Interest Rate Basis, or by
365 if Kenny Rate is an applicable Interest Rate Basis. Unless otherwise
specified as the Day Count Convention on the face hereof, the interest factor
for this Note, if the interest rate is calculated with reference to two or more
Interest Rate Bases, shall be calculated in each period in the same manner as if
only the Applicable Interest Rate Basis specified on the face hereof applied.

         All percentages resulting from any calculation on this Note shall be
rounded to the nearest one hundred-thousandth of a percentage point, with five
one-millionths of a percentage point rounded upwards, and all amounts used in or
resulting from such calculation on this Note shall be rounded, in the case of
United States dollars, to the nearest cent or, in the case of a Specified
Currency other than United States dollars, to the nearest unit (with one-half
cent or unit being rounded upwards).

         If an Event of Default, as defined in the Indenture, shall occur and be
continuing, the principal of and premium (if any) and interest on the Notes
either shall automatically become or may be declared due and payable in the
manner and with the effect provided in the Indenture.

         The Indenture contains provisions for defeasance at any time of (a) the
entire indebtedness of the Company on this Note and (b) certain restrictive
covenants and the related defaults and Events of Default applicable to the
Company, in each case, upon compliance by the Company with certain conditions
set forth in the Indenture, which provisions apply to this Note.

         As provided in and subject to the provisions of the Indenture, the
holder of this Note shall not have the right to institute any proceeding with
respect to the Indenture or for the appointment of a receiver or trustee or for
any other remedy hereunder, unless (i) such holder shall have previously given
written notice to the Trustee of a continuing Event of Default with respect to
the Securities of this series, (ii) the holders of not less than 25% in
principal amount of the Securities of this series at the time Outstanding shall
have made written request to the Trustee to institute proceedings in respect of
such Event of Default in its own name as Trustee, (iii) such holder or holders
have offered reasonable indemnity satisfactory to the Trustee against the costs,
expenses and liabilities to be incurred in compliance with such request, (iv)
the Trustee shall have failed to institute any such proceeding for 60 days after
its receipt of such notice, request and offer of indemnity, and (v) the Trustee
shall not have received, during the 60-day period referenced in clause (iv)
above, from the holders of a majority in principal amount of Securities of this
series at the time Outstanding in a direction inconsistent with such request;
provided that, no one or more holder shall have any right in any manner whatever
by virtue of, or by availing of, any provision of the Indenture to affect,
disturb or prejudice the rights of any other holder, or to obtain or to seek to
obtain priority or preference over any other holder or to enforce any right
under the Indenture, except in the manner therein provided and for the equal and
ratable benefit of all holders. The foregoing shall not apply to any suit
instituted by the holder of this Note for the enforcement of any payment of
principal hereof (and premium or Make-Whole Amount, if any) or any interest
thereon on or after the respective due dates expressed herein.

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the holders of the Securities at any time by the
Company and the Trustee with the consent of the holders of not less than a
majority of the aggregate principal amount of all Securities at the time
outstanding and affected thereby. The Indenture also contains provisions
permitting the holders of not less than a majority of the aggregate


                                      B-18

<PAGE>   40

principal amount of the outstanding Securities of any series, on behalf of the
holders of all such Securities, to waive compliance by the Company with certain
provisions of the Indenture. Furthermore, provisions in the Indenture permit the
holders of not less than a majority of the aggregate principal amount of the
outstanding Securities of any series, in certain instances, to waive, on behalf
of all of the holders of Securities of such series, certain past defaults under
the Indenture and their consequences. Any such consent or waiver by the holder
of this Note shall be conclusive and binding upon such holder and upon all
future holders of this Note and other Notes issued upon the registration of
transfer hereof or in exchange hereof or in lieu hereof, whether or not notation
of such consent or waiver is made upon this Note.

         No reference herein to the Indenture and no provision of this Note or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay principal, premium, if any, and interest in
respect of this Note at the times, places and rate or formula, and in the coin
or currency, herein prescribed.

         As provided in the Indenture and subject to certain limitations therein
and herein set forth, the transfer of this Note is registrable in the Security
Register of the Company upon surrender of this Note for registration of transfer
at the office or agency of the Company in any place where the principal hereof
and any premium or interest hereon are payable, duly endorsed by, or accompanied
by a written instrument of transfer in form satisfactory to the Company and the
Security Registrar duly executed by, the holder hereof or by his attorney duly
authorized in writing, and thereupon one or more new Notes, of authorized
denominations and for the same aggregate principal amount, will be issued to the
designated transferee or transferees.

         As provided in the Indenture and subject to certain limitations therein
and herein set forth, this Note is exchangeable for a like aggregate principal
amount of Notes of different authorized denominations but otherwise having the
same terms and conditions, as requested by the holder hereof surrendering the
same.

         No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Note for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
holder in whose name this Note is registered as the owner thereof for all
purposes, whether or not this Note be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

         No recourse under or upon any obligation, covenant or agreement
contained in the Indenture or in this Note, or because of any indebtedness
evidenced thereby or hereby, (including without limitation, any obligation or
indebtedness relating to the principal of, or premium or Make-Whole Amount, if
any, interest or any other amounts due, or claimed to be due, on this Security),
or for any claim based thereon or otherwise in respect thereof, shall be had (i)
against Liberty Property Trust or any other partner of the Company, (ii) against
any person which owns an interest, directly or indirectly, in any partner in the
Company, or (iii) against any promoter, as such or, against any past, present or
future stockholder, partner, officer or director, as such, of the Company or of
any successor, either directly or through the Company or any successor, under
any rule of law, statue 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 of this Note by
the holder thereof and as part of the consideration for the issue of the
Securities of this series. The holder of this Security acknowledges


                                      B-19

<PAGE>   41

by acceptance of this Security that its sole remedies under the Indenture for
any Default by the Company in the payment of principal of, or any premium or
Make-Whole Amount, if any, interest or any amounts due, or claimed to be due, on
this Security, or otherwise, are limited to claims against the property of the
Company as provided in Sections 111 and 503 of the Indenture.

         THE INDENTURE AND THE SECURITIES, INCLUDING THIS NOTE, SHALL BE
GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

         Pursuant to a recommendation promulgated by the Committee on Uniform
Security Identification Procedures, the Company has caused "CUSIP" numbers to be
printed on the Securities of this series as a convenience to the holders of such
Securities. No representation is made as to the correctness or accuracy of such
CUSIP numbers as printed on the Securities, and reliance may be placed only on
the other identification numbers printed hereon.


                                      B-20

<PAGE>   42

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this Note, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COMM  -  as tenants in common              UNIF GIFT MIN ACT -
TEN ENT   -  as tenants by the entities        ______ Custodian ______
JT TEN    -  as joint tenants with right of    (Cust)           (Minor)
             survivorship and not as tenants   Under Uniform Gifts to Minors
             in common                         Act_____________________
                                                         (State)

Additional abbreviations may also be used though not in the above list.

                           ----------------------------
                                   ASSIGNMENT

--------------------------------------------------------------------------------
     Please insert social security or other identifying number of assignee.

              FOR VALUE RECEIVED, the undersigned hereby sell(s),
                         assign(s) and transfer(s) unto

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

--------------------------------------------------------------------------------
             (Please print or typewrite name and address including
                          postal zip code of assignee)

the within Note and all rights thereunder hereby irrevocably constituting and
appointing __________________________, attorney to transfer said Note on the
books of the Trustee, with full power of substitution in the premises.

Dated:_________________, 199__
          

         -----------------------------------------------------
         Notice: The signature(s) on this Assignment must correspond with the
         name(s) as written upon the face of this Note in every particular,
         without alteration or enlargement or any change whatsoever.

         Signature must be guaranteed by an "eligible guarantor institution,"
         that is, a bank, stockbroker, savings and loan association or credit
         union meeting the requirements of the Registrar, which requirements
         include membership or participation in the Securities Transfer Agents
         Medallion Program ("STAMP") or such other "signature guarantee program"
         as may be determined by the Registrar in addition to, or in
         substitution for, STAMP, all in accordance with the Securities Exchange
         Act of 1934, as amended.



                                      B-21

<PAGE>   43

                            OPTION TO ELECT REPAYMENT

         The undersigned hereby irrevocably request(s) and instruct(s) the
Company to repay this Note (or portion hereof specified below) pursuant to its
terms at a price equal to 100% of the principal amount to be repaid, together
with unpaid interest accrued hereon to the Repayment Date, to the undersigned,
at_____________________________________________________________________________
         (Please print or typewrite name and address of the undersigned)

         For this Note to be repaid, the Trustee must receive at its corporate
trust office in the Borough of Manhattan, The City of New York, not more than 60
nor less than 30 calendar days prior to the Repayment Date, this Note with this
"Option to Elect Repayment" form duly completed.

         If less than the entire principal amount of this Note is to be repaid,
specify the portion hereof (which shall be increments of U.S. $1,000 (or, if the
Specified Currency is other than United States dollars, the minimum Authorized
Denomination specified on the face hereof)) which the holder elects to have
repaid and specify the denomination or denominations (which shall be an
Authorized Denomination) of the Notes to be issued to the holder for the portion
of this Note not being repaid (in the absence of any such specification, one
such Note will be issued for the portion not being repaid).

Principal Amount to be Repaid:  $

Date:

                           ----------------------------------------
                           Notice: The signature(s) on this Option to Elect
                           Repayment must correspond with the name(s) as written
                           upon the face of this Note in every particular,
                           without alteration or enlargement or any change
                           whatsoever.


                                      B-22