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                                                                    Exhibit 4.17

                                NTL INCORPORATED

                                  $600,000,000

                   7% CONVERTIBLE SUBORDINATED NOTES DUE 2008

                                    INDENTURE

                          Dated as of December 16, 1998


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

                            The Chase Manhattan Bank

                                     Trustee

                            ------------------------
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                                TABLE OF CONTENTS

ARTICLE I                                                                    1
   Section 1.01. Definitions.                                                1
   Section 1.02. Other Definitions.                                          8
   Section 1.03. Incorporation by Reference of Trust Indenture
                 Act.                                                        9
   Section 1.04. Rules of Construction.                                      9
ARTICLE II. THE NOTES.                                                       9
   Section 2.01. Form and Dating.                                            9
   Section 2.02. Execution and Authentication.                              11
   Section 2.03. Registrar and Paying Agent.                                12
   Section 2.04. Paying Agent to Hold Money in Trust.                       12
   Section 2.05. Holder Lists.                                              12
   Section 2.06. Transfer and Exchange.                                     12
   Section 2.07. Replacement Notes.                                         17
   Section 2.08. Outstanding Notes.                                         17
   Section 2.09. Treasury Notes.                                            18
   Section 2.10. Temporary Notes; Global Notes.                             18
   Section 2.11. Cancellation.                                              19
   Section 2.12. Defaulted Interest.                                        19
ARTICLE III. REDEMPTION.                                                    19
   Section 3.01. Notices to Trustee.                                        19
   Section 3.02. Selection of Notes to Be Redeemed.                         19
   Section 3.03. Notice of Redemption.                                      20
   Section 3.04. Effect of Notice of Redemption.                            20
   Section 3.05. Deposit of Redemption Price.                               21
   Section 3.06. Notes Redeemed in Part.                                    21
   Section 3.07. Optional Redemption and Optional Tax Redemption.           21
   Section 3.08. Mandatory Redemption.                                      21
   Section 3.09. Purchase Offer.                                            21
ARTICLE IV. COVENANTS.                                                      23
   Section 4.01. Payment of Notes.                                          23
   Section 4.02. Reports.                                                   23
   Section 4.03. Compliance Certificate.                                    24
   Section 4.04. Stay, Extension and Usury Laws.                            24
   Section 4.05. Corporate Existence.                                       24
   Section 4.06. Taxes.                                                     25
   Section 4.07. Change of Control.                                         25
   Section 4.08. Payment of Additional Amounts.                             25
ARTICLE V. CONVERSION.                                                      26
   Section 5.01. Conversion Privilege.                                      26
   Section 5.02. Conversion Procedure.                                      26
   Section 5.03. Fractional Shares.                                         27
   Section 5.04. Taxes on Conversion.                                       27
   Section 5.05. Company to Provide Stock.                                  27
   Section 5.06. Adjustment of Conversion Price.                            27
   Section 5.07. No Adjustment.                                             30
   Section 5.08. Other Adjustments.                                         30
   Section 5.09. Adjustments for Tax Purposes.                              31
   Section 5.10. Notice of Adjustment.                                      31
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   Section 5.11. Notice of Certain Transactions.                            31
   Section 5.12. Effect of Reclassifications, Consolidations,
                 Mergers or Sales on Conversion Privilege.                  32
   Section 5.13. Trustee's Disclaimer.                                      32
ARTICLE VI. SUBORDINATION.                                                  33
   Section 6.01. Agreement to Subordinate and Ranking.                      33
   Section 6.02. No Payment on Notes if Senior Debt in Default.             33
   Section 6.03. Distribution on Acceleration of Notes;
                 Dissolution and Reorganization; Subrogation of Notes.      34
   Section 6.04. Reliance by Senior Debt on Subordination 
                 Provisions.                                                37
   Section 6.05. No Waiver of Subordination Provisions.                     37
   Section 6.06. Trustee's Relation to Senior Debt.                         37
   Section 6.07. Other Provisions Subject Hereto.                           38
ARTICLE VII. SUCCESSORS.                                                    38
   Section 7.01. Merger, Consolidation or Sale of Assets.                   38
   Section 7.02. Successor Corporation Substituted.                         39
ARTICLE VIII. DEFAULTS AND REMEDIES.                                        39
   Section 8.01. Events of Default.                                         39
   Section 8.02. Acceleration.                                              41
   Section 8.03. Other Remedies.                                            42
   Section 8.04. Waiver of Past Defaults.                                   42
   Section 8.05. Control by majority.                                       42
   Section 8.06. Limitation on Suits.                                       42
   Section 8.07. Rights of Holders to Receive Payment.                      43
   Section 8.08. Collection Suit by Trustee.                                43
   Section 8.09. Trustee May File Proofs of Claim.                          43
   Section 8.10. Priorities.                                                43
   Section 8.11. Undertaking for Costs.                                     43
ARTICLE IX. TRUSTEE.                                                        44
   Section 9.01. Duties of Trustee.                                         44
   Section 9.02. Rights of Trustee.                                         44
   Section 9.03. Individual Rights of Trustee.                              45
   Section 9.04. Trustee's Disclaimer.                                      45
   Section 9.05. Notice of Defaults.                                        45
   Section 9.06. Reports by Trustee to Holders.                             45
   Section 9.07. Compensation and Indemnity.                                46
   Section 9.08. Replacement of Trustee.                                    46
   Section 9.09. Successor Trustee by Merger, Etc.                          47
   Section 9.10. Eligibility; Disqualification.                             47
   Section 9.11. Preferential Collection of Claims Against
                 Company.                                                   47
ARTICLE X. DISCHARGE OF INDENTURE                                           48
   Section 10.01. Termination of Company's Obligations.                     48
   Section 10.02. Repayment to Company.                                     48
ARTICLE XI. AMENDMENTS, SUPPLEMENTS AND WAIVERS.                            48
   Section 11.01. Without Consent of Holders.                               48
   Section 11.02. With Consent of Holders.                                  48
   Section 11.03. Compliance with Trust Indenture Act.                      49
   Section 11.04. Revocation and Effect of Consents.                        49
   Section 11.05. Notation on or Exchange of Notes.                         50
   Section 11.06. Trustee Protected.                                        50
ARTICLE XII. MISCELLANEOUS.                                                 50


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   Section 12.01. Trust Indenture Act Controls.                             50
   Section 12.02. Notices.                                                  50
   Section 12.03. Communication by Holders with Other Holders.              51
   Section 12.04. Certificate and Opinion as to Conditions
                  Precedent.                                                51
   Section 12.05. Statements Required in Certificate or Opinion.            51
   Section 12.06. Rules by Trustee and Agents.                              52
   Section 12.07. Legal Holidays.                                           52
   Section 12.08. No Recourse Against Others.                               52
   Section 12.09. Counterparts and Facsimile Signatures.                    52
   Section 12.10. Variable Provisions.                                      52
   Section 12.11. Governing Law.                                            53
   Section 12.12. No Adverse Interpretation of Other Agreements.            53
   Section 12.13. Successors.                                               53
   Section 12.14. Severability.                                             53
   Section 12.15. Table of Contents, Headings, Etc.                         53


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                             CROSS-REFERENCE TABLE*
Trust Indenture Act Section                                    Indenture Section

310 (a)(1)                                                              9.10
(a)(2)                                                                  9.10
(a)(3)                                                                  N.A.
(a)(4)                                                                  N.A.
(a)(5)                                                                  9.10
(b)                                                                     9.08,
                                                                        9.10
(c)                                                                     N.A.
311(a)                                                                  9.11
(b)                                                                     9.11
(c)                                                                     N.A.
312 (a)                                                                 2.05
(b)                                                                     12.03
(c)                                                                     12.03
313(a)                                                                  9.06
(b)(1)                                                                  N.A.
(b)(2)                                                                  9.06
(c)                                                                     9.06
(d)                                                                     9.06
314(a)                                                                  4.02
                                                                        4.03,
                                                                        12.02
(b)                                                                     N.A.
(c)(1)                                                                  12.04
(c)(2)                                                                  12.04
(c)(3)                                                                  N.A.
(d)                                                                     N.A.
(e)                                                                     N.A.
(f)                                                                     N.A.
315(a)                                                                  9.01(b)
(b)                                                                     9.05
(c)                                                                     9.01(a)


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(d)                                                                     9.01(c)
(e)                                                                     8.11
316 (a)(last sentence)                                                  2.09
(a)(1)(A)                                                               8.05
(a)(1)(B)                                                               8.04
(a)(2)                                                                  N.A.
(b)                                                                     8.07
(c)                                                                     11.04
317 (a)(1)                                                              8.08
(a)(2)                                                                  8.09
(b)                                                                     2.04
318 (a)                                                                 N.A.

N.A. means not applicable.
*     This Cross-Reference Table is not part of the Indenture.


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      INDENTURE, dated as of December 16, 1998, between NTL Incorporated, a
Delaware corporation (the "Company"), and The Chase Manhattan Bank, a New York
corporation, as trustee (the "Trustee").

      Each party agrees as follows for the benefit of the other party and for
the equal and ratable benefit of the Holders (as defined in Section 1.01 hereof)
of the Company's 7% Convertible Subordinated Notes due 2008 (the "Notes"):

                                   ARTICLE I.

Section 1.01. Definitions.

      "Affiliate" of any specified Person means any other Person directly
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For purposes of this definition, "control"
(including, with correlative meanings, the terms "controlling," "controlled by"
and "under common control with"), as used with respect to any Person, shall mean
the possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of such Person, whether through the
ownership of voting securities, by agreement or otherwise; provided, however,
that beneficial ownership of 10% or more of the voting securities of a Person
shall be deemed to be control.

      "Agent" means any Registrar, Paying Agent or Conversion Agent.

      "Annualized Pro Forma EBITDA" means, with respect to any Person, such
Person's Pro Forma EBITDA for the latest fiscal quarter multiplied by four.

      "Asset Sale" means (i) any sale, lease, transfer, conveyance or other
disposition of any assets (including by way of a sale-and-leaseback) other than
the sale or transfer of inventory or goods held for sale in the ordinary course
of business or (ii) any issuance, sale, lease, transfer, conveyance or other
disposition of any Equity Interests of any of the Company's Restricted
Subsidiaries to any Person; in either case other than (A) to (w) the Company,
(x) any Wholly Owned Subsidiary, or (y) any Subsidiary which is a Subsidiary of
the Company on the Issuance Date provided that at the time of and after giving
effect to such issuance, sale, lease, transfer, conveyance or other disposition
to such Subsidiary, the Company's ownership percentage in such Subsidiary is
equal to or greater than such percentage on the Issuance Date or (B) the
issuance, sale, transfer, conveyance or other disposition of Equity Interests of
a Subsidiary in exchange for capital contributions made on a pro rata basis by
the holders of the Equity Interests of such Subsidiary.

      "Board of Directors" means the Board of Directors of the Company or any
authorized committee of the Board of Directors.

      "Board Resolution" means a duly authorized resolution of the Board of
Directors.

      "Business Day" means any day that is not a Legal Holiday.

      "Capital Stock" means any and all shares, interests, participations,
rights or other equivalents (however designated) of corporate stock, including,
without limitation, partnership interests.

      "Change of Control" means (i) the sale, lease or transfer of all or
substantially all of the assets of


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the Company to any "Person" or "group" (within the meaning of Sections 13(d)(3)
and 14(d)(2) of the Exchange Act or any successor provision to either of the
foregoing, including any group acting for the purpose of acquiring, holding or
disposing of securities within the meaning of Rule 13d-5(b)(1) under the
Exchange Act) (other than any Permitted Holder), (ii) the approval by the
requisite stockholders of the Company of a plan of liquidation or dissolution of
the Company, (iii) any "Person" or "group" (within the meaning of Sections 13(d)
and 14(d)(2) of the Exchange Act or any successor provision to either of the
foregoing, including any group acting for the purpose of acquiring, holding or
disposing of securities within the meaning of Rule 13d- 5(b)(1) under the
Exchange Act), other than any Permitted Holder, becomes the "beneficial owner"
(as defined in Rule 13d-3 under the Exchange Act) of more than 50% of the total
voting power of all classes of the voting stock of the Company and/or warrants
or options to acquire such voting stock, calculated on a fully diluted basis,
unless, as a result of such transaction, the ultimate direct or indirect
ownership of the Company is substantially the same immediately after such
transaction as it was immediately prior to such transaction, or (iv) during any
period of two consecutive years, individuals who at the beginning of such period
constituted the Company's Board of Directors (together with any new directors
whose election or appointment by such board or whose nomination for election by
the shareholders of the Company was approved by a vote of a majority of the
directors then still in office who were either directors at the beginning of
such period or whose election or nomination for election was previously so
approved) cease for any reason to constitute a majority of the Company's Board
of Directors then in office.

      "Common Stock" means the common stock, par value $0.01 per share, of the
Company as the same exists at the date of the execution of this Indenture or as
such stock may be constituted from time to time.

      "Company" means the party named as such above until a successor replaces
it in accordance with Article VII and thereafter means the successor.

      "Consolidated Interest Expense" means, for any Person, for any period, the
amount of interest in respect of Indebtedness (including amortization of
original issue discount, amortization of debt issuance costs, and non-cash
interest payments on any Indebtedness and the interest portion of any deferred
payment obligation and after taking into account the effect of elections made
under any Interest Rate Agreement, however denominated, with respect to such
Indebtedness), the amount of Redeemable Dividends, Restricted Subsidiary
Preferred Stock Dividends and the interest component of rentals in respect of
any capital lease obligation paid, in each case whether accrued or scheduled to
be paid or accrued by such Person and its Subsidiaries (other than
Non-Restricted Subsidiaries) during such period to the extent such amounts were
deducted in computing Consolidated Net Income, determined on a consolidated
basis in accordance with GAAP. For purposes of this definition, interest on a
capital lease obligation shall be deemed to accrue at an interest rate
reasonably determined by such Person to be the rate of interest implicit in such
capital lease obligation in accordance with GAAP consistently applied.

      "Consolidated Net Income" means, with respect to any Person, for any
period, the aggregate of the Net Income of such Person and its Subsidiaries
(other than Non-Restricted Subsidiaries) for such period, on a consolidated
basis, determined in accordance with GAAP; provided that (i) the Net Income of
any Person that is not a Subsidiary or that is accounted for by the equity
method of accounting shall be included only to the extent of the amount of
dividends or distributions paid to the referent Person or a Wholly Owned
Subsidiary, (ii) the Net Income of any Person that is a Subsidiary (other than a
Subsidiary of which at least 80% of the Capital Stock having ordinary voting
power for the election of directors or other governing body of such Subsidiary
is owned by the referent Person directly or indirectly through


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<PAGE>   9

one or more Subsidiaries) shall be included only to the extent of the amount of
dividends or distributions paid to the referent Person or a Wholly Owned
Subsidiary, (iii) the Net Income of any Person acquired in a pooling of
interests transaction for any period prior to the date of such acquisition shall
be excluded and (iv) the cumulative effect of a change in accounting principles
shall be excluded.

      "Daily Market Price" means the price of a share of Common Stock on the
relevant date, determined (a) on the basis of the last reported sale price
regular way of the Common Stock as reported on the Nasdaq Stock Market's
National Market (the "NNM"), or if the Common Stock is not then listed on the
NNM, as reported on such national securities exchange upon which the Common
Stock is listed, or (b) if there is no such reported sale on the day in
question, on the basis of the average of the closing bid and asked quotations
regular way as so reported, or (c) if the Common Stock is not listed on the NNM
or on any national securities exchange, on the basis of the average of the high
bid and low asked quotations regular way on the day in question in the
over-the-counter market as reported by the National Association of Securities
Dealers Automated Quotation System, or if not so quoted, as reported by National
Quotation Bureau, Incorporated, or a similar organization.

      "Default" means any event that is, or with the passage of time or the
giving of notice or both would be, an Event of Default.

      "Depositary" shall mean The Depository Trust Company, its nominees and
their respective successors.

      "Disqualified Stock" means any Capital Stock which, by its terms (or by
the terms of any security into which it is convertible or for which it is
exchangeable), or upon the happening of any event, matures or is mandatorily
redeemable, pursuant to a sinking fund obligation or otherwise, or redeemable at
the option of the holder thereof, in whole or in part, on or prior to the date
on which the Notes mature.

      "EBITDA" means, for any Person, for any period, an amount equal to (A) the
sum of (i) Consolidated Net Income for such period (exclusive of any gain or
loss realized in such period upon an Asset Sale), plus (ii) the provision for
taxes for such period based on income or profits to the extent such income or
profits were included in computing Consolidated Net Income and any provision for
taxes utilized in computing net loss under clause (i) hereof, plus (iii)
Consolidated Interest Expense for such period, plus (iv) depreciation for such
period on a consolidated basis, plus (v) amortization of intangibles for such
period on a consolidated basis, plus (vi) any other non-cash item reducing
Consolidated Net Income for such period, minus (B) all non-cash items increasing
Consolidated Net Income for such period, all for such Person and its
Subsidiaries determined in accordance with GAAP consistently applied.

      "Equity Interests" means Capital Stock and all warrants, options or other
rights to acquire Capital Stock (but excluding any Indebtedness that is
convertible into, or exchangeable for Capital Stock).

      "Excess Payment" means the excess of (A) the aggregate of the cash and
value of other consideration paid by the Company or any of its Subsidiaries with
respect to shares acquired in a tender offer or other negotiated transaction
over (B) the market value of each such acquired shares after giving effect to
the completion of a tender offer or other negotiated transaction.

      "Exchange Act" means the Securities Exchange Act of 1934, as amended.


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      "Exchange Rate Contract" means, with respect to any Person, any currency
swap agreements, forward exchange rate agreements, foreign currency futures or
options, exchange rate collar agreements, exchange rate insurance and other
agreements or arrangements, or combination thereof, the principal purpose of
which is to provide protection against fluctuations in currency exchange rates.
An Exchange Rate Contract may also include an Interest Rate Agreement.

      "Existing Convertible Notes" means the Company's 7% Convertible
Subordinated Notes due 2008 issued pursuant to an indenture dated as of June 12,
1996, between the Company and The Chase Manhattan Bank (formerly known as
Chemical Bank), as trustee.

      "GAAP" means generally accepted accounting principles set forth in the
opinions and pronouncements of the Accounting Principles Board of the American
Institute of Certified Public Accountants and statements and pronouncements of
the Financial Accounting Standards Board or in such other statements by such
other entity as approved by a significant segment of the accounting profession,
which are in effect on the Issuance Date.

      "Guarantee" means a guarantee (other than by endorsement of negotiable
instruments for collection in the ordinary course of business), direct or
indirect, in any manner (including, without limitation, letters of credit and
reimbursement agreements in respect thereof), of all or any part of any
Indebtedness.

      "Holder" means a Person in whose name a Note is registered in the register
referred to in Section 2.03.

      "Indebtedness" means, with respect to any Person, any indebtedness of such
Person, whether or not contingent, in respect of borrowed money or evidenced by
bonds, notes, debentures or similar instruments or letters of credit (or
reimbursement agreements in respect thereof) or representing the balance
deferred and unpaid of the purchase price of any property (including pursuant to
capital leases and sale-and-leaseback transactions) or representing any hedging
obligations under an Exchange Rate Contract or an Interest Rate Agreement,
except any such balance that constitutes an accrued expense or trade payable, if
and to the extent any of the foregoing indebtedness (other than obligations
under an Exchange Rate Contract or an Interest Rate Agreement) would appear as a
liability upon a balance sheet of such Person prepared in accordance with GAAP,
and also includes, to the extent not otherwise included, the Guarantee of items
which would be included within this definition.

      "Indenture" means this Indenture, as amended from time to time.

      "Initial Purchasers" means Donaldson, Lufkin & Jenrette Securities
Corporation, Morgan Stanley & Co. Incorporated, Goldman, Sachs & Co., Chase
Securities Inc., Salomon Smith Barney Inc., BT Alex. Brown Incorporated and
Warburg Dillon Read LLC.

      "Interest Rate Agreement" means, for any Person, any interest rate swap
agreement, interest rate cap agreement, interest rate collar agreement, or other
similar agreement designed to protect the party indicated therein against
fluctuations in interest rates.

      "Issuance Date" means the date on which the Notes are first authenticated
and issued.

      "License" means any license issued or awarded pursuant to the Broadcasting
Act 1990, the Cable and Broadcasting Act 1984, the Telecommunications Act 1984
or the Wireless Telegraphy Act 1948 (in


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each case, as such Acts may, from time to time, be amended, modified or
re-enacted) (or equivalent statutes of any jurisdiction) to operate or own a
Cable Business.

      "Liquidated Damages" has the meaning set forth in Section 2 of the Notes.

      "Material License" means a License held by the Company or any of its
Subsidiaries which License at the time of determination covers a number of Net
Households which equals or exceeds 5% of the aggregate number of Net Households
covered by all of the Licenses held by the Company and its Subsidiaries at such
time.

      "Material Subsidiary" means (i) NTL UK Group, Inc. (formerly known as OCOM
Sub II, Inc.), NTL Group Limited, CableTel Surrey, CableTel Cardiff Limited,
CableTel Glasgow, CableTel Newport and CableTel Kirklees and (ii) any other
Subsidiary of the Company which is a "significant subsidiary" as defined in Rule
1-02(w) of Regulation S-X under the Securities Act and the Exchange Act (as such
Regulation is in effect on the date hereof).

      "Net Households" means the product of (i) the number of households covered
by a License in the United Kingdom and (ii) the percentage of the entity holding
such License which is owned directly or indirectly by the Company.

      "Net Income" means, with respect to any Person for a specific period, the
net income (loss) of such Person during such period, determined in accordance
with GAAP, excluding, however, any gain (but not loss) during such period,
together with any related provision for taxes on such gain (but not loss),
realized during such period in connection with any Asset Sale (including,
without limitation, dispositions pursuant to sale-and-leaseback transactions),
and excluding any extraordinary gain (but not loss) during such period, together
with any related provision for taxes on such extraordinary gain (but not loss).

      "Non-Recourse Debt" means Indebtedness or that portion of Indebtedness as
to which none of the Company, nor any Restricted Subsidiary: (i) provides credit
support (including any undertaking, agreement or instrument which would
constitute Indebtedness); (ii) is directly or indirectly liable; or (iii)
constitutes the lender.

      "Non-Restricted Subsidiary" means (A) a Subsidiary that (a) at the time of
its designation by the Board of Directors as a Non-Restricted Subsidiary has not
acquired any assets, at any previous time, directly or indirectly from the
Company or any of its Restricted Subsidiaries, (b) has no Indebtedness other
than Non-Recourse Debt and (c) that at the time of such designation, after
giving pro forma effect to such designation, the ratio of Indebtedness to
Annualized Pro Forma EBITDA of the Company is equal to or less than the ratio of
Indebtedness to Annualized Pro Forma EBITDA of the Company immediately preceding
such designation, provided, however, that if the ratio of Indebtedness to
Annualized Pro Forma EBITDA of the Company immediately preceding such
designation is 6:1 or less, then the ratio of Indebtedness to Annualized Pro
Forma EBITDA of the Company may be 0.5 greater than such ratio immediately
preceding such designation; (B) any Subsidiary which (a) has been acquired or
capitalized out of or by Equity Interests (other than Disqualified Stock) of the
Company or Capital Stock Sale Proceeds therefrom, (b) has no Indebtedness other
than Non-Recourse Debt and (c) is designated as a Non-Restricted Subsidiary by
the Board of Directors or is merged, amalgamated or consolidated with or into,
or its assets or capital stock is to be transferred to, a Non-Restricted
Subsidiary; or (C) any Subsidiary of a Non-Restricted Subsidiary.


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      "Notes" has the meaning set forth in the preamble hereto.

      "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.

      "Officers' Certificate" means a certificate signed by two Officers, one of
whom must be the Chairman of the Board, the President, the Treasurer or a Vice
President of the Company.

      "Opinion of Counsel" means a written opinion from legal counsel who is
acceptable to the Trustee. The counsel may be an employee of or counsel to the
Company or the Trustee.

      "Permitted Designee" means (i) a spouse or a child of a Permitted Holder,
(ii) trusts for the benefit of a Permitted Holder or a spouse or child of a
Permitted Holder, (iii) in the event of the death or incompetence of a Permitted
Holder, his estate, heirs, executor, administrator, committee or other personal
representative or (iv) any Person so long as a Permitted Holder owns at least
50% of the voting power of all classes of the voting stock of such Person.

      "Permitted Holders" means George S. Blumenthal, J. Barclay Knapp and their
Permitted Designees.

      "Person" means any individual, corporation, partnership, joint venture,
association, joint stock company, trust, unincorporated organization or
government or any agency or political subdivision thereof.

      "Pro Forma EBITDA" means for any Person, for any period, the EBITDA of
such Person as determined on a consolidated basis in accordance with GAAP
consistently applied after giving effect to the following: (i) if, during or
after such period, such Person or any of its Subsidiaries shall have made any
Asset Sale, Pro Forma EBITDA of such Person and its Subsidiaries for such period
shall be reduced by an amount equal to the Pro Forma EBITDA (if positive)
directly attributable to the assets which are the subject of such Asset Sale for
the period or increased by an amount equal to the Pro Forma EBITDA (if negative)
directly attributable thereto for such period and (ii) if, during or after such
period, such Person or any of its Subsidiaries completes an acquisition of any
Person or business which immediately after such acquisition is a Subsidiary of
such Person or whose assets are held directly by such Person or a Subsidiary of
such Person, Pro Forma EBITDA shall be computed so as to give pro forma effect
to the acquisition of such Person or business; and provided further that, with
respect to the Company, all of the foregoing references to "Subsidiary" or
"Subsidiaries" shall be deemed to refer only to a "Restricted Subsidiary" or
"Restricted Subsidiaries" of the Company.

      "Purchase Agreement" means the Purchase Agreement, dated as of December
10, 1998, among the Company and the Initial Purchasers.

      "Redeemable Dividend" means, for any dividend with regard to Disqualified
Stock, the quotient of the dividend divided by the difference between one and
the maximum statutory federal income tax rate (expressed as a decimal number
between 1 and 0) then applicable to the issuer of such Disqualified Stock.

      "Registration Rights Agreement" means the Registration Rights Agreement
relating to the Notes and the underlying Common Stock, dated December 16, 1998,
among the Company and the Initial Purchasers party thereto.


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<PAGE>   13

      "Restricted Subsidiary" means any Subsidiary of the Company which is not a
Non-Restricted Subsidiary.

      "Restricted Subsidiary Preferred Stock Dividend" means, for any dividend
with regard to preferred stock of a Restricted Subsidiary, the quotient of the
dividend divided by the difference between one and the maximum statutory federal
income tax rate (expressed as a decimal number between 1 and 0) then applicable
to the issuer of such preferred stock.

      "SEC" means the Securities and Exchange Commission.

      "Securities Act" means the Securities Act of 1933, as amended.

      "Senior Debt" means the principal of, interest on and other amounts due on
(i) Indebtedness of the Company, whether outstanding on the Issuance Date or
thereafter created, incurred, assumed or guaranteed by the Company, for money
borrowed from banks or other financial institutions; (ii) Indebtedness of the
Company, whether outstanding on the Issuance Date or thereafter created,
incurred, assumed or guaranteed by the Company; and (iii) Indebtedness of the
Company under interest rate swaps, caps or similar hedging agreements and
foreign exchange contracts, currency swaps or similar agreements: unless, in the
instrument creating or evidencing or pursuant to which Indebtedness under (i) or
(ii) is outstanding, it is expressly provided that such Indebtedness is not
senior in right of payment to the Notes. Senior Debt includes, with respect to
the obligations described in clauses (i) and (ii) above, interest accruing,
pursuant to the terms of such Senior Debt, on or after the filing of any
petition in bankruptcy or for reorganization relating to the Company, whether or
not post-filing interest is allowed in such proceeding, at the rate specified in
the instrument governing the relevant obligation. Notwithstanding anything to
the contrary in the foregoing, Senior Debt shall not include: (a) Indebtedness
of or amounts owed by the Company for compensation to employees, or for goods or
materials purchased in the ordinary course of business, or for services; (b)
Indebtedness of the Company to a Subsidiary of the Company; or (c) the Existing
Convertible Notes.

      "Shelf Registration Statement" shall have the meaning set forth in the
Registration Rights Agreement.

      "Subsidiary" means any corporation, association or other business entity
of which more than 50% of the total voting power of shares of Capital Stock
entitled (without regard to the occurrence of any contingency) to vote in the
election of directors, managers or trustees thereof is at the time owned or
controlled, directly or indirectly, by any Person or one or more of the other
Subsidiaries of that Person or a combination thereof.

      "TIA" means the Trust Indenture Act of 1939 (15 U.S. Code (ss.)(ss.)
77aaa-77bbbb) as in effect on the date of execution of this Indenture.

      "Trustee" means the party named as such above until a successor replaces
it in accordance with the applicable provisions of this Indenture and thereafter
means the successor.

      "Trust Officer" means the Chairman of the Board, the President or any
other officer or assistant officer of the Trustee assigned by the Trustee to
administer its corporate trust matters.

      "Wholly Owned Subsidiary" means, at any time, a Restricted Subsidiary all
of the Capital Stock of which (except directors' qualifying shares) is at the
time owned directly or indirectly by the Company.


                                       13
<PAGE>   14

Section 1.02.  Other Definitions.

<TABLE>
<CAPTION>
                                                                       Defined
Term                                                                  in Section
----                                                                  ----------
<S>                                                                       <C>
"Accredited Investor Restricted Notes"                                    2.01
"Additional Amounts"                                                      4.08
"Agent Member"                                                            2.01
"Bankruptcy Law"                                                          8.01
"Cedel"                                                                   2.01
"Change of Control Payment"                                               4.07
"Commencement Date"                                                       3.09
"Conversion Agent"                                                        2.03
"Conversion Date"                                                         5.02
"Conversion Price"                                                        5.06
"Conversion Shares"                                                       5.06
"Custodian"                                                               8.01
"Distribution Date"                                                       5.06
"Distribution Record Date"                                                5.06
"Euroclear"                                                               2.01
"Event of Default"                                                        8.01
"Global Note"                                                             2.01
"Legal Holiday"                                                          12.08
"Offer Amount"                                                            3.09
"Officer"                                                                12.11
"Paying Agent"                                                            2.03
"Payment Blockage Notice"                                                 6.02
"Payment Blockage Period"                                                 6.02
"Payment Default"                                                         8.01
"Purchase Date"                                                           3.09
"Purchase Offer"                                                          3.09
"QIBs"                                                                    2.01
"Regulation S"                                                            2.01
"Regulation S Global Note"                                                2.01
"Registrar"                                                               2.03
"Restricted Notes"                                                        2.01
"Rights"                                                                  5.06
"Rule 144A"                                                               2.01
"Rule 144A Global Note"                                                   2.01
"Tender Period"                                                           3.09
</TABLE>

Section 1.03. Incorporation by Reference of Trust Indenture Act.

      Whenever this Indenture refers to a provision of the TIA, the provision is
incorporated by 


                                       14
<PAGE>   15

reference in and made a part of this Indenture.

      The following TIA terms used in this Indenture have the following
      meanings:

      "indenture securities" means the Notes;

      "indenture security Holder" means a Holder of a Note;

      "indenture to be qualified" means this Indenture;

      "indenture trustee" or "institutional trustee" means the Trustee; and

      "obligor"  on the Notes  means the  Company or any other  obligor on the
       Notes.

      All other terms used in this Indenture that are defined by the TIA,
defined by TIA reference to another statute or defined by SEC rule under the TIA
have the meanings so assigned to them.

Section 1.04.  Rules of Construction.

      Unless the context otherwise requires:

            (a)  a term has the meaning assigned to it;

            (b) an accounting term not otherwise defined has the meaning
      assigned to it in accordance with GAAP consistently applied;

            (c) references to "GAAP" shall mean GAAP in effect as of the time
      when and for the period as to which such accounting principles are to be
      applied;

            (d)  "or" is not exclusive;

            (e) words in the singular include the plural, and in the plural
      include the singular;

            (f)  provisions apply to successive events and transactions;

            (g) references to sections of or rules under the Securities Act
      shall be deemed to include substitute, replacement or successor sections
      or rules adopted by the SEC from time to time; and

            (h) a reference to "$" or U.S. Dollars is to United States dollars.

                                   ARTICLE II.
                                    The Notes

Section 2.01.  Form and Dating.

            (a)  General.

      The Notes and the Trustee's certificate of authentication shall be
substantially in the form 


                                       15
<PAGE>   16

of Exhibit A hereto, which is hereby incorporated by
reference and expressly made a part of this Indenture. The Notes may have
notations, legends or endorsements required by law, stock exchange rule,
agreements to which the Company is subject, if any, or usage (provided that any
such notation, legend or endorsement is in a form acceptable to the Company).
The Company shall furnish any such legend not contained in Exhibit A to the
Trustee in writing. Each Note shall be dated the date of its authentication. The
Notes shall be in denominations of $1,000 and integral multiples thereof. The
terms and provisions of the Notes set forth in Exhibit A are part of this
Indenture and to the extent applicable, the Company and the Trustee, by their
execution and delivery of this Indenture, expressly agree to such terms and
provisions and to be bound thereby. However, to the extent any provision of any
Note conflicts with the express provisions of this Indenture, the provisions of
this Indenture shall govern and be controlling.

            (b) Global Notes.

      The Notes are being offered and sold by the Company pursuant to the
Purchase Agreement.

      Notes transferred in reliance on Regulation S under the Securities Act
("Regulation S"), as provided in Section 2.06(a)(ii) hereof, shall be issued in
the form of one or more permanent Global Notes in definitive, fully registered
form without interest coupons with the Global Notes Legend and Restricted Notes
Legend set forth in Exhibit A hereto (the "Regulation S Global Note"), which
shall be deposited on behalf of the transferee of the Notes represented thereby
with the Trustee, at its New York office, as custodian, for the Depositary, and
registered in the name of the Depositary or the nominee of the Depositary for
the accounts of designated agents holding on behalf of the Euroclear System
("Euroclear") or Cedel Bank, societe anonyme ("Cedel"), duly executed by the
Company and authenticated by the Trustee as hereinafter provided. The aggregate
principal amount of the Regulation S Global Note may from time to time be
increased or decreased by adjustments made on the records of the Trustee and the
Depositary or its nominee as hereinafter provided.

      Notes offered and sold to Qualified Institutional Buyers ("QIBs") in
reliance on Rule 144A under the Securities Act ("Rule 144A"), as provided in the
Purchase Agreement, shall be issued initially in the form of one or more
permanent Global Notes in definitive, fully registered form without interest
coupons with the Global Notes Legend and Restricted Notes Legend set forth in
Exhibit A hereto ("Rule 144A Global Note"), which shall be deposited on behalf
of the purchasers of the Notes represented thereby with the Trustee, at its New
York office, as custodian for the Depositary, and registered in the name of the
Depositary or a nominee of the Depositary, duly executed by the Company and
authenticated by the Trustee as hereinafter provided. The aggregate principal
amount of the Rule 144A Global Note may from time to time be increased or
decreased by adjustments made on the records of the Trustee and the Depositary
or its nominee as hereinafter provided.

            (c) Book-Entry Provisions.

      This Section 2.01(c) shall apply only to the Regulation S Global Note and
the Rule 144A Global Note issued in the form of one or more permanent Global
Notes (collectively, the "Global Notes") deposited with or on behalf of the
Depositary.

      The Company shall execute and the Trustee shall, in accordance with this
Section 2.01(c), authenticate and deliver initially one or more Global Notes
that (a) shall be registered in the name of the Depositary for such Global Note
or Global Notes or the nominee of such Depositary and (b) shall be delivered by
the Trustee to such Depositary or pursuant to such Depositary's instructions or
held by the 


                                       16
<PAGE>   17

Trustee as custodian for the Depositary.

      Members of, or participants in, the Depositary ("Agent Members") shall
have no rights under this Indenture with respect to any Global Note held on
their behalf by the Depositary or by the Trustee as the custodian of the
Depositary or under such Global Note, and the Depositary may be treated by the
Company, the Trustee and any agent of the Company or the Trustee as the absolute
owner of such Global Note for all purposes whatsoever. Notwithstanding the
foregoing, nothing herein shall prevent the Company, the Trustee or any agent of
the Company or the Trustee from giving effect to any written certification,
proxy or other authorization furnished by the Depositary or impair, as between
the Depositary and its Agent Members, the operation of customary practices of
such Depositary governing the exercise of the rights of an owner of a beneficial
interest in any Global Note.

            (d) Certificated Notes.

      Notes offered and sold to "accredited investors" (as defined in Rule 501
(a) (1), (2), (3), (4) or (7) under the Securities Act), as provided in the
Purchase Agreement, shall be issued initially in the form of one or more
certificated Notes in definitive, fully registered form without interest coupons
with the Restricted Notes Legend set forth in Exhibit A hereto ("Accredited
Investor Restricted Notes"), which shall be registered in the name of such
Accredited Investor or its nominee, duly executed by the Company and
authenticated by the Trustee as hereinafter provided. Such Accredited Investor
Restricted Notes may only be transferred in reliance on Regulation S or to QIBs
in reliance on Rule 144A.

      In addition to the provisions of Section 2.10, owners of beneficial
interests in Global Notes may, upon request to the Trustee, receive a
certificated Note, which certificated Note shall bear the Restricted Notes
Legend set forth in Exhibit A hereto (together with the Accredited Investor
Restricted Notes, the "Restricted Notes") unless otherwise provided in this
Section 2.01(d) and Section 2.06(b) hereof.

      After a transfer of any Notes during the period of the effectiveness of a
Shelf Registration Statement with respect to the Notes and pursuant thereto, all
requirements for Restricted Notes Legends on such Note will cease to apply, and
a certificated Note without a Restricted Notes Legend will be available to the
Holder of such Notes.

Section 2.02. Execution and Authentication.

      One Officer shall sign the Notes for the Company by manual or facsimile
signature.

      If an Officer whose signature is on a Note no longer holds that office at
the time the Note is authenticated, the Note shall nevertheless be valid.

      A Note shall not be valid until authenticated by the manual signature of
an authorized officer of the Trustee. The signature shall be conclusive evidence
that the Note has been authenticated under this Indenture.

      The Trustee shall, upon a written order of the Company signed by an
Officer, authenticate (1) Notes for original issue up to an aggregate principal
amount stated in paragraph 6 of the Notes. The aggregate principal amount of
Notes outstanding at any time may not exceed $600,000,000 except as provided in
Section 2.07.

      The Trustee may appoint an authenticating agent acceptable to the Company
to authenticate 


                                       17
<PAGE>   18

Notes. An authenticating agent may authenticate Notes whenever the Trustee may
do so. Each reference in this Indenture to authentication by the Trustee
includes authentication by such agent. An authenticating agent has the same
rights as an Agent to deal with Holders, the Company or an Affiliate.

Section 2.03. Registrar and Paying Agent.

      The Company shall maintain in the Borough of Manhattan, City of New York,
State of New York, (i) offices or agencies where the Notes may be presented for
registration of transfer or for exchange ("Registrar") (ii) offices or agencies
where the Notes may be presented for payment ("Paying Agent") and (iii) offices
or agencies where the Notes may be presented for conversion ("Conversion
Agent"). The Company initially designates the Trustee at its corporate trust
offices in the Borough of Manhattan, City of New York, State of New York to act
as principal Registrar, Paying Agent and Conversion Agent. The principal
Registrar shall keep a register of the Notes and of their transfer and exchange.
The Company may appoint one or more co-registrars, one or more additional paying
agents and one or more additional Conversion Agents in such other locations as
it shall determine. The term "Registrar" includes any co-registrar, the term
"Paying Agent" includes any additional paying agent and the term "Conversion
Agent" includes any additional conversion agent. The Company may change any
Paying Agent, Registrar or Conversion Agent without prior notice to any Holder.
The Company shall notify the Trustee of the name and address of any Agent not a
party to this Indenture. If the Company fails to appoint or maintain another
entity as Registrar, Paying Agent or Conversion Agent, the Trustee shall act as
such. The Company or any of its Affiliates may act as Paying Agent, Registrar or
Conversion Agent.

Section 2.04. Paying Agent to Hold Money in Trust.

      The Company shall require each Paying Agent other than the Trustee to
agree in writing that the Paying Agent will hold in trust for the benefit of
Holders or the Trustee all money held by the Paying Agent for the payment of
principal or interest on the Notes, and will notify the Trustee of any default
by the Company in making any such payment. While any such default continues, the
Trustee may require a Paying Agent to pay all money held by it to the Trustee
and to account for any money disbursed by it. The Company at any time may
require a Paying Agent to pay all money held by it to the Trustee. Upon payment
over to the Trustee, the Paying Agent (if other than the Company or an Affiliate
of the Company) shall have no further liability for the money. If the Company or
an Affiliate of the Company acts as Paying Agent, it shall segregate and hold in
a separate trust fund for the benefit of the Holders all money held by it as
Paying Agent.

Section 2.05. Holder Lists.

      The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
Holders. If the Trustee is not the Registrar, the Company shall furnish to the
Trustee on or before each interest payment date and at such other times as the
Trustee may request in writing a list in such form and as of such date as the
Trustee may reasonably require of the names and addresses of Holders.

Section 2.06.  Transfer and Exchange.

      Where Notes are presented to the Registrar or a co-registrar with a
request to register a transfer or to exchange them for an equal principal amount
of Notes of other denominations, the Registrar shall 


                                       18
<PAGE>   19

register the transfer or make the exchange if its requirements for such
transactions are met. To permit registrations of transfers and exchanges, the
Company shall issue and the Trustee shall authenticate Notes at the Registrar's
request. No service charge shall be made for any registration of transfer or
exchange (except as otherwise expressly permitted herein), but the Company may
require payment of a sum sufficient to cover any transfer tax or similar
governmental charge payable in connection therewith (other than any such
transfer tax or similar governmental charge payable upon exchanges pursuant to
Sections 2.10, 3.06 or 11.05 hereof).

      The Company shall not be required (i) to issue, register the transfer of
or exchange any Note for a period beginning at the opening of business 15 days
before the day of any selection of Notes to be redeemed under Section 3.02
hereof and ending at the close of business on the day of selection, or (ii) to
register the transfer, or exchange, of any Note so selected for redemption in
whole or in part, except the unredeemed portion of any Note being redeemed in
part.

            (a) Notwithstanding any provision to the contrary herein, so long as
      a Global Note remains outstanding and is held by or on behalf of the
      Depositary, transfers of a Global Note, in whole or in part, or of any
      beneficial interest therein, shall only be made in accordance with Section
      2.01(b) and this Section 2.06(a); provided, however, that beneficial
      interests in a Global Note may be transferred to Persons who take delivery
      thereof in the form of a beneficial interest in the same Global Note in
      accordance with the transfer restrictions set forth in the Restricted
      Notes Legend and under the heading "Notice to Investors" in the Company's
      Offering Memorandum dated December 10, 1998.

                  (i) Except for transfers or exchanges made in accordance with
            clauses (ii) through (iv) of this Section 2.06(a), transfers of a
            Global Note shall be limited to transfers of such Global Note in
            whole, but not in part, to nominees of the Depositary or to a
            successor of the Depositary or such successor's nominee.

                  (ii) Rule 144A Global Note to Regulation S Global Note. If an
            owner of a beneficial interest in the Rule 144A Global Note
            deposited with the Depositary or the Trustee as custodian for the
            Depositary wishes at any time to transfer its interest in such Rule
            144A Global Note to a Person who is required to take delivery
            thereof in the form of an interest in the Regulation S Global Note,
            such owner may, subject to the rules and procedures of the
            Depositary, exchange or cause the exchange of such interest for an
            equivalent beneficial interest in the Regulation S Global Note. Upon
            receipt by the principal Registrar of (1) instructions given in
            accordance with the Depositary's procedures from an Agent Member
            directing the principal Registrar to credit or cause to be credited
            a beneficial interest in the Regulation S Global Note in an amount
            equal to the beneficial interest in the Rule 144A Global Note to be
            exchanged, (2) a written order given in accordance with the
            Depositary's procedures containing information regarding the
            participant account of the Depositary and the Euroclear or Cedel
            account to be credited with such increase and (3) a certificate in
            the form of Exhibit B attached hereto given by the Holder of such
            beneficial interest, then the principal Registrar shall instruct the
            Depositary to reduce or cause to be reduced the principal amount of
            the Rule 144A Global Note and to increase or cause to be increased
            the principal amount of the Regulation S Global Note by the
            aggregate principal amount of the beneficial interest in the Rule
            144A Global Note equal to the beneficial interest in the Regulation
            S Global Note to be exchanged or 


                                       19
<PAGE>   20

            transferred, to credit or cause to be credited to the account of the
            Person specified in such instructions a beneficial interest in the
            Regulation S Global Note equal to the reduction in the principal
            amount of the Rule 144A Global Note and to debit or cause to be
            debited from the account of the Person making such exchange or
            transfer the beneficial interest in the Rule 144A Global Note that
            is being exchanged or transferred.

                  (iii) Regulation S Global Note to Rule 144A Global Note. If an
            owner of a beneficial interest in the Regulation S Global Note
            deposited with the Depositary or with the Trustee as custodian for
            the Depositary wishes at any time to transfer its interest in such
            Regulation S Global Note to a Person who is required to take
            delivery thereof in the form of an interest in the Rule 144A Global
            Note, such Holder may, subject to the rules and procedures of
            Euroclear or Cedel, as the case may be, and the Depositary, exchange
            or cause the exchange of such interest for an equivalent beneficial
            interest in the Rule 144A Global Note. Upon receipt by the principal
            Registrar of (1) instructions from Euroclear or Cedel, if
            applicable, and the Depositary, directing the principal Registrar to
            credit or cause to be credited a beneficial interest in the Rule
            144A Global Note equal to the beneficial interest in the Regulation
            S Global Note to be exchanged or transferred, (2) a written order
            given in accordance with the Depositary's procedures containing
            information regarding the participant account of the Depositary and
            (3) a certificate in the form of Exhibit C attached hereto given by
            the owner of such beneficial interest, then Euroclear or Cedel or
            the principal Registrar, as the case may be, will instruct the
            Depositary to reduce or cause to be reduced the Regulation S Global
            Note and to increase or cause to be increased the principal amount
            of the Rule 144A Global Note by the aggregate principal amount of
            the beneficial interest in the Regulation S Global Note to be
            exchanged or transferred, and the principal Registrar shall instruct
            the Depositary, concurrently with such reduction, to credit or cause
            to be credited to the account of the Person specified in such
            instructions a beneficial interest in the Rule 144A Global Note
            equal to the reduction in the principal amount of the Regulation S
            Global Note and to debit or cause to be debited from the account of
            the Person making such exchange or transfer the beneficial interest
            in the Regulation S Global Note that is being exchanged or
            transferred.

                  (iv) Global Note to Restricted Note. If an owner of a
            beneficial interest in a Global Note deposited with the Depositary
            or with the Trustee as custodian for the Depositary wishes at any
            time to transfer its interest in such Global Note to a Person who is
            required to take delivery thereof in the form of a Restricted Note,
            such owner may, subject to the rules and procedures of Euroclear or
            Cedel, if applicable, and the Depositary, cause the exchange of such
            interest for one or more Restricted Notes of any authorized
            denomination or denominations and of the same aggregate principal
            amount. Upon receipt by the principal Registrar of (1) instructions
            from Euroclear or Cedel, if applicable, and the Depositary directing
            the principal Registrar to authenticate and deliver one or more
            Restricted Notes of the same aggregate principal amount as the
            beneficial interest in the Global Note to be exchanged, such
            instructions to contain the name or names of the designated
            transferee or transferees, the authorized denomination or
            denominations of the Restricted Notes to be so issued and
            appropriate delivery instructions, (2) a certificate in the form of
            Exhibit D 


                                       20
<PAGE>   21

            attached hereto given by the owner of such beneficial interest to
            the effect set forth therein, (3) a certificate in the form of
            Exhibit E attached hereto given by the Person acquiring the
            Restricted Notes for which such interest is being exchanged, to the
            effect set forth therein, and (4) such other certifications, legal
            opinions or other information as the Company may reasonably require
            to confirm that such transfer is being made pursuant to an exemption
            from, or in a transaction not subject to, the registration
            requirements of the Securities Act, then Euroclear or Cedel, if
            applicable, or the principal Registrar, as the case may be, will
            instruct the Depositary to reduce or cause to be reduced such Global
            Note by the aggregate principal amount of the beneficial interest
            therein to be exchanged and to debit or cause to be debited from the
            account of the Person making such transfer the beneficial interest
            in the Global Note that is being transferred, and concurrently with
            such reduction and debit the Company shall execute, and the Trustee
            shall authenticate and deliver, one or more Restricted Notes of the
            same aggregate principal amount in accordance with the instructions
            referred to above.

                  (v) Restricted Note to Restricted Note. If a Holder of a
            Restricted Note wishes at any time to transfer such Restricted Note
            to a Person who is required to take delivery thereof in the form of
            a Restricted Note, such Holder may, subject to the restrictions on
            transfer set forth herein and in such Restricted Note, cause the
            exchange of such Restricted Note for one or more Restricted Notes of
            any authorized denomination or denominations and of the same
            aggregate principal amount. Upon receipt by the principal Registrar
            of (1) such Restricted Note, duly endorsed as provided herein, (2)
            instructions from such Holder directing the principal Registrar to
            authenticate and deliver one or more Restricted Notes of the same
            aggregate principal amount as the Restricted Note to be exchanged,
            such instructions to contain the name or authorized denomination or
            denominations of the Restricted Notes to be so issued and
            appropriate delivery instructions, (3) a certificate from the Holder
            of the Restricted Note to be exchanged in the form of Exhibit D
            attached hereto, (4) a certificate in the form of Exhibit E attached
            hereto given by the Person acquiring the Restricted Notes for which
            such interest is being exchanged, to the effect set forth therein,
            and (5) such other certifications, legal opinions or other
            information as the Company may reasonably require to confirm that
            such transfer is being made pursuant to an exemption from, or in a
            transaction not subject to, the registration requirements of the
            Securities Act, then the Registrar shall cancel or cause to be
            canceled such Restricted Note and concurrently therewith, the
            Company shall execute, and the Trustee shall authenticate and
            deliver, one or more Restricted Notes of the same aggregate
            principal amount, in accordance with the instructions referred to
            above.

                  (vi) Restricted Note to Rule 144A Note. If an owner of a
            Restricted Note registered in the name of such owner wishes at any
            time to transfer such Restricted Note to a Person who is required to
            take delivery thereof in the form of an interest in the Rule 144A


                                       21
<PAGE>   22

            Global Note, such Holder may, subject to the rules and procedures of
            the Depositary, exchange or cause the exchange of such Restricted
            Note for an equivalent beneficial interest in the Rule 144A Global
            Note. Upon receipt by the principal Registrar of (1) instructions
            from the Company, directing the principal Registrar (A) to credit or
            cause to be credited a beneficial interest in the Rule 144A Global
            Note equal to the principal amount of the Restricted Note to be
            exchanged or transferred and (B) to cancel such Restricted Note to
            be exchanged or transferred, (2) a written order given in accordance
            with the Depositary's procedures containing information regarding
            the participant account of the Depositary and (3) a certificate in
            the form of Exhibit C attached hereto given by the owner of such
            Restricted Note, then the principal Registrar will instruct the
            Trustee to cancel such Restricted Note and will instruct the
            Depositary to increase or cause to be increased the principal amount
            of the Rule 144A Global Note by the principal amount of the
            Restricted Note to be exchanged or transferred, and the principal
            Registrar shall instruct the Depositary, concurrently with such
            cancellation of the Restricted Note, to credit or cause to be
            credited to the account of the Person specified in such instructions
            a beneficial interest in the Rule 144A Global Note equal to the
            principal amount of the Restricted Note to be canceled by the
            Trustee.

                  (vii) Restricted Note to Regulation S Global Note. If an owner
            of a Restricted Note registered in the name of such owner wishes at
            any time to transfer such Restricted Note to a Person who is
            required to take delivery thereof in the form of an interest in the
            Regulation S Global Note, such owner may, subject to the rules and
            procedures of the Euroclear or Cedel, as the case may be, exchange
            or cause the exchange of such Restricted Note for an equivalent
            beneficial interest in the Regulation S Global Note. Upon receipt by
            the principal Registrar of (1) instructions from the Company,
            directing the principal Registrar (A) to credit or cause to be
            credited a beneficial interest in the Regulation S Global Note equal
            to the principal amount of the Restricted Note to be exchanged or
            transferred and (B) to cancel such Restricted Note to be exchanged
            or transferred, (2) a written order given in accordance with the
            Depositary's procedures containing information regarding the
            participant account of the Euroclear or Cedel account to be credited
            with such increase and (3) a certificate in the form of Exhibit B
            attached hereto given by the Holder of such Restricted Note, then
            the principal Registrar will instruct the Trustee to cancel such
            Restricted Note and will instruct the Depositary to increase or
            cause to be increased the principal amount of the Regulation S
            Global Note by the principal amount of the Restricted Note to be
            exchanged or transferred, and the principal Registrar shall instruct
            the Depositary, concurrently with such cancellation of the
            Restricted Note, to credit or cause to be credited to the account of
            the Person specified in such instructions a beneficial interest in
            the Regulation S Global Note equal to the principal amount of the
            Restricted Note to be cancelled by the Trustee.

                  (viii) Other Exchanges. In the event that a beneficial
            interest in a Global Note is exchanged for a certificated Note in
            definitive registered form pursuant to Section 2.10, prior to the
            effectiveness of a Shelf Registration Statement with respect to such
            Notes, such Notes may be exchanged only in accordance with such
            procedures as are substantially consistent with the provisions of
            clauses (ii) through (v) above (including the certification
            requirements intended to ensure that such transfers comply with Rule
            144A, Rule 144, Regulation S or any other available exemption from
            registration, as the case may be) and such other procedures as may
            from time to time be adopted by the Company.

            (b) Except in connection with a Shelf Registration Statement
      contemplated by and in 


                                       22
<PAGE>   23

      accordance with the terms of the Registration Rights Agreement, if Notes
      are issued upon the transfer, exchange or replacement of Notes bearing the
      Restricted Securities Legend set forth in Exhibit A hereto, or if a
      request is made to remove such Restricted Notes Legend on Notes, the Notes
      so issued shall bear the Restricted Notes Legend, or the Restricted Notes
      Legend shall not be removed, as the case may be, unless there is delivered
      to the Company such satisfactory evidence, which may include an opinion of
      counsel licensed to practice law in the State of New York, as may be
      reasonably required by the Company, that neither the legend nor the
      restrictions on transfer set forth therein are required to ensure that
      transfers thereof comply with the provisions of Rule 144A, Rule 144,
      Regulation S or any other available exemption from registration under the
      Securities Act or, with respect to Restricted Notes, that such Notes are
      not "restricted" within the meaning of Rule 144 under the Securities Act.
      Upon provision of such satisfactory evidence, the Trustee, at the
      direction of the Company, shall authenticate and deliver Notes that do not
      bear the legend.

            (c) Neither the Company nor the Trustee shall have any
      responsibility for any actions taken or not taken by the Depositary and
      the Company shall have no responsibility for any actions taken or not
      taken by the Trustee as agent or custodian of the Depositary.

Section 2.07. Replacement Notes.

      If the Holder of a Note claims that the Note has been lost, destroyed or
wrongfully taken or if such Note is mutilated and is surrendered to the Trustee,
the Company shall issue and the Trustee shall authenticate a replacement Note if
the Trustee's and the Company's requirements are met. If required by the Trustee
or the Company, an indemnity bond must be sufficient in the judgment of both to
protect the Company, the Trustee, any Agent or any authenticating agent from any
loss which any of them may suffer if a Note is replaced. The Company may charge
for its expenses in replacing a Note.

      In case any such mutilated, destroyed, lost or stolen Note has become or
is about to become due and payable, or is about to be purchased by the Company
pursuant to Article III hereof, the Company in its discretion may, instead of
issuing a new Note, pay or purchase such Note, as the case may be.

      Every replacement Note is an additional obligation of the Company and
shall be entitled to all of the benefits of this Indenture equally and
proportionately with all other Notes duly issued hereunder.

Section 2.08. Outstanding Notes.

      The Notes outstanding at any time are all the Notes authenticated by the
Trustee except for those canceled by it, those delivered to it for cancellation,
and those described in this Section as not outstanding.

      If a Note is replaced, paid or purchased pursuant to Section 2.07 hereof,
it ceases to be outstanding unless the Trustee receives proof satisfactory to it
that the replaced, paid or purchased Note is held by a bona fide purchaser.

      If the principal amount of any Note is considered paid under Section 4.01
hereof, it ceases to be outstanding and interest on it ceases to accrue.

      Except as set forth in Section 2.09 hereof, a Note does not cease to be
outstanding because the Company or an Affiliate of the Company holds the Note.


                                       23
<PAGE>   24

Section 2.09. Treasury Notes.

      In determining whether the Holders of the required principal amount of
Notes have concurred in any direction, waiver or consent, Notes owned by the
Company or an Affiliate of the Company shall be considered as though they are
not outstanding, except that for the purposes of determining whether the Trustee
shall be protected in relying on any such direction, waiver or consent, only
Notes that the Trustee knows are so owned shall be so disregarded.

Section 2.10. Temporary Notes; Global Notes.

            (a) Until definitive Notes are ready for delivery, the Company may
      prepare and the Trustee shall authenticate temporary Notes. Temporary
      Notes shall be substantially in the form of definitive Notes but may have
      variations that the Company considers appropriate for temporary Notes.
      Without unreasonable delay, the Company shall prepare and the Trustee
      shall authenticate definitive Notes in exchange for temporary Notes.
      Holders of temporary Notes shall be entitled to all of the benefits of
      this Indenture.

            (b) A Global Note deposited with the Depositary or with the Trustee
      as custodian for the Depositary pursuant to Section 2.01 shall be
      transferred to the beneficial owners thereof in the form of certificated
      Notes only in accordance with Section 2.01(d) or if such transfer complies
      with Section 2.06 and (i) the Depositary notifies the Company that it is
      unwilling or unable to continue as Depositary for such Global Note or if
      at any time such Depositary ceases to be a "clearing agency" registered
      under the Exchange Act and a successor depositary is not appointed by the
      Company within 90 days of such notice, or (ii) an Event of Default has
      occurred and is continuing.

            (c) Any Global Note that is transferable to the beneficial owners
      thereof in the form of certificated Notes pursuant to Section 2.01(d) or
      to this Section 2.10 shall be surrendered by the Depositary to the Trustee
      to be so transferred, in whole or from time to time in part, without
      charge, and the Trustee shall authenticate and deliver, upon such transfer
      of each portion of such Global Note, an equal aggregate principal amount
      of Notes of authorized denominations in the form of certificated Notes.
      Any portion of a Global Note transferred pursuant to this Section 2.10
      shall be executed, authenticated and delivered only in denominations of
      $1,000 and any integral multiple thereof and registered in such names as
      the Depositary shall direct. Any Note in the form of certificated Notes
      delivered in exchange for an interest in the Global Notes shall, except as
      otherwise provided by Section 2.06(b) bear the Restricted Notes Legend set
      forth in Exhibit A hereto.

            (d) The registered Holder of a Global Note may grant proxies and
      otherwise authorize any Person, including Agent Members and Persons that
      may hold interests through Agent Members, to take any action which a
      Holder is entitled to take under this Indenture or the Notes.

            (e) In the event of the occurrence of either of the events specified
      in Section 2.10(b), the Company will promptly make available to the
      Trustee a reasonable supply of certificated Notes in definitive, fully
      registered form without interest coupons.

Section 2.11. Cancellation.


                                       24
<PAGE>   25

      The Company at any time may deliver Notes to the Trustee for cancellation.
The Registrar, Paying Agent and Conversion Agent shall forward to the Trustee
any Notes surrendered to them for registration of transfer, exchange or payment.
The Trustee shall promptly cancel all Notes surrendered for registration of
transfer, exchange, payment, conversion, replacement or cancellation and shall
dispose of canceled Notes as the Company directs. The Company may not issue new
Notes to replace Notes that it has paid or that have been delivered to the
Trustee for cancellation.

Section 2.12. Defaulted Interest.

      If the Company fails to make a payment of interest on the Notes, it shall
pay such defaulted interest plus any interest payable on the defaulted interest,
in any lawful manner. It may pay such defaulted interest, plus any such interest
payable on it, to the Persons who are Holders on a subsequent special record
date. The Company shall fix any such record date and payment date, provided that
no such record date shall be less than 10 days prior to the related payment date
for such defaulted interest. At least 15 days before any such record date, the
Company shall mail to Holders a notice that states the special record date, the
related payment date and amount of such interest to be paid.

                                  ARTICLE III.
                                   Redemption

Section 3.01. Notices to Trustee.

      If the Company elects to redeem Notes pursuant to the optional redemption
provisions of the Notes and Section 3.07 hereof or pursuant to the Optional Tax
Redemption provision of the Notes (Section 8 of the Notes), it shall notify the
Trustee of the redemption date and the principal amount of Notes to be redeemed,
and in connection with an Optional Tax Redemption as provided in the Notes, such
notice shall be accompanied by an Officers' Certificate to the effect that the
conditions to such redemption contained herein have been complied with. The
Company shall give each notice provided for in this Section 3.01 at least 50
days before the redemption date (unless a shorter notice period shall be
satisfactory to the Trustee).

Section 3.02. Selection of Notes to Be Redeemed.

      If less than all of the Notes are to be redeemed at any time, selection of
Notes shall be made by the Trustee on a pro rata basis or by lot or by method
that complies with the requirements of any exchange on which the Notes are
listed and that the Trustee considers fair and appropriate, provided that no
Notes of $1,000 or less shall be redeemed in part. The Trustee shall make the
selection not more than 60 days and not less than 30 days before the redemption
date from Notes outstanding not previously called for redemption. Notes and
portions of Notes selected shall be in amounts of $1,000 or integral multiples
of $1,000. Provisions of this Indenture that apply to Notes called for
redemption also apply to portions of Notes called for redemption. The Trustee
shall notify the Company promptly of the Notes or portions of Notes to be called
for redemption.

      If any Note selected for partial redemption is converted in part after
such selection, the converted portion of such Note shall be deemed (so far as
may be) to be the portion to be selected for redemption. The Notes (or portions
thereof) so selected shall be deemed duly selected for redemption for all
purposes hereunder, notwithstanding that any such Note is converted in whole or
in part before the mailing of the notice of redemption. Upon any redemption of
less than all the Notes, the Company and the Trustee may 


                                       25
<PAGE>   26

treat as outstanding any Notes surrendered for conversion during the period 15
days next preceding the mailing of a notice of redemption and need not treat as
outstanding any Note authenticated and delivered during such period in exchange
for the unconverted portion of any Note converted in part during such period.

Section 3.03. Notice of Redemption.

      At least 30 days but not more than 60 days before a redemption date, the
Company shall mail, by first class mail, a notice of redemption to each Holder
whose Notes are to be redeemed at its registered address. The notice shall
identify the Notes to be redeemed and shall state:

            (a) the redemption date;

            (b) the redemption price;

            (c) if any Note is to be redeemed in part only, the portion of the
      principal amount thereof redeemed, and that, after the redemption date,
      upon surrender of such Note, a new Note in principal amount equal to the
      unredeemed portion thereof shall be issued in the name of the Holder
      thereof upon cancellation of the original Note;

            (d) the name and address of the Paying Agent;

            (e) that Notes called for redemption must be surrendered to the
      Paying Agent to collect the redemption price plus accrued interest, if
      any, and Liquidated Damages, if any;

            (f) that interest on Notes called for redemption ceases to accrue on
      and after the redemption date; and

            (g) the paragraph of the Notes pursuant to which the Notes called
      for redemption are being redeemed.

      Such notice shall also state the current Conversion Price and the date on
which the right to convert such Notes or portions thereof into Common Stock of
the Company will expire.

      At the Company's request, the Trustee shall give notice of redemption in
the Company's name and at its expense; provided that the Company shall have
delivered to the Trustee, at least 45 days prior to the redemption date, an
Officers' Certificate requesting that the Trustee give such notice and setting
forth the information to be stated in such notice, as provided in the preceding
paragraph.

Section 3.04. Effect of Notice of Redemption.

      Once notice of redemption is mailed in accordance with Section 3.03
hereof, Notes called for redemption become due and payable on the redemption
date at the price set forth in the Note. A notice of redemption may not be
conditional.

Section 3.05. Deposit of Redemption Price.

      On or before the redemption date, the Company shall deposit with the
Trustee or with the Paying Agent money sufficient to pay the redemption price of
and accrued interest on all Notes to be redeemed 


                                       26
<PAGE>   27

on that date unless theretofore converted into Common Stock pursuant to the
provisions hereof. The Trustee or the Paying Agent shall return to the Company
any money not required for that purpose.

Section 3.06. Notes Redeemed in Part.

      Upon surrender of a Note that is redeemed in part, the Company shall issue
and the Trustee shall authenticate for the Holder at the expense of the Company
a new Note equal in principal amount to the unredeemed portion of the Note
surrendered.

Section 3.07. Optional Redemption and Optional Tax Redemption.

      The Company may redeem all or any portion of the Notes, upon the terms and
at the redemption prices set forth in the Notes. The Company may also redeem all
of the Notes in accordance with the Optional Tax Redemption provision of the
Notes (Section 8 of the Notes). Any redemption pursuant to this Section 3.07
shall be made pursuant to the provisions of Section 3.01 through 3.06 hereof.

Section 3.08. Mandatory Redemption

      The Company shall not be required to make mandatory redemption payments
with respect to the Notes.

Section 3.09. Purchase Offer.

            (a) In the event that, pursuant to 4.07 hereof, the Company shall
      commence an offer to all Holders of the Notes to purchase Notes (the
      "Purchase Offer"), the Company shall follow the procedures in this Section
      3.09.

            (b) The Purchase Offer shall remain open for a period specified by
      the Company which shall be no less than 30 calendar days and no more than
      40 calendar days following its commencement (the "Commencement Date") (as
      determined in accordance with Section 4.07 hereof), except to the extent
      that a longer period is required by applicable law (the "Tender Period").
      Upon the expiration of the Tender Period (the "Purchase Date"), the
      Company shall purchase the principal amount of all of the Notes required
      to be purchased pursuant to Section 4.07 hereof (the "Offer Amount").

            (c) If the Purchase Date is on or after an interest payment record
      date and on or before the related interest payment date, any accrued
      interest shall be paid to the Person in whose name a Note is registered at
      the close of business on such record date, and no additional interest will
      be payable to Holders who tender Notes pursuant to the Purchase Offer.

            (d) The Company shall provide the Trustee with notice of the
      Purchase Offer at least 10 days before the Commencement Date.

            (e) On or before the Commencement Date, the Company or the Trustee
      (at the expense of the Company) shall send, by first class mail, a notice
      to each of the Holders, which shall govern the terms of the Purchase Offer
      and shall state:

                  (i) that the Purchase Offer is being made pursuant to this
            Section 3.09 and Section 4.07 hereof and the length of time the
            Purchase Offer will remain open;


                                       27
<PAGE>   28

                  (ii) The purchase price (as determined in accordance with
            Section 4.07 hereof) and the Purchase Date, and that all Notes
            tendered will be accepted for payment;

                  (iii) that any Note or portion thereof not tendered or
            accepted for payment will continue to accrue interest;

                  (iv)that, unless the Company defaults in the payment of the
            purchase price, any Note or portion thereof accepted for payment
            pursuant to the Purchase Offer will cease to accrue interest after
            the Purchase Date;

                  (v) that Holders electing to have a Note or portion thereof
            purchased pursuant to any Purchase Offer will be required to
            surrender the Note, with the form entitled "Option of Holder to
            Elect Purchase" on the reverse of the Note completed, to the
            Company, a depositary, if appointed by the Company, or a Paying
            Agent at the address specified in the notice prior to the close of
            business on the third Business Day preceding the Purchase Date;

                  (vi) that Holders will be entitled to withdraw their election
            if the Company, depositary or Paying Agent, as the case may be,
            receives, not later than the close of business on the second
            Business Day preceding the Purchase Date, or such longer period as
            may be required by law, a letter or a telegram, telex or facsimile
            transmission (receipt of which is confirmed and promptly followed by
            a letter) setting forth the name of the Holder, the principal amount
            of the Note or portion thereof the Holder delivered for purchase and
            a statement that such Holder is withdrawing his election to have the
            Note or portion thereof purchased;

                  (vii) that Holders whose Notes were purchased only in part
            will be issued new Notes equal in principal amount to the
            unpurchased portion of the Notes surrendered.

      In addition, the notice shall, to the extent permitted by applicable law,
be accompanied by a copy of the information regarding the Company and its
Subsidiaries which is required to be contained in the most recent Quarterly
Report on Form 10-Q or Annual Report on Form 10-K (including any financial
statements or other information required to be included or incorporated by
reference therein) and any Reports on Form 8-K filed since the date of such
Quarterly Report or Annual Report (or would have been required to file if the
Company remained a company incorporated in the United States), as the case may
be, which the Company has filed (or would have been required to file if it
remained a company incorporated in the United States) with the SEC on or prior
to the date of the notice. The notice shall contain all instructions and
materials necessary to enable such Holders to tender Notes pursuant to the Asset
Sale Offer or the Purchase Offer, as the case may be.

            (f) At least one Business Day prior to the Purchase Date, the
      Company shall irrevocably deposit with the Trustee or a Paying Agent in
      immediately available funds an amount equal to the Offer Amount to be held
      for payment in accordance with the terms of this Section 3.09. On the
      Purchase Date, the Company shall, to the extent lawful, (i) accept for
      payment the Notes or portions thereof tendered pursuant to the Purchase
      Offer, (ii) deliver or cause the depositary or Paying Agent to deliver to
      the Trustee Notes so accepted and (iii) deliver to the Trustee an
      Officers' Certificate stating such Notes or portions thereof have been
      accepted for 


                                       28
<PAGE>   29

      payment by the Company in accordance with the terms of this Section 3.09.
      The Depositary, the Paying Agent or the Company, as the case may be, shall
      promptly (but in any case not later than ten (10) calendar days after the
      Purchase Date) mail or deliver to each tendering Holder an amount equal to
      the purchase price of the Notes tendered by such Holder and accepted by
      the Company for purchase, and the Trustee shall promptly authenticate and
      mail or deliver to such Holders a new Note equal in principal amount to
      any unpurchased portion of the Note surrendered. Any Notes not so accepted
      shall be promptly mailed or delivered by or on behalf of the Company to
      the Holder thereof. The Company will publicly announce in a newspaper of
      general circulation the results of the Purchase Offer on the Purchase
      Date.

            (g) The Purchase Offer shall be made by the Company in compliance
      with all applicable provisions of the Exchange Act, and all applicable
      tender offer rules promulgated thereunder, and shall include all
      instructions and materials necessary to enable such Holders to tender
      their Notes.

                                   ARTICLE IV.
                                    Covenants

Section 4.01. Payment of Notes.

      The Company shall pay the principal of, premium, if any, Liquidated
Damages, if any, and interest on, the Notes on the dates and in the manner
provided in the Notes. Principal, premium, if any, Liquidated Damages, if any,
and interest shall be considered paid on the date due if the Paying Agent (other
than the Company or an Affiliate of the Company) holds on that date money
designated for and sufficient to pay all principal, premium, if any, Liquidated
Damages, if any, and interest then due. To the extent lawful, the Company shall
pay interest (including post-petition interest in any proceeding under any
Bankruptcy Law) on (i) overdue principal and premium, if any, at the rate borne
by the Notes, compounded semiannually; and (ii) overdue installments of interest
or Liquidated Damages, if any, (without regard to any applicable grace period)
at the same rate, compounded semiannually.

Section 4.02. Reports.

      Whether or not required by the rules and regulations of the SEC, so long
as any Notes are outstanding, the Company shall file with the SEC and furnish to
the Trustee and to the Holders of Notes, all quarterly and annual financial
information required to be contained in a filing with the SEC on Forms 10-Q and
10-K (or the equivalent thereof under the Exchange Act for foreign private
issuers in the event the Company becomes a corporation organized under the laws
of the United Kingdom, the Netherlands, the Netherlands Antilles, Bermuda or the
Cayman Islands), including a "Management's Discussion and Analysis of Results of
Operations and Financial Condition" and, with respect to the annual information
only, a report thereon by the Company's certified independent accountants, in
each case, as required by the rules and regulations of the SEC as in effect on
the Issuance Date. This Section 4.02 will apply notwithstanding that the Company
becomes a corporation organized under the laws of the United Kingdom, the
Netherlands, the Netherlands Antilles, Bermuda or the Cayman Islands.

Section 4.03. Compliance Certificate.

      The Company shall deliver to the Trustee, within 90 days after the end of
each fiscal year of the Company, an Officers' Certificate stating that a review
of the activities of the Company and its 


                                       29
<PAGE>   30

subsidiaries during the preceding fiscal year has been made under the
supervision of the signing Officers with a view to determining whether the
Company has kept, observed, performed and fulfilled its obligations under, and
complied with the covenants and conditions contained in, this Indenture, and
further stating, as to each such Officer signing such certificate, that to the
best of his knowledge the Company has kept, observed, performed and fulfilled
each and every covenant, and complied with the covenants and conditions
contained in this Indenture and is not in default in the performance or
observance of any of the terms, provisions and conditions hereof (or, if a
Default or Event of Default shall have occurred, describing all such Defaults or
Events of Default of which he may have knowledge) and that to the best of his
knowledge no event has occurred and remains in existence by reason of which
payments on account of the principal or of interest, if any, on the Notes are
prohibited.

      One of the Officers signing such Officers' Certificate shall be either the
Company's principal executive officer, principal financial officer or principal
accounting officer.

      The Company will so long as any of the Notes are outstanding, deliver to
the Trustee, forthwith upon becoming aware of any Default or Event of Default an
Officers' Certificate specifying such Default or Event of Default.

      Immediately upon the occurrence of any Registration Default giving rise to
Liquidated Damages or the cure of any such Registration Default, the Company
shall give the Trustee notice thereof and of the event giving rise to such
Registration Default or the cure of any such Registration Default (such notice
to be contained in an Officers' Certificate) and prior to receipt of such
Officers' Certificate the Trustee shall be entitled to assume that no such
Registration Default has occurred or been cured, as the case may be.

Section 4.04. Stay, Extension and Usury Laws.

      The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, plead, or in any manner whatsoever claim or
take the benefit or advantage of, any stay, extension or usury law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent it may
lawfully do so) hereby expressly waives all benefit or advantage of any such
law, and covenants that it will not, by resort to any such law, hinder, delay or
impede the execution of any power herein granted to the Trustee, but will suffer
and permit the execution of every such power as though no such law had been
enacted.

Section 4.05. Corporate Existence.

      Subject to Article VII hereof, the Company will do or cause to be done all
things necessary to preserve and keep in full force and effect its corporate
existence and the corporate, partnership or other existence of each subsidiary
of the Company in accordance with the respective organizational documents of
each subsidiary and the rights (charter and statutory), licenses and franchises
of the Company and its subsidiaries; provided, however, that the Company shall
not be required to preserve any such right, license or franchise, or the
corporate, partnership or other existence of any subsidiary, if the Board of
Directors shall determine that the preservation thereof is no longer desirable
in the conduct of the business of the Company and its subsidiaries taken as a
whole and that the loss thereof is not adverse in any material respect to the
Holders. The Company shall notify the Trustee in writing of any subsidiary which
qualifies as a Material Subsidiary and is not specified in clause (i) of the
definition thereof.

Section 4.06. Taxes.


                                       30
<PAGE>   31

      The Company shall, and shall cause each of its subsidiaries to, pay prior
to delinquency all taxes, assessments and governmental levies, except as
contested in good faith and by appropriate proceedings.

Section 4.07. Change of Control.

            (a) Upon the occurrence of a Change of Control, each Holder of Notes
      shall have the right to require the Company to repurchase all or any part
      (equal to $1,000 or an integral multiple thereof) of such Holder's Notes
      pursuant to the Purchase Offer at a purchase price equal to 101% of the
      principal amount thereof plus accrued and unpaid interest and Liquidated
      Damages thereon, if any, to the date of purchase (the "Change of Control
      Payment").

            (b) Within 40 days following any Change of Control, the Company
      shall mail to each Holder the notice provided by Section 3.09(e).

Section 4.08. Payment of Additional Amounts.

      At least 10 days prior to the first date on which payment of principal and
any premium, Liquidated Damages or interest on the Notes is to be made, and at
least 10 days prior to any subsequent such date if there has been any change
with respect to the matters set forth in the Officers' Certificate described in
this Section 4.08, the Company shall furnish the Trustee and the Paying Agent,
if other than the Trustee, with an Officers' Certificate instructing the Trustee
and the Paying Agent whether the Company is obligated to pay Additional Amounts
(as defined in Section 3 of the Notes) with respect to such payment of
principal, or of any premium or interest or Liquidated Damages, if any, on the
Notes. If the Company will be obligated to pay Additional Amounts with respect
to such payment then such Officers' Certificate shall specify by country the
amount, if any, required to be withheld on such payments to such Holders and the
Company will pay to the Trustee or the Paying Agent such Additional Amounts. The
Company shall indemnify the Trustee and the Paying Agent for, and hold them
harmless against, any loss, liability or expense reasonably incurred without
negligence or bad faith on their part arising out of or in connection with
actions taken or omitted by any of them in reliance on any Officers' Certificate
furnished to them pursuant to this Section 4.08.

      Whenever in this Indenture or the Notes there is mentioned, in any
context, the payment of principal (and premium, if any), Offer Amount, interest
or any other amount payable, including Liquidated Damages, under or with respect
to any Note such mention shall be deemed to include mention of the payment of
Additional Amounts provided for in this Section 4.08 and Section 3 of the Notes
to the extent that, in such context, Additional Amounts are, were or would be
payable in respect thereof pursuant to the provisions of this Section 4.08 and
Section 3 of the Notes and express mention of the payment of Additional Amounts
(if applicable) in any provisions hereof shall not be construed as excluding
Additional Amounts in those provisions hereof where such express mention is not
made (if applicable).

                                   ARTICLE V.
                                   Conversion

Section 5.01. Conversion Privilege.

      A Holder of a Note may convert it into fully paid and nonassessable shares
of Common Stock at any time after 90 days following the Issuance Date and prior
to maturity at the Conversion Price then in 


                                       31
<PAGE>   32

effect, except that, with respect to any Note called for redemption, such
conversion right shall terminate at the close of business on the Business Day
immediately preceding the redemption date (unless the Company shall default in
making the redemption payment when it becomes due, in which case the conversion
right shall terminate on the date such default is cured). The number of shares
of Common Stock issuable upon conversion of a Note is determined by dividing the
principal amount of such Note by the conversion price in effect on the
Conversion Date (the "Conversion Price").

      The initial Conversion Price is stated in paragraph 13 of the Notes and is
subject to adjustment as provided in this Article V.

      A holder may convert a portion of a Note equal to any integral multiple of
$1,000. Provisions of this Indenture that apply to conversion of all of a Note
also apply to conversion of a portion of it.

Section 5.02. Conversion Procedure.

      To convert a Note, a holder must satisfy the requirements in paragraph 13
of the Notes. The date on which the holder satisfies all of those requirements
is the conversion date (the "Conversion Date"). As soon as practicable after the
Conversion Date, the Company shall deliver to the Holder through the Conversion
Agent a certificate for the number of whole shares of Common Stock issuable upon
the conversion and a check for any fractional share determined pursuant to
Section 5.03 hereof. The Person in whose name the certificate is registered
shall become the stockholder of record on the Conversion Date and, as of such
date, such Person's rights as a Holder shall cease; provided, however, that no
surrender of a Note on any date when the stock transfer books of the Company
shall be closed shall be effective to constitute the Person entitled to receive
the shares of Common Stock upon such conversion as the stockholder of record of
such shares of Common Stock on such date, but such surrender shall be effective
to constitute the Person entitled to receive such shares of Common Stock as the
stockholder of record thereof for all purposes at the close of business on the
next succeeding day on which such stock transfer books are open; provided
further, however, that such conversion shall be at the Conversion Price in
effect on the date that such Note shall have been surrendered for conversion, as
if the stock transfer books of the Company had not been closed.

      No payment or adjustment will be made for accrued and unpaid interest or
Liquidated Damages, if any, on a converted Note or for dividends or
distributions on shares of Common Stock issued upon conversion of a Note, but if
any holder surrenders a Note for conversion after the close of business on the
record date for the payment of an installment of interest and prior to the
opening of business on the next interest payment date, then, notwithstanding
such conversion, the interest payable on such interest payment date shall be
paid to the holder of such Note on such record date. In such event, such Note,
when surrendered for conversion, need not be accompanied by payment of an amount
equal to the interest payable on such interest payment date on the portion so
converted.

      If a holder converts more than one Note at the same time, the number of
whole shares of Common Stock issuable upon the conversion shall be based on the
total principal amount of Notes converted.

      Upon surrender of a Note that is converted in part, the Trustee shall
authenticate for the holder a new Note equal in principal amount to the
unconverted portion of the Note surrendered.

Section 5.03. Fractional Shares.


                                       32
<PAGE>   33

      The Company will not issue fractional shares of Common Stock upon
conversion of a Note. In lieu thereof, the Company will pay an amount in cash
based upon the Daily Market Price of the Common Stock on the trading day prior
to the date of conversion.

Section 5.04. Taxes in Conversion.

      The issuance of certificates for shares of Common Stock upon the
conversion of any Note shall be made without charge to the converting Holder for
such certificates or for any tax in respect of the issuance of such
certificates, and such certificates shall be issued in the respective names of,
or in such names as may be directed by, the Holder or Holders of the converted
Note; provided, however, that in the event that certificates for shares of
Common Stock are to be issued in a name other than the name of the holder of the
Note converted, such Note, when surrendered for conversion, shall be accompanied
by an instrument of transfer, in form satisfactory to the Company, duly executed
by the registered holder thereof or his duly authorized attorney; and provided
further, however, that the Company shall not be required to pay any tax which
may be payable in respect of any transfer involved in the issuance and delivery
of any such certificates in a name other than that of the holder of the
converted Note, and the Company shall not be required to issue or deliver such
certificates unless or until the Person or Persons requesting the issuance
thereof shall have paid to the Company the amount of such tax or shall have
established to the satisfaction of the Company that such tax has been paid or is
not applicable.

Section 5.05. Company to Provide Stock.

      The Company shall at all times reserve and keep available, free from
preemptive rights, out of its authorized but unissued Common Stock, solely for
the purpose of issuance upon conversion of Notes as herein provided, a
sufficient number of shares of Common Stock to permit the conversion of all
outstanding Notes for shares of Common Stock. All shares of Common Stock which
may be issued upon conversion of the Notes shall be duly authorized, validly
issued, fully paid and nonassessable when so issued. Shares of Common Stock
issuable upon conversion of a Restricted Note shall bear such restrictive
legends as the Company shall provide in accordance with applicable law. If
shares of Common Stock are to be issued upon conversion of a Restricted Note and
they are to be registered in a name other than that of the holder of such
Restricted Note, then the Person in whose name such shares of Common Stock are
to be registered must deliver to the Trustee a certificate satisfactory to the
Company and signed by such Person as to compliance with the restrictions on
transfer contained in such restrictive legends.

Section 5.06. Adjustment of Conversion Price.

      The Conversion Price shall be subject to adjustment from time to time as
follows:

            (a) In case the Company shall (1) pay a dividend in shares of Common
      Stock to holders of Common Stock, (2) make a distribution in shares of
      Common Stock to holders of Common Stock, (3) subdivide its outstanding
      shares of Common Stock into a greater number of shares of Common Stock or
      (4) combine its outstanding shares of Common Stock into a smaller number
      of shares of Common Stock, the Conversion Price in effect immediately
      prior to such action shall be adjusted so that the holder of any Note
      thereafter surrendered for conversion shall be entitled to receive the
      number of shares of Common Stock which he would have owned immediately
      following such action had such Notes been converted immediately prior
      thereto. Any adjustment made pursuant to this subsection (a) shall become
      effective immediately after the 


                                       33
<PAGE>   34

      record date in the case of a dividend or distribution and shall become
      effective immediately after the effective date in the case of a
      subdivision or combination.

            (b) In case the Company shall issue rights or warrants to
      substantially all holders of Common Stock entitling them (for a period
      commencing no earlier than the record date for the determination of
      holders of Common Stock entitled to receive such rights or warrants and
      expiring not more than 45 days after such record date) to subscribe for or
      purchase shares of Common Stock (or securities convertible into Common
      Stock) at a price per share less than the current market price (as
      determined pursuant to subsection (f) below) of the Common Stock on such
      record date, the Conversion Price shall be adjusted so that the same shall
      equal the price determined by multiplying the Conversion Price in effect
      immediately prior to such record date by a fraction of which the numerator
      shall be the number of shares of Common Stock outstanding on such record
      date, plus the number of shares of Common Stock which the aggregate
      offering price of the offered shares of Common Stock (or the aggregate
      conversion price of the convertible securities so offered) would purchase
      at such current market price, and of which the denominator shall be the
      number of shares of Common Stock outstanding on such record date plus the
      number of additional shares of Common Stock offered (or into which the
      convertible securities so offered are convertible). Such adjustments shall
      become effective immediately after such record date.

            (c) In case the Company shall distribute to all holders of Common
      Stock shares of any class of stock other than Common Stock, evidences of
      indebtedness or other assets (other than cash dividends out of current or
      retained earnings), or shall distribute to substantially all holders of
      Common Stock rights or warrants to subscribe for securities (other than
      those referred to in subsection (b) above), then in each such case the
      Conversion Price shall be adjusted so that the same shall equal the price
      determined by multiplying the Conversion Price in effect immediately prior
      to the date of such distribution by a fraction of which the numerator
      shall be the current market price (determined as provided in subsection
      (f) below) of the Common Stock on the record date mentioned below less the
      then fair market value (as determined by the Board of Directors, whose
      determination shall be conclusive evidence of such fair market value and
      described in a Board Resolution) of the portion of the assets so
      distributed or of such subscription rights or warrants applicable to one
      share of Common Stock, and of which the denominator shall be such current
      market price of the Common Stock. Such adjustment shall become effective
      immediately after the record date for the determination of the holders of
      Common Stock entitled to receive such distribution. Notwithstanding the
      foregoing, in the event that the Company shall distribute rights or
      warrants (other than those referred to in subsection (b) above) ("Rights")
      pro rata to holders of Common Stock, the Company may, in lieu of making
      any adjustment pursuant to this Section 5.06, make proper provision so
      that each holder of a Note who converts such Note (or any portion thereof)
      after the record date for such distribution and prior to the expiration or
      redemption of the Rights shall be entitled to receive upon such
      conversion, in addition to the shares of Common Stock issuable upon such
      conversion (the "Conversion Shares"), a number of Rights to be determined
      as follows: (i) if such conversion occurs on or prior to the date for the
      distribution to the holders of Rights of separate certificates evidencing
      such Rights (the "Distribution Date"), the same number of Rights to which
      a holder of a number of shares of Common Stock equal to the number of
      Conversion Shares is entitled at the time of such conversion in accordance
      with the terms and provisions of and applicable to the Rights; and (ii) if
      such conversion occurs after the Distribution Date, the same number of
      Rights to which a holder of the number of shares of Common Stock into
      which the principal amount of the Note so 


                                       34
<PAGE>   35

      converted was convertible immediately prior to the Distribution Date would
      have been entitled on the Distribution Date in accordance with the terms
      and provisions of and applicable to the Rights.

            (d) In case the Company shall, by dividend or otherwise, at any time
      distribute to all holders of its Common Stock cash (including any
      distributions of cash out of current or retained earnings of the Company
      but excluding any cash that is distributed as part of a distribution
      requiring a Conversion Price adjustment pursuant to paragraph (c) of this
      Section 5.06) in an aggregate amount that, together with the sum of (x)
      the aggregate amount of any other distributions to all holders of its
      Common Stock made in cash plus (y) all Excess Payments, in each case made
      within the 12 months preceding the date fixed for determining the
      stockholders entitled to such distribution (the "Distribution Record
      Date") and in respect of which no Conversion Price adjustment pursuant to
      paragraphs (c) or (e) of this Section 5.06 or this paragraph (d) has been
      made, exceeds 10% of the product of the current market price per share
      (determined as provided in paragraph (f) of this Section 5.06) of the
      Common Stock on the Distribution Record Date times the number of shares of
      Common Stock outstanding on the Distribution Record Date (excluding shares
      held in the treasury of the Company), the Conversion Price shall be
      reduced so that the same shall equal the price determined by multiplying
      such Conversion Price in effect immediately prior to the effectiveness of
      the Conversion Price reduction contemplated by this paragraph (d) by a
      fraction of which the numerator shall be the current market price per
      share (determined as provided in paragraph (f) of this Section 5.06) of
      the Common Stock on the Distribution Record Date less the amount of such
      cash and other consideration (including any Excess Payments) so
      distributed applicable to one share (based on the pro rata portion of the
      aggregate amount of such cash and other consideration (including any
      Excess Payments), divided by the shares of Common Stock outstanding on the
      Distribution Record Date) of Common Stock and the denominator shall be
      such current market price per share (determined as provided in paragraph
      (f) of this Section 5.06) of the Common Stock on the Distribution Record
      Date, such reduction to become effective immediately prior to the opening
      of business on the day following the Distribution Record Date.

            (e) In case a tender offer or other negotiated transaction made by
      the Company or any Subsidiary for all or any portion of the Common Stock
      shall be consummated, if an Excess Payment is made in respect of such
      tender offer or other negotiated transaction and the amount of such Excess
      Payment, together with the sum of (x) the aggregate amount of all Excess
      Payments plus (y) the aggregate amount of all distributions to all holders
      of the Common Stock made in cash (specifically including distributions of
      cash out of retained earnings), in each case made within the 12 months
      preceding the date of payment of such current negotiated transaction
      consideration or expiration of such current tender offer, as the case may
      be (the "Purchase Date"), and as to which no adjustment pursuant to
      paragraph (c) or paragraph (d) of this Section 5.06 or this paragraph (e)
      has been made, exceeds 10% of the product of the current market price per
      share (determined as provided in paragraph (f) of this Section 5.06) of
      the Common Stock on the Purchase Date times the number of shares of Common
      Stock outstanding (including any tendered shares but excluding any shares
      held in the treasury of the Company) on the Purchase Date, the Conversion
      Price shall be reduced so that the same shall equal the price determined
      by multiplying such Conversion Price in effect immediately prior to the
      effectiveness of the Conversion Price reduction contemplated by this
      paragraph (e) by a fraction of which the numerator shall be the current
      market price per share (determined as provided in paragraph (f) of this
      Section 5.06) of the Common Stock on the Purchase Date less the amount of
      such Excess Payments and such cash distributions, if any, applicable to
      one share (based on the pro rata 


                                       35
<PAGE>   36

      portion of the aggregate amount of such Excess Payments and such cash
      distributions, divided by the shares of Common Stock outstanding on the
      Purchase Date) of Common Stock and the denominator shall be such current
      market price per share (determined as provided in paragraph (f) of this
      Section 5.06) of the Common Stock on the Purchase Date, such reduction to
      become effective immediately prior to the opening of business on the day
      following the Purchase Date.

            (f) The current market price per share of Common Stock on any date
      shall be deemed to be the average of the Daily Market Prices for the
      shorter of (i) thirty consecutive business days ending on the last full
      trading day on the exchange or market referred to in determining such
      Daily Market Prices prior to the time of determination or (ii) the period
      commencing on the date next succeeding the first public announcement of
      the issuance of such rights or such warrants or such other distribution or
      such negotiated transaction through such last full trading day on the
      exchange or market referred to in determining such Daily Market Prices
      prior to the time of determination.

            (g) In any case in which this Section 5.06 shall require that an
      adjustment be made immediately following a record date, the Company may
      elect to defer (but only until five Business Days following the filing by
      the Company with the Trustee of the certificate described in Section 5.10
      hereof) issuing to the holder of any Note converted after such record date
      the shares of Common Stock and other Capital Stock of the Company issuable
      upon such conversion over and above the shares of Common Stock and other
      Capital Stock of the Company issuable upon such conversion only on the
      basis of the Conversion Price prior to adjustment; and, in lieu of the
      shares the issuance of which is so deferred, the Company shall issue or
      cause its transfer agents to issue due bills or other appropriate evidence
      of the right to receive such shares.

Section 5.07. No Adjustment.

      No adjustment in the Conversion Price shall be required until cumulative
adjustments amount to 1% or more of the Conversion Price as last adjusted;
provided, however, that any adjustments which by reason of this Section 5.07 are
not required to be made shall be carried forward and taken into account in any
subsequent adjustment. All calculations under this Article V shall be made to
the nearest cent or to the nearest one-hundredth of a share, as the case may be.
No adjustment need be made for rights to purchase Common Stock pursuant to a
Company plan for reinvestment of dividends or interest. No adjustment need be
made for a change in the par value or no par value of the Common Stock.

Section 5.08. Other Adjustments.

      (a) In the event that, as a result of an adjustment made pursuant to
Section 5.06 hereof, the holder of any Note thereafter surrendered for
conversion shall become entitled to receive any shares of Capital Stock of the
Company other than shares of its Common Stock, thereafter the Conversion Price
of such other shares so receivable upon conversion of any Note shall be subject
to adjustment from time to time in a manner and on terms as nearly equivalent as
practicable to the provisions with respect to Common Stock contained in this
Article V.

      (b) In the event that shares of Common Stock are not delivered after the
expiration of any of the rights or warrants referred to in Section 5.06(b) and
Section 5.06(c) hereof, the Conversion Price shall be readjusted to the
Conversion Price which would otherwise be in effect had the adjustment made upon
the issuance of such rights or warrants been made on the basis of delivery of
only the number of shares of 


                                       36
<PAGE>   37

Common Stock actually delivered.

Section 5.09. Adjustments for Tax Purposes.

      The Company may make such reductions in the Conversion Price, in addition
to those required by Section 5.06 hereof, as it determines to be advisable in
order that any stock dividend, subdivision of shares, distribution or rights to
purchase stock or securities or distribution of securities convertible into or
exchangeable for stock made by the Company to its stockholders will not be
taxable to the recipients thereof.

Section 5.10. Notice of Adjustment.

      Whenever the Conversion Price is adjusted, the Company shall promptly mail
to Holders at the addresses appearing on the Registrar's books a notice of the
adjustment and file with the Trustee an Officers' Certificate briefly stating
the facts requiring the adjustment and the manner of computing it. The
certificate shall be conclusive evidence of the correctness of such adjustment.

Section 5.11. Notice of Certain Transactions.

      In the event that:

      (1) the Company takes any action which would require an adjustment in the
Conversion Price;

      (2) the Company takes any action that would require a supplemental
indenture pursuant to Section 5.12; or

      (3) there is a dissolution or liquidation of the Company;

a Holder of a Note may wish to convert such Note into shares of Common Stock
prior to the record date for or the effective date of the transaction so that he
may receive the rights, warrants, securities or assets which a holder of shares
of Common Stock on that date may receive. Therefore, the Company shall mail to
Holders at the addresses appearing on the Registrar's books and the Trustee a
notice stating the proposed record or effective date, as the case may be. The
Company shall mail the notice at least 15 days before such date; however,
failure to mail such notice or any defect therein shall not affect the validity
of any transaction referred to in clause (1), (2) or (3) of this Section 5.11.

Section 5.12.  Effect of Reclassifications, Consolidations, Mergers or Sales
on Conversion Privilege.

      If any of the following shall occur, namely: (i) any reclassification or
change of outstanding shares of Common Stock issuable upon conversion of Notes
(other than a change in par value, or from par value to no par value, or from no
par value to par value, or as a result of a subdivision or combination), (ii)
any consolidation or merger to which the Company is a party other than a merger
in which the Company is the continuing corporation and which does not result in
any reclassification of, or change (other than a change in name, or par value,
or from par value to no par value, or from no par value to par value or as a
result of a subdivision or combination) in, outstanding shares of Common Stock
or (iii) any sale or conveyance of all or substantially all of the property or
business of the Company as an entirety, then the Company, or such successor or
purchasing corporation, as the case may be, shall, as a condition precedent to
such reclassification, change, consolidation, merger, sale or conveyance,
execute and deliver to the Trustee a supplemental indenture in form satisfactory
to the Trustee providing that the 


                                       37
<PAGE>   38

holder of each Note then outstanding shall have the right to convert such Note
into the kind and amount of shares of stock and other securities and property
(including cash) receivable upon such reclassification, change, consolidation,
merger, sale or conveyance by a holder of the number of shares of Common Stock
deliverable upon conversion of such Note immediately prior to such
reclassification, change, consolidation, merger, sale or conveyance. Such
supplemental indenture shall provide for adjustments of the Conversion Price
which shall be as nearly equivalent as may be practicable to the adjustments of
the Conversion Price provided for in this Article V. The foregoing, however,
shall not in any way affect the right a holder of a Note may otherwise have,
pursuant to clause (ii) of the last sentence of subsection (c) of Section 5.06
hereof, to receive Rights upon conversion of a Note. If, in the case of any such
consolidation, merger, sale or conveyance, the stock or other securities and
property (including cash) receivable thereupon by a holder of Common Stock
includes shares of stock or other securities and property of a corporation other
than the successor or purchasing corporation, as the case may be, in such
consolidation, merger, sale or conveyance, then such supplemental indenture
shall also be executed by such other corporation and shall contain such
additional provisions to protect the interests of the holders of the Notes as
the Board of Directors of the Company shall reasonably consider necessary by
reason of the foregoing. The provision of this Section 5.12 shall similarly
apply to successive consolidations, mergers, sales or conveyances.

      In the event the Company shall execute a supplemental indenture pursuant
to this Section 5.12, the Company shall promptly file with the Trustee an
Officers' Certificate briefly stating the reasons therefor, the kind or amount
of shares of stock or securities or property (including cash) receivable by
holders of the Notes upon the conversion of their Notes after any such
reclassification, change, consolidation, merger, sale or conveyance and any
adjustment to be made with respect thereto.

Section 5.13. Trustee's Disclaimer.

      The Trustee has no duty to determine when an adjustment under this Article
V should be made, how it should be made or what such adjustment should be, but
may accept as conclusive evidence of the correctness of any such adjustment, and
shall be protected in relying upon the Officers' Certificate with respect
thereto which the Company is obligated to file with the Trustee pursuant to
Section 5.10 hereof. The Trustee makes no representation as to the validity or
value of any securities or assets issued upon conversion of Notes, and the
Trustee shall not be responsible for the Company's failure to comply with any
provisions of this Article V.

      The Trustee shall not be under any responsibility to determine the
correctness of any provisions contained in any supplemental indenture executed
pursuant to Section 5.12, but may accept as conclusive evidence of the
correctness thereof, and shall be protected in relying upon, the Officers'
Certificate with respect thereto which the Company is obligated to file with the
Trustee pursuant to Section 5.12 hereof.

                                   ARTICLE VI.
                                  Subordination

Section 6.01.  Agreement to Subordinate and Ranking.

      The Company, for itself and its successors, and each holder, by his
acceptance of Notes, agree that the payment of the principal of or interest or
Liquidated Damages, if any, on or any other amounts due on the Notes is
subordinated in right of payment, to the extent and in the manner stated in this
Article VI, to the prior payment in full of all existing and future Senior Debt.
The Notes shall rank pari passu 


                                       38
<PAGE>   39

with, and shall not be senior in right of payment to, the Existing Convertible
Notes or such other Indebtedness of the Company whether outstanding on the date
of this Indenture or hereafter created, incurred, issued or guaranteed by the
Company, where the instrument creating or evidencing such Indebtedness expressly
provides that such Indebtedness ranks pari passu with the Notes and the Existing
Convertible Notes.

Section 6.02.  No Payment in Notes if Senior Debt in Default.

      Anything in this Indenture to the contrary notwithstanding, no payment on
account of principal of or redemption of, interest or Liquidated Damages, if
any, on or other amounts due on the Notes, and no redemption, purchase, or other
acquisition of the Notes, shall be made by or on behalf of the Company (i)
unless full payment of amounts then due for principal and interest and of all
other amounts then due on all Senior Debt has been made or duly provided for
pursuant to the terms of the instrument governing such Senior Debt, (ii) if, at
the time of such payment, redemption, purchase or other acquisition, or
immediately after giving effect thereto, there shall exist under any Senior
Debt, or any agreement pursuant to which any Senior Debt is issued, any default,
which default shall not have been cured or waived and which default shall have
resulted in the full amount of such Senior Debt being declared due and payable
or (iii) if, at the time of such payment, redemption, purchase or other
acquisition, the Trustee shall have received written notice from any of the
holders of Senior Debt or such holder's representative (a "Payment Blockage
Notice") that there exists under such Senior Debt, or any agreement pursuant to
which such Senior Debt is issued, any default, which default shall not have been
cured or waived, permitting the holders thereof to declare any amounts of such
Senior Debt due and payable, but only for the period (the "Payment Blockage
Period") commencing on the date of receipt of the Payment Blockage Notice and
ending (unless earlier terminated by notice given to the Trustee by the holders
of such Senior Debt) on the earlier of (a) the date on which such event of
default shall have been cured or waived or (b)180 days from the receipt of the
Payment Blockage Notice. Upon termination of the Payment Blockage Period,
payments on account of principal of or interest or Liquidated Damages, if any,
on the Notes (other than, subject to Section 6.03 hereof, amounts due and
payable by reason of the acceleration of the maturity of the Notes) and
redemptions, purchases or other acquisitions may be made by or on behalf of the
Company. Notwithstanding anything herein to the contrary, (a) only one Payment
Blockage Notice may be given during any period of 360 consecutive days with
respect to the same event of default or any other events of default on the same
issue of Senior Debt existing and known to the Person giving such notice at the
time of such notice unless such event of default or such other events of default
have been cured or waived for a period of not less than 90 consecutive days and
(b) no new Payment Blockage Period may be commenced by the holder or holders of
the same issue of Senior Debt or their representative or representatives during
any period of 360 consecutive days unless all events of default which were the
object of the immediately preceding Payment Blockage Notice, and any other event
of default on the same issue of Senior Debt existing and known to the Person
giving such notice at the time of such notice, have been cured or waived.

      In the event that, notwithstanding the provisions of this Section 6.02,
payments are made by or on behalf of the Company in contravention of the
provisions of this Section 6.02, such payments shall be held by the Trustee, any
Paying Agent or the holders, as applicable, in trust for the benefit of, and
shall be paid over to and delivered to, the holders of Senior Debt or their
representative or the trustee under the indenture or other agreement (if any),
pursuant to which any instruments evidencing any Senior Debt may have been
issued for application to the payment of all Senior Debt ratably according to
the aggregate amounts remaining unpaid to the extent necessary to pay all Senior
Debt in full in accordance with the terms of such Senior Debt, after giving
effect to any concurrent payment or distribution to or for the 


                                       39
<PAGE>   40

holders of Senior Debt.

      The Company shall give prompt written notice to the Trustee and any Paying
Agent of any default or event of default under any Senior Debt or under any
agreement pursuant to which any Senior Debt may have been issued.

Section 6.03.  Distribution in Acceleration of Notes; Dissolution and
               Reorganization; Subrogation of Notes.

      (a) If the Notes are declared due and payable because of the occurrence of
an Event of Default, the Company or the Trustee shall give prompt written notice
to the holders of all Senior Debt or to the trustee(s) for such Senior Debt of
such acceleration. The Company may not pay the principal of or interest or
Liquidated Damages, if any, on or any other amounts due on the Notes until five
days after such holders or trustee(s) of Senior Debt receive such notice and,
thereafter, the Company may pay the principal of or interest or Liquidated
Damages, if any, on or any other amounts due on the Notes only if the provisions
of this Article VI permit such payment.

      (b) Upon (i) any acceleration of the principal amount due on the Notes
because of an Event of Default or (ii) any distribution of assets of the Company
upon any dissolution, winding up, liquidation or reorganization of the Company
(whether in bankruptcy, insolvency or receivership proceedings or upon an
assignment for the benefit of creditors or any other dissolution, winding up,
liquidation or reorganization of the Company):

            (1) the holders of all Senior Debt shall first be entitled to
      receive payment in full of the principal thereof, the interest thereon and
      any other amounts due thereon before the holders are entitled to receive
      payment on account of the principal of or interest or Liquidated Damages,
      if any, on or any other amounts due on the Notes;

            (2) any payment or distribution of assets of the Company of any kind
      or character, whether in cash, property or securities (other than
      securities of the Company as reorganized or readjusted or securities of
      the Company or any other corporation provided for by a plan of
      reorganization or readjustment the payment of which is subordinate, at
      least to the extent provided in this Article VI with respect to the Notes,
      to the payment in full without diminution or modification by such plan of
      all Senior Debt), to which the holders or the Trustee would be entitled
      except for the provisions of this Article VI, shall be paid by the
      liquidating trustee or agent or other Person making such a payment or
      distribution, directly to the holders of Senior Debt (or their
      representatives(s) or trustee(s) acting on their behalf), ratably
      according to the aggregate amounts remaining unpaid on account of the
      principal of or interest on and other amounts due on the Senior Debt held
      or represented by each, to the extent necessary to make payment in full of
      all Senior Debt remaining unpaid, after giving effect to any concurrent
      payment or distribution to the holders of such Senior Debt; and

            (3) in the event that, notwithstanding the foregoing, any payment or
      distribution of assets of the Company of any kind or character, whether in
      cash, property or securities (other than securities of the Company as
      reorganized or readjusted, or securities of the Company or any other
      corporation provided for by a plan of reorganization or readjustment the
      payment of which is subordinate, at least to the extent provided in this
      Article VI with respect to the Notes, to the payment in full without
      diminution or modification by such plan of Senior Debt), shall be 


                                       40
<PAGE>   41

      received by the Trustee or the holders before all Senior Debt is paid in
      full, such payment or distribution shall be held in trust for the benefit
      of, and be paid over to upon request by a holder of the Senior Debt, the
      holders of the Senior Debt remaining unpaid (or their representatives) or
      trustee(s) acting on their behalf, ratably as aforesaid, for application
      to the payment of such Senior Debt until all such Senior Debt shall have
      been paid in full, after giving effect to any concurrent payment or
      distribution to the holders of such Senior Debt.

      Subject to the payment in full of all Senior Debt, the holders shall be
subrogated to the rights of the holders of Senior Debt to receive payments or
distributions of cash, property or securities of the Company applicable to the
Senior Debt until the principal of and interest and Liquidated Damages, if any,
on the Notes shall be paid in full and, for purposes of such subrogation, no
such payments or distributions to the holders of Senior Debt of cash, property
or securities which otherwise would have been payable or distributable to
holders shall, as between the Company, its creditors other than the holders of
Senior Debt, and the holders, be deemed to be a payment by the Company to or on
account of the Senior Debt, it being understood that the provisions of this
Article VI are and are intended solely for the purpose of defining the relative
rights of the Holders, on the one hand, and the holders of Senior Debt, on the
other hand.

      Nothing contained in this Article VI or elsewhere in this Indenture or in
the Notes is intended to or shall (i) impair, as between the Company and its
creditors other than the holders of Senior Debt, the obligation of the Company,
which is absolute and unconditional, to pay to the holders the principal of and
interest and Liquidated Damages, if any, on the Notes as and when the same shall
become due and payable in accordance with the terms of the Notes or is intended
to or (ii) affect the relative rights of the holders and creditors of the
Company other than holders of Senior Debt or, as between the Company and the
Trustee, the obligations of the Company to the Trustee, or (iii) prevent the
Trustee or the holders from exercising all remedies otherwise permitted by
applicable law upon default under this Indenture, subject to the rights, if any,
under this Article VI of the holders of Senior Debt in respect of cash, property
and securities of the Company received upon the exercise of any such remedy.

      Upon distribution of assets of the Company referred to in this Article VI,
the Trustee, subject to the provisions of Section 9.01 hereof, and the holders
shall be entitled to rely upon a certificate of the liquidating trustee or agent
or other Person making any distribution to the Trustee or to the holders for the
purpose of ascertaining the Persons entitled to participate in such
distribution, the holders of the Senior Debt and other indebtedness of the
Company, the amount thereof or payable thereon, the amount or amounts paid or
distributed thereon and all other facts pertinent thereto or to this Article VI.
The Trustee, however, shall not be deemed to owe any fiduciary duty to the
holders of Senior Debt. Nothing contained in this Article VI or elsewhere in
this Indenture, or in any of the Notes, shall prevent the good faith application
by the Trustee of any moneys which were deposited with it hereunder, prior to
its receipt of written notice of facts which would prohibit such application,
for the purpose of the payment of or on account of the principal of or interest
or Liquidated Damages, if any, on, the Notes unless, prior to the date on which
such application is made by the Trustee, the Trustee shall be charged with
notice under Section 6.03(d) hereof of the facts which would prohibit the making
of such application.

      (c) The provisions of this Article VI shall not be applicable to any cash,
properties or securities received by the Trustee or by any holder when received
as a holder of Senior Debt and nothing in Section 9.11 hereof or elsewhere in
this Indenture shall deprive the Trustee or such holder of any of its rights as
such holder.

      (d) The Company shall give prompt written notice to the Trustee of any
fact known to the 


                                       41
<PAGE>   42

Company which would prohibit the making of any payment of money to or by the
Trustee in respect of the Notes pursuant to the provisions of this Article VI.
The Trustee, subject to the provisions of Section 9.01 hereof, shall be entitled
to assume that no such fact exists unless the Company or any holder of Senior
Debt or any trustee therefor has given such notice to the Trustee.
Notwithstanding the provisions of this Article VI or any other provisions of
this Indenture, the Trustee shall not be charged with knowledge of the existence
of any fact which would prohibit the making of any payment of monies to or by
the Trustee in respect of the Notes pursuant to the provisions in this Article
VI, unless, and until three Business Days after, the Trustee shall have received
written notice thereof from the Company or any holder or holders of Senior Debt
or from any trustee therefor; and, prior to the receipt of any such written
notice, the Trustee, subject to the provisions of Section 9.01 hereof, shall be
entitled in all respects conclusively to assume that no such facts exist;
provided that if on a date not less than three Business Days immediately
preceding the date upon which by the terms hereof any such monies may become
payable for any purpose (including, without limitation, the principal of or
interest or Liquidated Damages, if any, on any Note), the Trustee shall not have
received with respect to such monies the notice provided for in this Section
6.03(d), than anything herein contained to the contrary notwithstanding, the
Trustee shall have full power and authority to receive such monies and to apply
the same to the purpose for which they were received, and shall not be affected
by any notice to the contrary which may be received by it on or after such prior
date.

      The Trustee shall be entitled to rely on the delivery to it of a written
notice by a Person representing himself to be a holder of Senior Debt (or a
trustee on behalf of such holder) to establish that such notice has been given
by a holder of Senior Debt (or a trustee on behalf of any such holder or
holders). In the event that the Trustee determines in good faith that further
evidence is required with respect to the right of any Person as a holder of
Senior Debt to participate in any payment or distribution pursuant to this
Article VI, the Trustee may request such Person to furnish evidence to the
reasonable satisfaction of the Trustee as to the amount of Senior Debt held by
such Person, the extent to which such Person is entitled to participate in such
payment or distribution and any other facts pertinent to the rights of such
Person under this Article VI, and, if such evidence is not furnished, the
Trustee may defer any payment to such Person pending judicial determination as
to the right of such Person to receive such payment; nor shall the Trustee be
charged with knowledge of the curing or waiving of any default of the character
specified in Section 6.02 hereof or that any event or any condition preventing
any payment in respect of the Notes shall have ceased to exist, unless and until
the Trustee shall have received an Officers' Certificate to such effect.

      (e) The provisions of this Section 6.03 applicable to the Trustee shall
also apply to any Paying Agent for the Company.

Section 6.04.  Reliance by Senior Debt in Subordination Provisions.

      Each holder of any Note by his acceptance thereof acknowledges and agrees
that the foregoing subordination provisions are, and are intended to be, an
inducement and a consideration for each holder of any Senior Debt, whether such
Senior Debt was created or acquired before or after the issuance of the Notes,
to acquire and continue to hold, or to continue to hold, such Senior Debt, and
such holder of Senior Debt shall be deemed conclusively to have relied on such
subordination provisions in acquiring and continuing to hold, or in continuing
to hold, such Senior Debt. Notice of any default in the payment of any Senior
Debt, except as expressly stated in this Article VI, and notice of acceptance of
the provisions hereof are hereby expressly waived. Except as otherwise expressly
provided herein, no waiver, forbearance or release by any holder of Senior Debt
under such Senior Debt or under this 


                                       42
<PAGE>   43

Article VI shall constitute a release of any of the obligations or liabilities
of the Trustee or holders of the Notes provided in this Article VI.

Section 6.05.  No Waiver of Subordination Provisions.

      Except as otherwise expressly provided herein, no right of any present or
future holder of any Senior Debt to enforce subordination as herein provided
shall at any time in any way be prejudiced or impaired by any act or failure to
act on the part of the Company or by any act or failure to act, in good faith,
by any such holder, or by any noncompliance by the Company with the terms,
provisions and covenants of this Indenture, regardless of any knowledge thereof
any such holder may have or be otherwise charged with.

      Without in any way limiting the generality of the foregoing paragraph, the
holders of Senior Debt may, at any time and from time to time, without the
consent of, or notice to, the Trustee or the holders of the Notes, without
incurring responsibility to the holders of the Notes and without impairing or
releasing the subordination provided in this Article VI or the obligations
hereunder of the holders of the Notes to the holders of Senior Debt, do any one
or more of the following: (i) change the manner, place or terms of payment of,
or renew or alter, Senior Debt, or otherwise amend or supplement in any manner
Senior Debt or any instrument evidencing the same or any agreement under which
Senior Debt is outstanding; (ii) sell, exchange, release or otherwise dispose of
any property pledged, mortgaged or otherwise securing Senior Debt; (iii) release
any Person liable in any manner for the collection of Senior Debt; and (iv)
exercise or refrain from exercising any rights against the Company or any other
Person.

Section 6.06.  Trustee's Relation to Senior Debt.

      The Trustee in its individual capacity shall be entitled to all the rights
set forth in this Article VI in respect of any Senior Debt at any time held by
it, to the same extent as any holder of Senior Debt, and nothing in Section 9.11
hereof or elsewhere in this Indenture shall deprive the Trustee of any of its
rights as such holder.

      With respect to the holders of Senior Debt, the Trustee undertakes to
perform or to observe only such of its covenants and obligation, as are
specifically set forth in this Article VI, and no implied covenants or
obligations with respect to the holders of Senior Debt shall be read into this
Indenture against the Trustee. The Trustee shall not owe any fiduciary duty to
the holders of Senior Debt but shall have only such obligations to such holders
as are expressly set forth in this Article VI.

      Each holder of a Note by his acceptance thereof authorizes and directs the
Trustee on his behalf to take such action as may be necessary or appropriate to
effectuate the subordination provided in this Article VI and appoints the
Trustee his attorney-in-fact for any and all such purposes, including, in the
event of any dissolution, winding up or liquidation or reorganization under any
applicable bankruptcy law of the Company (whether in bankruptcy, insolvency or
receivership proceedings or otherwise), the timely filing of a claim for the
unpaid balance of such holder's Notes in the form required in such proceedings
and the causing of such claim to be approved. If the Trustee does not file a
claim or proof of debt in the form required in such proceedings prior to 30 days
before the expiration of the time to file such claims or proofs, then any holder
or holders of Senior Debt or their representative or representatives shall have
the right to demand, sue for, collect, receive and receipt for the payments and
distributions in respect of the Notes which are required to be paid or delivered
to the holders of Senior Debt as provided in this Article VI and to file and
prove all claims therefore and to take all such other action in the name of the
holders or 


                                       43
<PAGE>   44

otherwise, as such holders of Senior Debt or representative thereof may
determine to be necessary or appropriate for the enforcement of the provisions
of this Article VI.

Section 6.07.  Other Provisions Subject Hereto.

      Expect as expressly stated in this Article VI, notwithstanding anything
contained in this Indenture to the contrary, all the provisions of this
Indenture and the Notes are subject to the provisions of this Article VI.
However, nothing in this Article VI shall apply to or adversely affect the
claims of, or payment, to, the Trustee pursuant to Section 9.07 hereof.
Notwithstanding the foregoing, the failure to make a payment on account of
principal of or interest or Liquidated Damages, if any, on the Notes by reason
of any provision of this Article VI shall not be construed as preventing the
occurrence of an Event of Default under Section 8.01 hereof.

                                  ARTICLE VII.
                                   Successors

Section 7.01.  Merger, Consolidation or Sale of Assets.

      The Company may not consolidate or merge with or into (whether or not the
Company is the surviving corporation), or sell, assign, transfer, lease, convey
or otherwise dispose of all or substantially all of its properties or assets in
one or more related transactions to, another corporation, Person or entity
unless:

            (a) the Company is the surviving corporation or the entity or the
      Person formed by or surviving any such consolidation or merger (if other
      than the Company) or to which such sale, assignment, transfer, lease,
      conveyance or other disposition shall have been made is a corporation
      organized or existing under the laws of the United Kingdom, the
      Netherlands, the Netherlands Antilles, Bermuda or the Cayman Islands or of
      the United States, any state thereof or the District of Columbia;

            (b) the entity or Person formed by or surviving any such
      consolidation or merger (if other than the Company) or the entity or
      Person to which such sale, assignment, transfer, lease, conveyance or
      other disposition will have been made assumes all the Obligations
      (including the due and punctual payment of Additional Amounts if the
      surviving corporation is a corporation organized or existing under the
      laws of the United Kingdom, the Netherlands, the Netherlands Antilles,
      Bermuda or the Cayman Islands) of the Company, pursuant to a supplemental
      indenture in a form reasonably satisfactory to the Trustee, under the
      Notes and this Indenture;

            (c) immediately after such transaction no Default or Event of
      Default exists;

            (d) the Company or any entity or Person formed by or surviving any
      such consolidation or merger, or to which such sale, assignment, transfer,
      lease, conveyance or other disposition will have been made will have a
      ratio of Indebtedness to Annualized Pro Forma EBITDA equal to or less than
      the ratio of Indebtedness to Annualized Pro Forma EBITDA of the Company
      immediately preceding the transaction; provided, however, that if the
      ratio of Indebtedness to Annualized Pro Forma EBITDA of the Company
      immediately preceding such transaction is 6:1 or less, then the ratio of
      Indebtedness to Annualized Pro Forma EBITDA of the Company may be 0.5
      greater than such ratio immediately preceding such transaction; and


                                       44
<PAGE>   45

            (e) such transaction would not result in the loss of any material
      authorization or Material License of the Company or its Subsidiaries.

Section 7.02.  Successor Corporation Substituted.

      Upon any consolidation or merger, or any sale, assignment, transfer,
lease, conveyance or other disposition of all or substantially all of the assets
of the Company in accordance with Section 7.01 hereof, the successor corporation
formed by such consolidation or into or with which the Company is merged or to
which such sale, assignment, transfer, lease, conveyance or other disposition is
made shall succeed to, and be substituted for and may exercise every right and
power of, the Company under this Indenture with the same effect as if such
successor Person has been named as the Company herein; provided, however, that
the predecessor Company in the case of a sale, assignment, transfer, lease,
conveyance or other disposition shall not be released from the obligation to pay
the principal of and interest on the Notes.

                                  ARTICLE VIII.
                              Defaults and Remedies

Section 8.01.  Events of Default.

      An "Event of Default" occurs if:

            (a) the Company defaults in the payment of interest or Liquidated
      Damages, if any, (and Additional Amounts, if applicable) on any Note when
      the same becomes due and payable and the Default continues for a period of
      30 days after the date due and payable;

            (b) the Company defaults in the payment of the principal of any Note
      when the same becomes due and payable at maturity, upon redemption or
      otherwise;

            (c) the Company fails to observe or perform any covenant or
      agreement contained in Section 4.07 hereof;

            (d) the Company fails to observe or perform any other covenant or
      agreement contained in this Indenture or the Notes, required by it to be
      performed and the Default continues for a period of 60 days after notice
      from the Trustee to the Company or from the Holders of 25% in aggregate
      principal amount of the then outstanding Notes to the Company and the
      Trustee stating that such notice is a "Notice of Default";

            (e) default under any mortgage, indenture or instrument under which
      there may be issued or by which there may be secured or evidenced any
      Indebtedness for money borrowed by the Company or any Restricted
      Subsidiary (or the payment of which is guaranteed by the Company or any
      Restricted Subsidiary), whether such Indebtedness or guarantee now exists
      or is created after the Issuance Date, which default:

                  (i) is caused by a failure to pay when due principal of or
            interest on such Indebtedness within the grace period provided for
            in such Indebtedness (which failure continues beyond any applicable
            grace period) (a "Payment Default"); or

                  (ii) results in the acceleration of such Indebtedness prior to
            its express


                                       45
<PAGE>   46

maturity

and, in each case, the principal amount of any such Indebtedness, together with
the principal amount of any other such Indebtedness under which there is a
Payment Default or the maturity of which has been so accelerated, aggregates $10
million or more;

            (f) a final judgment or final judgments (other than any judgment as
      to which a reputable insurance company has accepted full liability) for
      the payment of money are entered by a court or courts of competent
      jurisdiction against the Company or any Restricted Subsidiary of the
      Company which remains undischarged for a period (during which execution
      shall not be effectively stayed) of 60 days, provided that the aggregate
      of all such judgments exceeds $5 million;

            (g) the Company or any Material Subsidiary pursuant to or within the
      meaning of any Bankruptcy Law:

                  (i) commences a voluntary case;

                  (ii) consents to the entry of an order for relief against it
            in an involuntary case in which it is the debtor;

                  (iii) consents to the appointment of a Custodian of it or for
            all or substantially all of its property;

                  (iv) makes a general assignment for the benefit of its
            creditors; or

                  (v) generally is unable to pay its debts as the same become
            due;

            (h) a court of competent jurisdiction enters an order or decree
      under any Bankruptcy Law that:

                  (i) is for relief against the Company or any Material
            Subsidiary in an involuntary case;

                  (ii) appoints a Custodian of the Company or any Material
            Subsidiary or for all or substantially all of its property; or

                  (iii) orders the liquidation of the Company or any Material
            Subsidiary, and the order or decree remains unstayed and in effect
            for 60 days; and

            (i) the revocation of a Material License.

The term "Bankruptcy Law" means Title 11, U.S. Code or any similar Federal,
state or foreign law for the relief of debtors or the protection of creditors.
The term "Custodian" means any receiver, trustee, assignee, liquidator or
similar official under any Bankruptcy Law.

Section 8.02.  Acceleration.

      If an Event of Default (other than an Event of Default specified in
clauses (g) and (h) of Section 


                                       46
<PAGE>   47

8.01 hereof) occurs and is continuing, the Trustee by notice to the Company, or
the Holders of at least 25% in principal amount of the then outstanding Notes by
notice to the Company and the Trustee, may declare all the Notes to be due and
payable. Upon such declaration, the principal of, premium, if any, and interest
and Liquidated Damages, if any, on, the Notes shall be due and payable
immediately. If an Event of Default specified in clause (g) or (h) of Section
8.01 hereof occurs, such an amount shall ipso facto become and be immediately
due and payable without any declaration or other act on the part of the Trustee
or any Holder. The Holders of a majority in principal amount of the then
outstanding Notes by notice to the Trustee may rescind an acceleration and its
consequences if the rescission would not conflict with any judgment or decree
and if all existing Events of Default have been cured or waived except
nonpayment of principal or interest that has become due solely because of the
acceleration. In the case of any Event of Default pursuant to the provisions of
Section 8.01 occurring by reason of any willful action (or inaction) taken (or
not taken) by or on behalf of the Company with the intention of avoiding payment
of the premium that the Company would have had to pay if the Company then had
elected to redeem the Notes pursuant to Section 7 of the Notes, an equivalent
premium shall, upon demand of the Holders of at least 25% in principal amount of
the then outstanding Notes delivered to the Company and the Trustee, also become
and be immediately due and payable to the extent permitted by law, anything in
this Indenture or in the Notes contained to the contrary notwithstanding. If an
Event of Default occurs prior to December 15, 2001, by reason of any willful
action (or inaction) taken (or not taken) by or on behalf of the Company with
the intention of avoiding the prohibition on redemption of the Notes prior to
December 15, 2001, pursuant to Section 7 of the Notes, then the premium payable
for purposes of this paragraph for each of the years beginning on December 15 of
the years (December 16, in the case of the year 1998) set forth below shall,
subject to the foregoing demand, be as set forth in the following table
expressed as a percentage of the amount that would otherwise be due pursuant to
this Section 8.02 hereof but for the provisions of this sentence.

<TABLE>
<CAPTION>
             Year                             Percentage
             ----                             ----------
             <S>                              <C>     
             1998                             107.000%
             1999                             106.125%
             2000                             105.250%
</TABLE>

Section 8.03. Other Remedies.

      If an Event of Default occurs and is continuing, the Trustee may pursue
any available remedy to collect the payment of principal or interest on the
Notes or to enforce the performance of any provision of the Notes or this
Indenture.

      The Trustee may maintain a proceeding even if it does not possess any of
the Notes or does not produce any of them in the proceeding. A delay or omission
by the Trustee or any Holder in exercising any right or remedy accruing upon an
Event of Default shall not impair the right or remedy or constitute a waiver of
or acquiescence in the Event of Default. All remedies are cumulative to the
extent permitted by law.

Section 8.04.  Waiver of Past Defaults.

      The Holders of a majority in principal amount of the then outstanding
Notes by notice to the Trustee may waive an existing Default or Event of Default
and its consequences except a continuing Default or Event of Default in the
payment of the principal of or interest on any Note. When a Default or 


                                       47
<PAGE>   48

Event of Default is waived, it is cured and ceases; but no such waiver shall
extend to any subsequent or other Default or impair any right consequent
thereon.

Section 8.05.  Control by Majority.

      The Holders of a majority in principal amount of the then outstanding
Notes may direct the time, method and place of conducting any proceeding for any
remedy available to the Trustee or exercising any trust or power conferred on
it. However, the Trustee may refuse to follow any direction that conflicts with
law or this Indenture, is unduly prejudicial to the rights of other Holders, or
would involve the Trustee in personal liability.

Section 8.06. Limitation in Suits.

      A Holder may pursue a remedy with respect to this Indenture or the Notes
only if:

            (a) the Holder gives to the Trustee notice of a continuing Event of
      Default;

            (b) the Holders of at least 25% in principal amount of the then
      outstanding Notes make a request to the Trustee to pursue the remedy;

            (c) such Holder or Holders offer to the Trustee indemnity
      satisfactory to the Trustee against any loss, liability or expense;

            (d) the Trustee does not comply with the request within 60 days
      after receipt of the request and the offer of indemnity; and

            (e) during such 60-day period the Holders of a majority in principal
      amount of the then outstanding Notes do not give the Trustee a direction
      inconsistent with the request.

      A Holder may not use this Indenture to prejudice the rights of another
Holder or to obtain a preference or priority over another Holder.

Section 8.07. Rights of Holders to Receive Payment.

      Notwithstanding any other provision of this Indenture, the right of any
Holder of a Note to receive payment of principal, Liquidated Damages, if any,
and interest on the Note, on or after the respective due dates expressed in the
Note, or to bring suit for the enforcement of any such payment on or after such
respective dates, shall not be impaired or affected without the consent of the
Holder made pursuant to this Section 8.07.

Section 8.08.  Collection Suit by Trustee.

      If an Event of Default specified in Section 8.01(a) or (b), hereof occurs
and is continuing, the Trustee may recover judgment in its own name and as
trustee of an express trust against the Company for the whole amount of
principal, Liquidated Damages, if any, and interest remaining unpaid on the
Notes and interest on overdue principal, Liquidated Damages, if any, and
interest and such further amount as shall be sufficient to cover the costs and,
to the extent lawful, expenses of collection, including the reasonable
compensation, expenses, disbursements and advances of the Trustee, its agents
and counsel.


                                       48
<PAGE>   49

Section 8.09. Trustee May File Proofs of Claim.

      The Trustee may file such proofs of claim and other papers or documents as
may be necessary or advisable in order to have the claims of the Trustee and the
Holders allowed in any judicial proceedings relative to the Company, its
creditors or its property. Nothing contained herein shall be deemed to authorize
the Trustee to authorize or consent to or accept or adopt on behalf of any
Holder any plan of reorganization, arrangement, adjustment or composition
affecting the Notes or the rights of any Holder thereof, or to authorize the
Trustee to vote in respect of the claim of any Holder in any such proceeding.

Section 8.10. Priorities.

      If the Trustee collects any money pursuant to this Article, it shall pay
out the money in the following order:

      First: to the Trustee for amounts due under Section 9.07 hereof;

      Second: to the holders of Senior Debt to the extent required by Article
VI;

      Third: to Holders for amounts due and unpaid on the Notes for principal,
Liquidated Damages, if any, and interest (and Additional Amounts, if
applicable), ratably, without preference or priority of any kind, according to
the amounts due and payable on the Notes for principal, Liquidated Damages, if
any, and interest, respectively; and

      Fourth: to the Company.

      The Trustee may fix a record date and payment date for any payment to
Holders made pursuant to this Section 8.10.

Section 8.11. Undertaking for Costs.

      In any suit for the enforcement of any right or remedy under this
Indenture or in any suit against the Trustee for any action taken or omitted by
it as a Trustee, a court in its discretion may require the filing by any party
litigant in the suit of an undertaking to pay the costs of the suit, and the
court in its discretion may assess reasonable costs, including reasonable
attorneys' fees, against any party litigant in the suit, having due regard to
the merits and good faith of the claims or defenses made by the party litigant.
This Section 8.11 does not apply to a suit by the Trustee, a suit by a Holder
pursuant to Section 8.07 hereof, or a suit by Holders of more than 10% in
principal amount of the then outstanding Notes.

                                   ARTICLE IX.
                                     Trustee

Section 9.01. Duties of Trustee.

      (a) If an Event of Default has occurred and is continuing, the Trustee
shall exercise such of the rights and powers vested in it by this Indenture, and
use the same degree of care and skill in their exercise, as a prudent man would
exercise or use under the circumstances in the conduct of his own affairs.


                                       49
<PAGE>   50

      (b) Except during the continuance of an Event of Default: (i) the Trustee
need perform only those duties that are specifically set forth in this Indenture
and no others and (ii) in the absence of bad faith on its part, the Trustee may
conclusively rely, as to the truth of the statements and the correctness of the
opinions expressed therein, upon certificates or opinions furnished to the
Trustee and conforming to the requirements of this Indenture. However, the
Trustee shall examine the certificates and opinions to determine whether or not
they conform to the requirements of this Indenture and to confirm the
correctness of all mathematical computations.

      (c) The Trustee may not be relieved from liability for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that: (i) this paragraph does not limit the effect of paragraph (b) of this
Section 9.01; (ii) the Trustee shall not be liable for any error of judgment
made in good faith by a Trust Officer, unless it is proved that the Trustee was
negligent in ascertaining the pertinent facts and (iii) the Trustee shall not be
liable with respect to any action it takes or omits to take in good faith in
accordance with a direction received by it pursuant to Section 8.05 hereof.

      (d) Every provision of this Indenture that in any way relates to the
Trustee is subject to paragraphs (a), (b) and (c) of this Section 9.01.

      (e) The Trustee may refuse to perform any duty or exercise any right or
power unless it receives indemnity satisfactory to it against any loss,
liability or expense.

      (f) The Trustee shall not be liable for interest on any money received by
it except as the Trustee may agree in writing with the Company. Money held in
trust by the Trustee need not be segregated from other funds except to the
extent required by law.

Section 9.02. Rights of Trustee.

      (a) The Trustee may rely on any document believed by it to be genuine and
to have been signed or presented by the proper Person. The Trustee need not
investigate any fact or matter stated in the document.

      (b) Before the Trustee acts or refrains from acting, it may require an
Officers' Certificate or an Opinion of Counsel, or both. The Trustee shall not
be liable for any action it takes or omits to take in good faith in reliance on
such Officers' Certificate or Opinion of Counsel.

      (c) The Trustee may act through agents and shall not be responsible for
the misconduct or negligence of any agent appointed with due care.

      (d) The Trustee shall not be liable for any action it takes or omits to
take in good faith which it believes to be authorized or within its rights or
powers.

      (e) The Trustee shall not be charged with knowledge of any Event of
Default under subsection (c), (d), (e), (f) or (i) (and subsection (a) or (b) if
the Trustee does not act as Paying Agent) of Section 8.01 or of the identity of
any Material Subsidiary referred to in clause (ii) of the definition thereof
unless either (1) a Trust Officer of the Trustee assigned to its Corporate
Trustee Administration Department shall have actual knowledge thereof, or (2)
the Trustee shall have received notice thereof in accordance with Section 12.02
hereof from the Company or any Holder.

Section 9.03. Individual Rights of Trustee.


                                       50
<PAGE>   51

      The Trustee in its individual or any other capacity may become the owner
or pledgee of Notes and may otherwise deal with the Company or an Affiliate with
the same rights it would have if it were not Trustee. Any Agent may do the same
with like rights. However, the Trustee is subject to Sections 9.10 and 9.11
hereof.

Section 9.04. Trustee's Disclaimer.

      The Trustee makes no representation as to the validity or adequacy of this
Indenture or the Notes, it shall not be accountable for the Company's use of the
proceeds from the Notes, and it shall not be responsible for any statement of
the Company in the Indenture or any statement in the Notes other than its
authentication or for compliance by the Company with the Registration Rights
Agreement.

Section 9.05. Notice of Defaults.

      If a Default or Event of Default occurs and is continuing and if it is
known to the Trustee, the Trustee shall mail to Holders a notice of the Default
or Event of Default within 90 days after it occurs. Except in the case of a
Default or Event of Default in payment on any Note, the Trustee may withhold the
notice if and so long as a committee of its Trust Officers in good faith
determines that withholding the notice is in the interests of Holders.

Section 9.06. Reports by Trustee to Holders.

      Within 60 days after the reporting date stated in Section 12.10, the
Trustee shall mail to Holders a brief report dated as of such reporting date
that complies with TIA (ss.) 313(a) if and to the extent required by such (ss.)
313(a). The Trustee also shall comply with TIA (ss.) 313(b)(2). The Trustee
shall also transmit by mail all reports as required by TIA (ss.) 313(c).

      A copy of each report at the time of its mailing to Holders shall be filed
with the SEC and each stock exchange on which the Notes are listed. The Company
shall notify the Trustee when the Notes are listed on any stock exchange.

Section 9.07. Compensation and Indemnity.

      The Company shall pay to the Trustee from time to time reasonable
compensation for its services hereunder. The Trustee's compensation shall not be
limited by any law on compensation of a trustee of an express trust. The Company
shall reimburse the Trustee upon request for all reasonable disbursements,
expenses and advances incurred or made by it. Such disbursements and expenses
may include the reasonable disbursements, compensation and expenses of the
Trustee's agents and counsel.

      The Company shall indemnify the Trustee against any loss or liability
incurred by it except as set forth in the next paragraph. The Trustee shall
notify the Company promptly of any claim for which it may seek indemnity. The
Company shall defend the claim and the Trustee shall cooperate in the defense.
The Trustee may have separate counsel and the Company shall pay the reasonable
fees, disbursements and expenses of such counsel. The Company need not pay for
any settlement made without its consent, which consent shall not be unreasonably
withheld.

      The Company need not reimburse any expense or indemnify against any loss
or liability incurred by the Trustee through negligence or bad faith.


                                       51
<PAGE>   52

      To secure the Company's payment obligations in this Section 9.07, the
Trustee shall have a lien prior to the Notes on all money or property held or
collected by the Trustee, except money or property held in trust to pay
principal and interest on particular Notes.

      Without prejudice to any other rights available to the Trustee under
applicable law, when the Trustee incurs expenses or renders services after an
Event of Default specified in Section 8.01(g) or (h) hereof occurs, the expenses
and the compensation for the services are intended to constitute expenses of
administration under any Bankruptcy Law.

      All amounts owing to the Trustee under this Section 9.07 shall be payable
by the Company in United States dollars.

Section 9.08. Replacement of Trustee.

      A resignation or removal of the Trustee and appointment of a successor
Trustee shall become effective only upon the successor Trustee's acceptance of
appointment as provided in this Section 9.08.

      The Trustee may resign by so notifying the Company. The Holders of a
majority in principal amount of the then outstanding Notes may remove the
Trustee by so notifying the Trustee and the Company. The Company may remove the
Trustee if:

            (a) the Trustee fails to comply with Section 9.10 hereof, unless the
      Trustee's duty to resign is stayed as provided in TIA (ss.) 310(b);

            (b) the Trustee is adjudged a bankrupt or an insolvent or an order
      for relief is entered with respect to the Trustee under any Bankruptcy
      Law;

            (c) a Custodian or public officer takes charge of the Trustee or its
      property; or

            (d) the Trustee becomes incapable of acting.

      If the Trustee resigns or is removed or if a vacancy exists in the office
of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holders
of a majority in principal amount of the then outstanding Notes may appoint a
successor Trustee to replace the successor Trustee appointed by the Company.

      If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company or the
Holders of at least 10% in principal amount of the then outstanding Notes may
petition any court of competent jurisdiction for the appointment of a successor
Trustee.

      If the Trustee fails to comply with Section 9.10 hereof, unless the
Trustee's duty to resign is stayed as provided in TIA (ss.) 310(b), any Holder
who has been a bona fide Holder of a Note for at least six months may petition
any court of competent jurisdiction for the removal of the Trustee and the
appointment of a successor Trustee.

      A successor Trustee shall deliver a written acceptance of its appointment
to the retiring Trustee and to the Company. Thereupon the resignation or removal
of the retiring Trustee shall become effective, and the successor Trustee shall
have all the rights, powers and duties of the Trustee under this Indenture. 


                                       52
<PAGE>   53

The successor Trustee shall mail a notice of its succession to Holders. The
retiring Trustee shall promptly transfer all property held by it as Trustee to
the successor Trustee, subject to the lien provided for in Section 9.07 hereof.
Notwithstanding replacement of the Trustee pursuant to this Section 9.08 hereof,
the Company's obligations under Section 9.07 hereof shall continue for the
benefit of the retiring trustee with respect to expenses and liabilities
incurred by it prior to such replacement.

Section 9.09. Successor Trustee by Merger, Etc.

      If the Trustee consolidates, merges or converts into, or transfers all or
substantially all of its corporate trust business to, another corporation, the
successor corporation without any further act shall be the successor Trustee.

Section 9.10. Eligibility; Disqualification.

      This Indenture shall always have a Trustee who satisfies the requirements
of TIA (ss.) 310(a)(1) and (5). The Trustee shall always have a combined capital
and surplus as stated in Section 12.10 hereof. The Trustee is subject to TIA
(ss.) 310(b). The indenture, dated as of June 12, 1996, between the Company and
The Chase Manhattan Bank (formerly known as Chemical Bank), as trustee, relating
to the Existing Convertible Notes shall be deemed to be specifically described
herein for the purposes of clause (i) of the first proviso contained in TIA
(ss.) 310(b).

Section 9.11. Preferential Collection of Claims Against Company.

      The Trustee is subject to TIA (ss.) 311(a), excluding any creditor
relationship listed in TIA (ss.) 311(b). A Trustee who has resigned or been
removed shall be subject to TIA (ss.) 311(a) to the extent indicated therein.

                                   ARTICLE X.
                             Discharge of Indenture

Section 10.01. Termination of Company's Obligations.

      This Indenture shall cease to be of further effect (except that the
Company's obligations under Sections 9.07 and 10.02 hereof shall survive) when
all outstanding Notes theretofore authenticated and issued have been delivered
to the Trustee for cancellation and the Company has paid all sums payable
hereunder.

Section 10.02. Repayment to Company.

      The Trustee and the Paying Agent shall promptly pay to the Company upon
request any excess money or securities held by them at any time.

      The Trustee and the Paying Agent shall pay to the Company upon request any
money held by them for the payment of principal or interest that remains
unclaimed for two years after the date upon which such payment shall have become
due; provided, however, that the Company shall have first caused notice of such
payment to the Company to be mailed to each Holder entitled thereto no less than
30 days prior to such payment. After payment to the Company, the Trustee and the
Paying Agent shall have no further liability with respect to such money and
Holders entitled to the money must look to the Company 


                                       53
<PAGE>   54

for payment as general creditors unless any applicable abandoned property law
designates another Person.

                                   ARTICLE XI.
                       Amendments, Supplements and Waivers

Section 11.01. Without Consent of Holders.

      The Company and the Trustee may amend or supplement this Indenture or the
Notes without the consent of any Holder:

            (a) to cure any ambiguity, defect or inconsistency;

            (b) to comply with Sections 5.12 and 7.01 hereof;

            (c) to provide for uncertificated Notes in addition to or in place
      of certificated Notes;

            (d) to make any change that does not adversely affect the interests
      hereunder of any Holder; or

            (e) to qualify the Indenture under the TIA or to comply with the
      requirements of the SEC in order to maintain the qualification of the
      Indenture under the TIA.

Section 11.02. With Consent of Holders.

      Subject to Section 8.07 hereof, the Company and the Trustee may amend or
supplement this Indenture or the Notes with the written consent of the Holders
of at least a majority in principal amount of the then outstanding Notes.
Subject to Sections 8.04 and 8.07 hereof, the Holders of a majority in principal
amount of the Notes then outstanding may also waive compliance in a particular
instance by the Company with any provision of this Indenture or the Notes.
However, without the consent of each Holder affected, an amendment, supplement
or waiver under this Section 11.02 may not:

            (a) reduce the principal amount of Notes whose Holders must consent
      to an amendment, supplement or waiver;

            (b) reduce the principal of or change the fixed maturity of any Note
      or alter the provisions of Sections 7 and 8 of the Notes;

            (c) reduce the rate of or change the time for payment of interest on
      any Note;

            (d) waive a default in the payment of the principal of, or interest
      or Liquidated Damages, if any, on, any Note (except a rescission of
      acceleration of the Notes by the Holders of at least a majority in
      aggregate principal amount of the Notes and a waiver of the payment
      default that resulted from such acceleration);

            (e) make any Note payable in money other than that stated in the
      Note;

            (f) make any change in Section 8.04 or 8.07 hereof;


                                       54
<PAGE>   55

            (g) waive a redemption payment with respect to any Note;

            (h) impair the right to convert the Notes into Common Stock;

            (i) modify Article V or VI in a manner adverse to the Holders of
      Notes; and

            (j) make any change in the foregoing amendment and waiver provisions
      of this Article XI.

      To secure a consent of the Holders under this Section 11.02, it shall not
be necessary for the Holders to approve the particular form of any proposed
amendment, supplement or waiver, but it shall be sufficient if such consent
approves the substance thereof.

      After an amendment, supplement or waiver under this Section 11.02 becomes
effective, the Company shall mail to Holders a notice briefly describing the
amendment or waiver.

Section 11.03. Compliance With Trust Indenture Act.

      Every amendment to this Indenture or the Notes shall be set forth in a
supplemental indenture that complies with the TIA as then in effect.

Section 11.04. Revocation and Effect of Consents.

      Until an amendment, supplement or waiver becomes effective, a consent to
it by a Holder of a Note is a continuing consent by the Holder and every
subsequent Holder of a Note or portion of a Note that evidences the same debt as
the consenting Holder's Note, even if notation of the consent is not made on any
Note. However, any such Holder or subsequent Holder may revoke the consent as to
his Note or portion of a Note if the Trustee receives the notice of revocation
before the date on which the Trustee receives an Officers' Certificate
certifying that the Holders of the requisite principal amount of Notes have
consented to the amendment, supplement or waiver.

      The Company may, but shall not be obligated to, fix a record date for the
purpose of determining the Holders entitled to consent to any amendment,
supplement or waiver. If a record date is fixed, then notwithstanding the
provisions of the immediately preceding paragraph, those Persons who were
Holders at such record date (or their duly designated proxies), and only those
Persons, shall be entitled to consent to such amendment, supplement or waiver or
to revoke any consent previously given, whether or not such Persons continue to
be Holders after such record date. No consent shall be valid or effective for
more than 90 days after such record date unless consents from Holders of the
principal amount of Notes required hereunder for such amendment or waiver to be
effective shall have also been given and not revoked within such 90-day period.

      After an amendment, supplement or waiver becomes effective it shall bind
every Holder, unless it is of the type described in any of clauses (a) through
(j) of Section 11.02 hereof. In such case, the amendment or waiver shall bind
each Holder who has consented to it and every subsequent Holder that evidences
the same debt as the consenting Holder's Note.

Section 11.05. Notation in or Exchange of Notes.

      The Trustee may place an appropriate notation about an amendment or waiver
on any Note 


                                       55
<PAGE>   56

thereafter authenticated. The Company in exchange for all Notes may issue and
the Trustee shall authenticate new Notes that reflect the amendment or waiver.

      Failure to make such notation on a Note or to issue a new Note as
aforesaid shall not affect the validity and effect of such amendment or waiver.

Section 11.06. Trustee Protected.

      The Trustee shall sign all supplemental indentures, except that the
Trustee may, but need not, sign any supplemental indenture that adversely
affects its rights.

                                  ARTICLE XII.
                                  Miscellaneous

Section 12.01. Trust Indenture Act Controls.

      This Indenture is subject to the provisions of the TIA that are required
to be incorporated into this Indenture (or, prior to the registration of the
Notes pursuant to the Registration Rights Agreement, would be required to be
incorporated into this Indenture if it were qualified under the TIA), and shall,
to the extent applicable, be governed by such provisions. If any provision of
this Indenture limits, qualifies, or conflicts with another provision which is
required (or would be so required) to be incorporated in this Indenture by the
TIA, the incorporated provision shall control.

Section 12.02. Notices.

      Any notice or communication by the Company or the Trustee to the other is
duly given if in writing and delivered in Person or mailed by first class mail
to the other's address stated in Section 12.10 hereof. The Company or the
Trustee by notice to the other may designate additional or different addresses
for subsequent notices or communications.

      Any notice or communication to a Holder shall be mailed by first class
mail to his address shown on the register kept by the Registrar. Failure to mail
a notice or communication to a Holder or any defect in it shall not affect its
sufficiency with respect to other Holders.

      If a notice or communication is mailed in the manner provided above within
the time prescribed, it is duly given, whether or not the addressee receives it.

      If the Company mails a notice or communication to Holders, it shall mail a
copy to the Trustee and each Agent at the same time.

      All other notices or communications shall be in writing.

      In case by reason of the suspension of regular mail service, or by reason
of any other cause, it shall be impossible to mail any notice as required by the
Indenture, then such method of notification as shall be made with the approval
of the Trustee shall constitute a sufficient mailing of such notice.

Section 12.03. Communication by Holders With Other Holders.

      Holders may communicate pursuant to TIA (ss.) 312(b) with other Holders
with respect to their 


                                       56
<PAGE>   57

rights under this Indenture or the Notes. The Company, the Trustee, the
Registrar and anyone else shall have the protection of TIA (ss.) 312(c).

Section 12.04. Certificate and Opinion as to Conditions Precedent.

      Upon any request or application by the Company to the Trustee to take any
action under this Indenture, the Company shall furnish to the Trustee:

            (a) an Officers' Certificate stating that, in the opinion of the
      signers, all conditions precedent, if any, provided for in this Indenture
      relating to the proposed action have been complied with; and

            (b) an Opinion of Counsel stating that, in the opinion of such
      counsel, all such conditions precedent have been complied with.

Section 12.05. Statements Required in Certificate or Opinion.

      Each certificate or opinion with respect to compliance with a condition or
covenant provided for in this Indenture (other than pursuant to Section 4.03)
shall include:

            (a) a statement that the Person signing such certificate or
      rendering such opinion has read such covenant or condition;

            (b) a brief statement as to the nature and scope of the examination
      or investigation upon which the statements or opinions contained in such
      certificate or opinion are based;

            (c) a statement that, in the opinion of such Person, such Person has
      made such examination or investigation as is necessary to enable such
      Person to express an informed opinion as to whether or not such covenant
      or condition has been complied with; and

            (d) a statement as to whether or not, in the opinion of such Person,
      such condition or covenant has been complied with.

Section 12.06. Rules by Trustee and Agents.

      The Trustee may make reasonable rules for action by, or a meeting of,
Holders. The Registrar or Paying Agent may make reasonable rules and set
reasonable requirements for its functions.

Section 12.07. Legal Holidays.

      A "Legal Holiday" is a Saturday, a Sunday or a day on which banking
institutions in the State of New York are not required to be open. If a payment
date is a Legal Holiday at a place of payment, payment may be made at that place
on the next succeeding day that is not a Legal Holiday, and no interest or
Liquidated Damages, if any, shall accrue for the intervening period. If any
other operative date for purposes of this Indenture shall occur on a Legal
Holiday then for all purposes the next succeeding day that is not a Legal
Holiday shall be such operative date.

Section 12.08. No Recourse Against Others.


                                       57
<PAGE>   58

      A director, officer, employee or stockholder, as such, of the Company
shall not have any liability for any obligations of the Company under the Notes
or the Indenture or for any claim based on, in respect of or by reason of such
obligations or their creation. Each Holder by accepting a Note waives and
releases all such liability. The waiver and release are part of the
consideration for the issue of the Notes.

Section 12.09. Counterparts and Facsimile Signatures.

      This Indenture may be executed by manual or facsimile signature in any
number of counterparts and by the parties hereto in separate counterparts, each
of which when so executed shall be deemed to be an original and all of which
taken together shall constitute one and the same agreement.

Section 12.10. Variable Provisions.

      "Officer" means the Chairman of the Board, the President, any Vice
President, the Treasurer, the Secretary, any Assistant Treasurer or any
Assistant Secretary of the Company.

      The first certificate pursuant to Section 4.03 hereof shall be for the
fiscal year ended on December 31, 1998.

      The reporting date for Section 9.06 hereof is March 15, of each year. The
first reporting date is March 15, 1999.

      The Trustee shall always have a combined capital and surplus of at least
$100,000,000 as set forth in its most recent published annual report of
condition.

      The Company's address is:

            NTL Incorporated
            110 East 59th Street, 26th Floor
            New York, New York 10022
            Attention:  Richard J. Lubasch, Esq.
                        Senior Vice President and General Counsel

      The Trustee's address is:

            The Chase Manhattan Bank
            450 West 33rd Street
            New York, New York 10001
            Attention:  Corporate Trustee
                        Administration Department

Section 12.11. Governing Law.

      THE INTERNAL LAWS OF THE STATE OF NEW YORK SHALL GOVERN THIS INDENTURE AND
THE NOTES, WITHOUT REGARD TO THE CONFLICT OF LAWS PROVISIONS THEREOF.

Section 12.12. No Adverse Interpretation of Other Agreements.


                                       58
<PAGE>   59

      This Indenture may not be used to interpret another indenture, loan or
debt agreement of the Company or an Affiliate. Any such indenture, loan or debt
agreement may not be used to interpret this Indenture.

Section 12.13. Successors.

      All agreements of the Company in this Indenture and the Notes shall bind
its successor. All agreements of the Trustee in this Indenture shall bind its
successor.

Section 12.14. Severability.

      In case any provision in this Indenture or in the Notes shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby.

Section 12.15. Table of Contents, Headings, Etc.

      The Table of Contents, Cross-Reference Table, and headings of the Articles
and Sections of this Indenture have been inserted for convenience of reference
only, are not to be considered a part hereof, and shall in no way modify or
restrict any of the terms or provisions hereof.


                                       59
<PAGE>   60

                                   SIGNATURES

      IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed, all as of the date first written above.

                                    NTL INCORPORATED, as Company

                                    By: /s/ Richard J. Lubasch
                                      Name: Richard J. Lubasch
                                     Title: Senior Vice President, 
                                              General Counsel and Secretary

                                    THE CHASE MANHATTAN BANK, as Trustee

                                    By: /s/ Andrew M. Deck
                                      Name: Andrew M. Deck
                                     Title: Vice President
<PAGE>   61
                                                                       EXHIBIT A

                         [FORM OF FACE OF INITIAL NOTE]

                              [Global Notes Legend]

      UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), NEW YORK, NEW
YORK, TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR
PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR
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.

      TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE, BUT
NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S
NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE SHALL BE LIMITED TO
TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE INDENTURE
REFERRED TO ON THE REVERSE HEREOF.

                            [Restricted Notes Legend]

      THE SECURITY (OR ITS PREDECESSOR) EVIDENCED HEREBY WAS ORIGINALLY ISSUED
IN A TRANSACTION EXEMPT FROM REGISTRATION UNDER SECTION 5 OF THE UNITED STATES
SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND THE SECURITY
EVIDENCED HEREBY AND ANY SHARES OF COMMON STOCK ISSUED UPON CONVERSION HEREOF
MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED IN THE ABSENCE OF SUCH
REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM. EACH PURCHASER OF THE
SECURITY EVIDENCED HEREBY IS HEREBY NOTIFIED THAT THE SELLER MAY BE RELYING ON
THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT PROVIDED BY
RULE 144A THEREUNDER. THE HOLDER OF THE SECURITY EVIDENCED HEREBY AGREES FOR THE
BENEFIT OF THE COMPANY THAT (A) SUCH SECURITY AND ANY SHARES OF COMMON STOCK
ISSUED UPON CONVERSION HEREOF MAY BE RESOLD, PLEDGED OR OTHERWISE TRANSFERRED,
ONLY (1) (a) TO A PERSON WHO THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT) IN A
TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (b) IN A TRANSACTION MEETING
THE REQUIREMENTS OF RULE 144 UNDER THE SECURITIES ACT, IF AVAILABLE, (c) OUTSIDE
THE UNITED STATES TO A NON-U.S. PERSON IN A TRANSACTION MEETING THE REQUIREMENTS
OF RULE 904 UNDER THE SECURITIES ACT OR (d) IN ACCORDANCE WITH ANOTHER EXEMPTION
FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT (AND BASED UPON AN
OPINION OF COUNSEL IF THE COMPANY SO REQUESTS), (2) TO THE COMPANY OR (3)
PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT AND, IN EACH CASE, IN ACCORDANCE
WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES OR ANY
OTHER APPLICABLE JURISDICTION AND (B) THE PURCHASER WILL, AND EACH SUBSEQUENT


                                      A-61
<PAGE>   62

PURCHASER IS REQUIRED TO, NOTIFY ANY SUBSEQUENT PURCHASER FROM IT OF THE
SECURITY EVIDENCED HEREBY OR ANY COMMON STOCK ISSUABLE UPON CONVERSION HEREOF OF
THE RESALE RESTRICTIONS SET FORTH IN (A) ABOVE.


                                      A-62
<PAGE>   63

No. ________
                                                                  $--------

                                    CUSIP No. [            ]/CINS No.
[            ]

                  7% CONVERTIBLE SUBORDINATED NOTE DUE 2008

      NTL Incorporated, a Delaware corporation (the "Company"), promises to pay
to __________________________ or registered assigns, the principal sum of
____________________ $[____________] [,or such other amount as is indicated on
Schedule A hereof* ,] on December 15, 2008, subject to the further provisions of
this Note set forth on the reverse hereof which further provisions shall for all
purposes have the same effect as if set forth at this place.

Interest Payment Dates:       June 15 and  December  15,  commencing  June 15,
1999

Record Dates:              June 1 and December 1

      IN WITNESS WHEREOF, NTL Incorporated has caused this Note to be signed
manually or by facsimile by one of its duly authorized officers.

                                     Dated:

                                    NTL INCORPORATED

                                    by:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION

This is one of the 7% Convertible 
Subordinated Notes due 2008 described in the
within-mentioned Indenture.

THE CHASE MANHATTAN BANK, as Trustee

By:______________________________________
      Authorized Officer

----------
* Applicable to Global Notes Only


                                      A-63
<PAGE>   64

                        [FORM OF REVERSE OF INITIAL NOTE]

                                NTL INCORPORATED

                  7% Convertible Subordinated Note due 2008

      1. Interest. NTL INCORPORATED, a Delaware corporation (the "Company"), is
the issuer of 7% Convertible Subordinated Notes due 2008 (the "Notes"). The
Notes will accrue interest at a rate of 7% per annum. The Company promises to
pay interest on the Notes in cash semiannually on each June 15 and December 15,
commencing on June 15, 1999, to Holders of record on the immediately preceding
June 1 and December 1, respectively. Interest on the Notes will accrue from the
most recent date to which interest has been paid, or if no interest has been
paid, from December 16, 1998. Interest will be computed on the basis of a
360-day year of twelve 30-day months. The Company will pay interest on overdue
principal at the interest rate borne by the Notes, compounded semiannually, and
it shall pay interest on overdue installments of interest and Liquidated
Damages, if any, (without regard to any applicable grace period) at the same
interest rate compounded semiannually. Any interest paid on this Note shall be
increased to the extent necessary to pay Additional Amounts as set forth in this
Note.

      2. Registration Rights. The holder of this Note is entitled to the
benefits of a Registration Rights Agreement, dated as of December 16, 1998,
among the Company and the Initial Purchasers (the "Registration Rights
Agreement"). Pursuant to the Registration Rights Agreement the Company has
agreed for the benefit of the Holders of the Notes, that (i) it will, at its
cost, within 90 days after the closing of the sale of the Notes (the "Closing"),
file a shelf registration statement (the "Shelf Registration Statement") with
the Securities and Exchange Commission (the "Commission") with respect to
resales of the Notes and the Common Stock issuable upon conversion thereof, (ii)
it will use its best efforts to cause such Shelf Registration Statement to be
declared effective within 180 days after the Closing, and (iii) it will use its
best efforts to keep such Shelf Registration Statement continuously effective
under the Securities Act, subject to certain exceptions specified in the
Registration Rights Agreement until the second anniversary of the date of the
Closing. If (a) the Company fails to file the Shelf Registration Statement
required by the Registration Rights Agreement on or before the date specified
above for such filing, (b) such Shelf Registration Statement is not declared
effective by the Commission on or prior to the date specified above for such
effectiveness, or (c) the Shelf Registration Statement is declared effective but
thereafter ceases to be effective or useable in connection with resales of
Transfer Restricted Securities (as defined in the Registration Rights Agreement)
during the periods specified in the Registration Rights Agreement (each such
event referred to in clauses (a) through (c) above a "Registration Default"),
then the Company will pay liquidated damages to each Holder of Transfer
Restricted Securities, with respect to the first 90-day period immediately
following the occurrence of such Registration Default in an amount equal to $.05
per week per $1,000 principal amount of Notes constituting Transfer Restricted
Securities held by such Holder ("Liquidated Damages"), provided that a Holder of
Transfer Restricted Securities shall not be entitled to the benefit of any
Liquidated Damages unless and until such Holder shall have furnished to the
Company the information required by Section 4(l) of the Registration Rights
Agreement. The amount of Liquidated Damages will increase by an additional $.05
per week per $1,000 principal amount constituting Transfer Restricted Securities
with respect to each subsequent 90-day period until all Registration Defaults
have been cured, up to a maximum amount of Liquidated Damages of $.50 per week
per $1,000 principal amount of Notes constituting Transfer Restricted
Securities. All accrued Liquidated Damages shall be paid by the Company on each
Interest Payment Date for which Liquidated Damages are owed to the holders of
Global Notes by wire transfer of immediately available funds or by federal funds
check and to holders of certificated Notes registered as such as of the
preceding Record Date by mailing checks to their registered 


                                      A-64
<PAGE>   65

addresses. Following the cure of all Registration Defaults, the accrual of
Liquidated Damages will cease.

      3. Additional Amounts. This Section 3 shall apply only in the event that
the Company becomes, or a successor to the Company is, a corporation organized
or existing under the laws of the United Kingdom, the Netherlands, the
Netherlands Antilles, Bermuda or the Cayman Islands. All payments made by the
Company on this Note shall be made without deduction for or on account of, any
and all present or future taxes, duties, assessments, or governmental charges of
whatever nature unless the deduction or withholding of such taxes, duties,
assessments or governmental charges is then required by law. If any deduction or
withholding for or on account of any present or future taxes, assessments or
other governmental charges of the United Kingdom, the Netherlands, the
Netherlands Antilles, Bermuda or the Cayman Islands (or any political
subdivision or taxing authority thereof or therein) shall at any time be
required in respect of any amounts to be paid by the Company under this Note,
the Company shall pay or cause to be paid such additional amounts ("Additional
Amounts") as may be necessary in order that the net amounts received by a Holder
of this Note after such deduction or withholding shall be not less than the
amounts specified in this Note to which the Holder of this Note is entitled;
provided, however, that the Company shall not be required to make any payment of
Additional Amounts for or on account of:

            (a) any tax, assessment or other governmental charge to the extent
      such tax, assessment or other governmental charge would not have been
      imposed but for (i) the existence of any present or former connection
      between such Holder (or between a fiduciary, settlor, beneficiary, member
      or shareholder of, or possessor of a power over, such Holder, if such
      Holder is an estate, nominee, trust, partnership or corporation), other
      than the holding of this Note or the receipt of amounts payable in respect
      of this Note, and the United Kingdom, the Netherlands, the Netherlands
      Antilles, Bermuda or the Cayman Islands (or any political subdivision or
      taxing authority thereof or therein) including, without limitation, such
      Holder (or such fiduciary, settlor, beneficiary, member, shareholder or
      possessor) being or having been a citizen or resident thereof or being or
      having been present or engaged in trade or business therein or having or
      having had a permanent establishment therein or (ii) the presentation of
      this Note (where presentation is required) for payment on a date more than
      30 days after the date on which such payment became due and payable or the
      date on which payment thereof is duly provided for, whichever occurs
      later, except to the extent that the Holder would have been entitled to
      Additional Amounts had this Note been presented on the last day of such
      period of 30 days;

            (b) any tax, assessment or other governmental charge that is imposed
      or withheld by reason of the failure to comply by the Holder of this Note
      or, if different, the beneficial owner of the interest payable on this
      Note, with a timely request of the Company addressed to such Holder or
      beneficial owner to provide information, documents or other evidence
      concerning the nationality, residence, identity or connection with the
      taxing jurisdiction of such Holder or beneficial owner which is required
      or imposed by a statute, regulation or administrative practice of the
      taxing jurisdiction as a precondition to exemption from all or part of
      such tax, assessment or governmental charge;

            (c) any estate, inheritance, gift, sales, transfer, personal
      property or similar tax, assessment or other governmental charge;

            (d) any tax, assessment or other governmental charge which is
      collectible otherwise than by withholding from payments of principal
      amount, redemption amount, Change 


                                      A-65
<PAGE>   66

      of Control Payment or interest with respect to a Note or withholding from
      the proceeds of a sale or exchange of a Note;

            (e) any tax, assessment or other governmental charge required to be
      withheld by any Paying Agent from any payment of principal amount,
      redemption amount, Change of Control Payment or interest with respect to a
      Note, if such payment can be made, and is in fact made, without such
      withholding by any other Paying Agent located inside the United States;

            (f) any tax, assessment or other governmental charge imposed on a
      Holder that is not the beneficial owner of a Note to the extent that the
      beneficial owner would not have been entitled to the payment of any such
      Additional Amounts had the beneficial owner directly held the Note;

            (g) any combination of items (a), (b), (c), (d), (e) and (f) above;

nor shall Additional Amounts be paid with respect to any payment of the
principal of, or any interest on, this Note to any Holder who is a fiduciary or
partnership or other than the sole beneficial owner of such payment to the
extent that a beneficiary or settlor would not have been entitled to any
Additional Amounts had such beneficiary or settlor been the Holder of this Note.
All references to principal amount or interest on the Notes in the Indenture or
the Notes shall include any Additional Amounts payable to the Company pursuant
to this Section 3.

      4. Method of Payment. The Company will pay interest on the Notes (except
defaulted interest) to the Persons who are registered Holders of Notes at the
close of business on the record date for the next interest payment date even
though Notes are canceled after the record date and on or before the interest
payment date. Holders must surrender Notes to a Paying Agent to collect
principal and premium payments. The Company will pay principal, premium, if any,
interest and Liquidated Damages, if any, in money of the United States that at
the time of payment is legal tender for payment of public and private debts.
However, the Company may pay principal, premium, if any, interest and Liquidated
Damages, if any, by check payable in such money. It may mail an interest or
Liquidated Damages check to a Holder's registered address. If a Holder so
requests, principal, premium, if any, interest and Liquidated Damages, if any,
may be paid by wire transfer of immediately available funds to an account
previously specified in writing by such Holder to the Company and the Trustee.

      5. Paying Agent, Conversion Agent and Registrar. The Trustee will act as
Paying Agent, Conversion Agent and Registrar in the City of New York, New York.
The Company may change any Paying Agent, Conversion Agent or Registrar without
prior notice. The Company or any of its Affiliates may act in any such capacity.

      6. Indenture. The Company issued the Notes under an Indenture, dated as of
December 16, 1998 (the "Indenture"), between the Company and The Chase Manhattan
Bank, as Trustee. The terms of the Notes include those stated in the Indenture
and those made part of the Indenture by the Trust Indenture Act of 1939 (15 U.S.
Code (ss.)(ss.) 77aaa-77bbbb) as in effect on the date of the Indenture. The
Notes are subject to, and qualified by, all such terms, certain of which are
summarized hereon, and Holders are referred to the Indenture and such Act for a
statement of such terms. The Notes are unsecured general obligations of the
Company limited to $600,000,000 in aggregate principal amount and subordinated
in right of payment to all existing and future Senior Debt of the Company.


                                      A-66
<PAGE>   67

      7. Optional Redemption. Except as provided in Section 8 hereof, the Notes
are not redeemable at the Company's option prior to December 15, 2001.
Thereafter, the Notes will be subject to redemption at the option of the
Company, in whole or in part, upon not less than 30 nor more than 60 days'
notice, at the redemption prices (expressed as percentages of principal amount
thereof) set forth below plus accrued and unpaid interest and Liquidated
Damages, if any, thereon to the applicable redemption date, if redeemed during
the twelve-month period beginning on December 15 of the years indicated below:

             Year                                       Percentage
             ----                                       ----------
             2001                                       104.375%
             2002                                       103.500%
             2003                                       102.625%
             2004                                       101.750%
             2005                                       100.875%
             2006 and thereafter                        100.000%
                                   
      8. Optional Tax Redemption. (a) The Notes may be redeemed at the option of
the Company, in whole but not in part, upon not less than 30 nor more than 60
days notice, at any time at a redemption price equal to the principal amount
thereof plus accrued and unpaid interest and Liquidated Damages, if any, to the
date fixed for redemption if after the date on which Section 3 of this Note
becomes applicable (the "Relevant Date") there has occurred any change in or
amendment to the laws (or any regulations or official rulings promulgated
thereunder) of the United Kingdom, the Netherlands, the Netherlands Antilles,
Bermuda or the Cayman Islands (or any political subdivision or taxing authority
thereof or therein), or any change in or amendment to the official application
or interpretation of such laws, regulation or rulings (a "Change in Tax Law")
which becomes effective after the Relevant Date, as a result of which the
Company is or would be so required on the next succeeding Interest Payment Date
to pay Additional Amounts with respect to the Notes as described under Section 3
hereof with respect to withholding taxes imposed by the United Kingdom, the
Netherlands, the Netherlands Antilles, Bermuda or the Cayman Islands (or any
political subdivision or taxing authority thereof or therein) (a "Withholding
Tax") and such Withholding Tax is imposed at a rate that exceeds the rate (if
any) at which Withholding Tax was imposed on the Relevant Date, provided,
however, that (i) this paragraph shall not apply to the extent that, at the
Relevant Date it was known or would have been known had professional advice of a
nationally recognized accounting firm in the United Kingdom, the Netherlands,
the Netherlands Antilles, Bermuda or the Cayman Islands, as the case may be,
been sought, that a Change in Tax Law in the United Kingdom, the Netherlands,
the Netherlands Antilles, Bermuda or the Cayman Islands was to occur after the
Relevant Date, (ii) no such notice of redemption may be given earlier than 90
days prior to the earliest date on which the Company would be obliged to pay
such Additional Amounts were a payment in respect of the Notes then due, (iii)
at the time such notice of redemption is given, such obligation to pay such
Additional Amount remains in effect and (iv) the payment of such Additional
Amounts cannot be avoided by the use of any reasonable measures available to the
Company.

      The Notes may also be redeemed, in whole but not in part, at any time at a
redemption price equal to the principal amount thereof plus accrued and unpaid
interest and Liquidated Damages, if any, to the date fixed for redemption if the
Person formed after the Relevant Date by a consolidation, amalgamation,
reorganization or reconstruction (or other similar arrangement) of the Company
or the Person into which the Company is merged after the Relevant Date or to
which the Company conveys, transfers or leases its properties and assets after
the Relevant Date substantially as an entirety 


                                      A-67
<PAGE>   68

(collectively, a "Subsequent Consolidation") is required, as a consequence of
such Subsequent Consolidation and as a consequence of a Change in Tax Law in the
United Kingdom, the Netherlands, the Netherlands Antilles, Bermuda or the Cayman
Islands occurring after the date of such Subsequent Consolidation to pay
Additional Amounts with respect to Notes with respect to Withholding Tax as
described under Section 3 hereof and such Withholding Tax is imposed at a rate
that exceeds the rate (if any) at which Withholding Tax was or would have been
imposed on the date of such Subsequent Consolidation, provided, however, that
this paragraph shall not apply to the extent that, at the date of such
Subsequent Consolidation it was known or would have been known had professional
advice of a nationally recognized accounting firm in the United Kingdom, the
Netherlands, the Netherlands Antilles, Bermuda or the Cayman Islands, as the
case may be, been sought, that a Change in Tax Law in the United Kingdom, the
Netherlands, the Netherlands Antilles, Bermuda or the Cayman Islands was to
occur after such date.

      The Company will also pay, or make available for payment, to Holders on
the Redemption Date any Additional Amounts (as described, but subject to the
exceptions referred to, in Section 3 hereof) resulting from the payment of such
Redemption Price.

      9. Notice of Redemption. Notice of redemption will be mailed at least 30
days but not more than 60 days before the redemption date to each Holder of the
Notes to be redeemed at his address of record. The Notes in denominations larger
than $1,000 may be redeemed in part but only in integral multiples of $1,000. In
the event of a redemption of less than all of the Notes, the Notes will be
chosen for redemption by the Trustee in accordance with the Indenture. On and
after the redemption date, interest ceases to accrue on the Notes or portions of
them called for redemption.

      If this Note is redeemed subsequent to a record date with respect to any
interest payment date specified above and on or prior to such interest payment
date, then any accrued interest will be paid to the Person in whose name this
Note is registered at the close of business on such record date.

      10. Mandatory Redemption. The Company will not be required to make
mandatory redemption or repurchase payments with respect to the Notes. There are
no sinking fund payments with respect to the Notes.

      11. Repurchase at Option of Holder. If there is a Change of Control, the
Company shall be required to offer to purchase on the Purchase Date all
outstanding Notes at a purchase price equal to 101% of the aggregate principal
amount thereof, plus accrued and unpaid interest and Liquidated Damages, if any,
to the Purchase Date. Holders of Notes that are subject to an offer to purchase
will receive a Change of Control offer from the Company prior to any related
Purchase Date and may elect to have such Notes or portions thereof in authorized
denominations purchased by completing the form entitled "Option of Holder to
Elect Purchase" appearing below.

      12. Subordination. The payment of the principal of, interest on or any
other amounts due on the Notes is subordinated in right of payment to all
existing and future Senior Debt of the Company, as described in the Indenture.
Each Holder, by accepting a Note, agrees to such subordination and authorizes
and directs the Trustee on its behalf to take such action as may be necessary or
appropriate to effectuate the subordination so provided and appoints the Trustee
as its attorney-in-fact for such purpose.

      13. Conversion. The holder of any Note has the right, exerciseable at any
time after 90 days following the Issuance Date and prior to the close of
business (New York time) on the date of the Note's 


                                      A-68
<PAGE>   69

maturity, to convert the principal amount thereof (or any portion thereof that
is an integral multiple of $1,000) into shares of Common Stock at the initial
Conversion Price of $61.25 per share, subject to adjustment under certain
circumstances as set forth in the Indenture, except that if a Note is called for
redemption, the conversion right will terminate at the close of business on the
Business Day immediately preceding the date fixed for redemption.

      To convert a Note, a holder must (1) complete and sign a conversion notice
substantially in the form set forth below, (2) surrender the Note to a
Conversion Agent, (3) furnish appropriate endorsements or transfer documents if
required by the Registrar or Conversion Agent and (4) pay any transfer or
similar tax, if required. Upon conversion, no adjustment or payment will be made
for interest or dividends, but if any holder surrenders a Note for conversion
after the close of business on the record date for the payment of an installment
of interest and prior to the opening of business on the next interest payment
date, then, notwithstanding such conversion, the interest payable on such
interest payment date will be paid to the registered holder of such Note on such
record date. In such event, such Note, when surrendered for conversion, need not
be accompanied by payment of an amount equal to the interest payable on such
interest payment date on the portion so converted. The number of shares issuable
upon conversion of a Note is determined by dividing the principal amount of the
Note converted by the Conversion Price in effect on the Conversion Date. No
fractional shares will be issued upon conversion but a cash adjustment will be
made for any fractional interest.

      A Note in respect of which a holder has delivered an "Option of Holder to
Elect Purchase" form appearing below exercising the option of such holder to
require the Company to purchase such Note may be converted only if the notice of
exercise is withdrawn as provided above and in accordance with the terms of the
Indenture. The above description of conversion of the Notes is qualified by
reference to, and is subject in its entirety by, the more complete description
thereof contained in the Indenture.

      14. Denominations, Transfer, Exchange. The Notes are in registered form,
without coupons, in denominations of $1,000 and integral multiples of $1,000.
The transfer of Notes may be registered, and Notes may be exchanged, as provided
in the Indenture. The Registrar may require a Holder, among other things, to
furnish appropriate endorsements and transfer documents and to pay any taxes and
fees required by law or permitted by the Indenture. The Registrar need not
exchange or register the transfer of any Note or portion of a Note selected for
redemption (except the unredeemed portion of any Note being redeemed in part).
Also, it need not exchange or register the transfer of any Note for a period of
15 days before a selection of Notes to be redeemed.

      15. Persons Deemed Owners. Except as provided in paragraph 4 of this Note,
the registered Holder of a Note may be treated as its owner for all purposes.

      16. Unclaimed Money. If money for the payment of principal or interest
remains unclaimed for two years, the Trustee and the Paying Agent shall pay the
money back to the Company at its written request. After that, Holders of Notes
entitled to the money must look to the Company for payment unless an abandoned
property law designates another Person and all liability of the Trustee and such
Paying Agent with respect to such money shall cease.

      17. Defaults and Remedies. The Notes shall have the Events of Default set
forth in Section 8.01 of the Indenture. Subject to certain limitations in the
Indenture, if an Event of Default occurs and is continuing, the Trustee by
notice to the Company or the Holders of at least 25% in aggregate principal
amount of the then outstanding Notes by notice to the Company and the Trustee
may declare all the Notes 


                                      A-69
<PAGE>   70

to be due and payable immediately, except that in the case of an Event of
Default arising from certain events of bankruptcy or insolvency, all unpaid
principal and interest accrued on the Notes shall become due and payable
immediately without further action or notice. The Holders of a majority in
principal amount of the Notes then outstanding by written notice to the Trustee
may rescind an acceleration and its consequences if the rescission would not
conflict with any judgment or decree and if all existing Events of Default have
been cured or waived except nonpayment of principal or interest that has become
due solely because of the acceleration. Holders may not enforce the Indenture or
the Notes except as provided in the Indenture. Subject to certain limitations,
Holders of a majority in principal amount of the then outstanding Notes issued
under the Indenture may direct the Trustee in its exercise of any trust or
power. The Company must furnish annually compliance certificates to the Trustee.
The above description of Events of Default and remedies is qualified by
reference, and subject in its entirety, to the more complete description thereof
contained in the Indenture.

      18. Amendments, Supplements and Waivers. Subject to certain exceptions,
the Indenture or the Notes may be amended or supplemented with the consent of
the Holders of at least a majority in principal amount of the then outstanding
Notes (including consents obtained in connection with a tender offer or exchange
offer for Notes), and any existing default may be waived with the consent of the
Holders of a majority in principal amount of the then outstanding Notes. Without
the consent of any Holder, the Indenture or the Notes may be amended among other
things, to cure any ambiguity, defect or inconsistency, to provide for
uncertificated Notes in addition to or in place of certificated Notes, to
provide for assumption of the Company's obligations to Holders, to make any
change that does not adversely affect the rights of any Holder or to qualify the
Indenture under the TIA or to comply with the requirements of the SEC in order
to maintain the qualification of the Indenture under the TIA.

      19. Trustee Dealings with the Company. The Trustee, in its individual or
any other capacity may become the owner or pledgee of the Notes and may
otherwise deal with the Company or an Affiliate with the same rights it would
have, as if it were not Trustee, subject to certain limitations provided for in
the Indenture and in the TIA. Any Agent may do the same with like rights.

      20. No Recourse Against Others. A director, officer, employee or
stockholder, as such, of the Company shall not have any liability for any
obligations of the Company under the Notes or the Indenture or for any claim
based on, in respect of or by reason of such obligations or their creation. Each
Holder of the Notes by accepting a Note waives and releases all such liability.
The waiver and release are part of the consideration for the issue of the Notes.

      21. Governing Law. THE INTERNAL LAWS OF THE STATE OF NEW YORK SHALL GOVERN
THE INDENTURE AND THE NOTES WITHOUT REGARD TO CONFLICT OF LAW PROVISIONS
THEREOF.

      22. Authentication. The Notes shall not be valid until authenticated by
the manual signature of an authorized officer of the Trustee or an
authenticating agent.

      23. Abbreviations. Customary abbreviations may be used in the name of a
Holder or an assignee, such as: TEN COM (= tenants in common), TEN ENT (=
tenants by the entireties), JT TEN (= joint tenants with right of survivorship
and not as tenants in common), CUST (- Custodian), and UGMA (= Uniform Gifts to
Minors Act).

      The Company will furnish to any Holder of the Notes upon written request
and without charge a 


                                      A-70
<PAGE>   71

copy of the Indenture. Request may be made to:

          NTL Incorporated
          110 East 59th Street, 26th Floor
          New York, New York 10022
          Attention of: Richard J. Lubasch, Esq.
                     Senior Vice President and General Counsel


                                      A-71
<PAGE>   72

                                 ASSIGNMENT FORM

                 To assign this Note, fill in the form below:

                 (I) or (we) assign and transfer this Note to
              -------------------------------------------------
             (Insert assignee's social security or tax I.D. no.)

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

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

and irrevocably appoint _________________________________ agent to transfer this
Note on the books of the Company. The agent may substitute another to act for
him.

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

      Date: __________________

  Signature Guarantee: * ____________________________________________

      In connection with any transfer of any of the Notes evidenced by this
      certificate occurring prior to the date that is two years after the later
      of the date of original issuance of such Notes and the last date, if any,
      on which such Notes were owned by the Company or any Affiliate of the
      Company, the undersigned confirms that such Notes are being transferred:

CHECK ONE BOX BELOW

      (1)   to the Company or any subsidiary thereof,

      (2)   to a qualified institutional buyer in compliance with Rule 144A,

      (3)   outside the United States in compliance with Rule 904 under the
            Securities Act,

      (4)   pursuant to the exemption from registration provided by Rule 144
            under the Securities Act (if available) or

      (5)   pursuant to an effective registration statement under the Securities
            Act.

----------
*     Signature must be guaranteed by a commercial bank, trust company or member
      firm of the New York Stock Exchange


                                      A-72
<PAGE>   73

                                                    --------------------------
                                                      Signature

Signature Guarantee*

--------------------------
Signature must be guaranteed

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

            TO BE COMPLETED BY PURCHASER IF (2) ABOVE IS CHECKED.

            The undersigned represents and warrants that it is purchasing this
Note for its own account or an account with respect to which it exercises sole
investment discretion and that it and any such account is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act of
1933, and is aware that the sale to it is being made in reliance on Rule 144A
and acknowledges that it has received such information regarding the Company as
the undersigned has requested pursuant to Rule 144A or has determined not to
request such information and that it is aware that the transferor is relying
upon the undersigned's foregoing representations in order to claim the exemption
from registration provided by Rule 144A.

Date: _____________________

___________________________

*     Signature must be guaranteed by a commercial bank, trust company or member
      firm of the New York Stock Exchange.

                NOTICE: To be executed by an executive officer


                                      A-73
<PAGE>   74

                       OPTION OF HOLDER TO ELECT PURCHASE

            If you want to elect to have this Note or a portion thereof
repurchased by the Company pursuant to Section 3.09 or 4.07 of the Indenture,
check the box: [ ]

            If the purchase is in part, indicate the portion (in denominations
of $1,000 or any integral multiple thereof) to be purchased:____________________

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

      Date: ________________________

      Signature Guarantee:**/

----------
**/   Signature must be guaranteed by a commercial bank, trust company or member
      firm of the New York Stock Exchange.


                                      A-74
<PAGE>   75

                               ELECTION TO CONVERT

To NTL Incorporated

            The undersigned owner of this Note hereby irrevocably exercises the
option to convert this Note, or the portion below designated, into Common Stock
of NTL Incorporated in accordance with the terms of the Indenture referred to in
this Note, and directs that the shares issuable and deliverable upon conversion,
together with any check in payment for fractional shares, be issued in the name
of and delivered to the undersigned, unless a different name has been indicated
in the assignment below. If the shares are to be issued in the name of a person
other than the undersigned, the undersigned will pay all transfer taxes payable
with respect thereto.

            Any holder of Notes, upon the exercise of its conversion rights in
accordance with the terms of the Indenture and the Note, agrees to be bound by
the terms of the Registration Rights Agreement relating to the Common Stock
issuable upon conversion of the Notes.

Date:

      in whole ___

                                          Portions of Note to be converted
                                          ($1,000 or integral  multiples
                                          thereof): $______________

                                    Signature

                                          Please Print or Typewrite Name and
                                          Address, Including Zip Code, and
                                          Social Security or Other
                                          Identifying Number

                                    Signature Guarantee:  *

----------
*     Signature must be guaranteed by a commercial bank, trust company or member
      firm of the New York Stock Exchange.


                                      A-75
<PAGE>   76

                        [TO BE ATTACHED TO GLOBAL NOTES]

                                   SCHEDULE A

                          SCHEDULE OF PRINCIPAL AMOUNT

            The initial principal amount of this Global Note shall be
$__________________. The following increases or decreases in the principal
amount of this Global Note have been made:

--------------------------------------------------------------------------------
   Amount of        Amount of                    Signature of       Date of
  decrease in      increase in     Principal      authorized       exchange
   principal        principal      amount of      officer of    following such
 amount of this  amount of this   this Global     Trustee or      decrease or
  Global Note      Global Note        Note      Notes Custodian    increase
--------------------------------------------------------------------------------

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

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

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

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

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

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

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

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

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

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

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

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

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


                                      A-76
<PAGE>   77

                                                                       EXHIBIT B

                  FORM OF TRANSFER CERTIFICATE FOR TRANSFER
                FROM RULE 144A GLOBAL NOTE OR RESTRICTED NOTE
                           TO REGULATION S GLOBAL NOTE
            (Transfers pursuant to (ss.) 2.06(a)(ii) or 2.06(a)(vii)
                                of the Indenture)

The Chase Manhattan Bank, as Trustee
450 West 33rd Street
New York, New York  10001
Attn:    Corporate Trustee Administration Department

            Re: NTL Incorporated 7% Convertible Subordinated Notes due
                2008 (the "Notes")

            Reference is hereby made to the Indenture, dated as December 16,
1998 (the "Indenture"), between NTL Incorporated, as Issuer, and The Chase
Manhattan Bank, as Trustee.

            This letter relates to $[ ] [check one] (i) aggregate principal
amount of Notes which are held in the form of the Rule 144A Global Note (CUSIP
No. 629407AK3) with the Depositary or (ii) principal amount of Restricted Note
(CUSIP No. 629407AM9) registered, in either case, in the name of [name of
transferor] (the "Transferor") to effect the transfer of the Notes in exchange
for an equivalent beneficial interest in the Regulation S Global Notes.

            In connection with such request, the Transferor does hereby certify
that such transfer has been effected in accordance with (i) the transfer
restrictions set forth in the Notes and (ii) that:

            (1) the offer of the Notes was not made to a Person in the United
      States;

            (2) the transaction was executed in, on or through the facilities of
      a designated offshore securities market and neither the Transferor nor any
      Person acting on its behalf knows that the transaction was pre-arranged
      with a buyer in the United States;

            (3) no directed selling efforts have been made in contravention of
      the requirements of Rule 903(b) or 904(b) of Regulation S, as applicable;
      and

            (4) the transaction is not part of a plan or scheme to evade the
      registration requirements of the United States Securities Act of 1933, as
      amended (the "Securities Act").

            In addition, if the sale is made during a distribution compliance
period and the provisions of Rule 903(c)(2) or (3) or Rule 904(c)(1) of
Regulation S are applicable thereto, we confirm that such sale has been made in
accordance with the applicable provisions of Rule 903(c)(2) or (3) or Rule
904(c)(1), as the case may be.

            You and the Company are entitled to rely upon this letter and are
irrevocably authorized to produce this letter or a copy hereof to any interested
party in any administrative or legal proceedings or 


                                      B-77
<PAGE>   78

official inquiry with respect to the matters covered hereby. Capitalized terms
used in this certificate and not otherwise defined in the Indenture have the
meanings set forth in Regulation S.

                                                [Name of Transferor]

                                                By:___________________________

                                                   Name:
                                                   Title:

Dated:

cc: NTL Incorporated
    110 East 59th Street
    New York, New York  10022
    Attn:   Richard J. Lubasch, Esq.
         Senior Vice President and General Counsel


                                      B-78
<PAGE>   79

                                                                       EXHIBIT C

                  FORM OF TRANSFER CERTIFICATE FOR TRANSFER
               FROM REGULATION S GLOBAL NOTE OR RESTRICTED NOTE
                            TO RULE 144A GLOBAL NOTE
            (Transfers pursuant to (ss.) 2.06(a)(iii) or 2.06(a)(vi)
                                of the Indenture)

The Chase Manhattan Bank, as Trustee
450 West 33rd Street
New York, New York  10001
Attn:  Corporate Trustee Administration Department

            Re: NTL Incorporated 7% Convertible Subordinated Notes due
                2008 (the "Notes")

            Reference is hereby made to the Indenture, dated as of December 16,
1998 (the "Indenture"), between NTL Incorporated, as Issuer, and The Chase
Manhattan Bank, as Trustee. Capitalized terms used but not defined herein shall
have the respective meanings given them in the Indenture.

            This letter relates to $[ ] [check one] (i) aggregate principal
amount of Notes which are held in the form of the Regulation S Global Note
(CUSIP No. ____) with the Depositary or (ii) principal amount of Restricted Note
(CUSIP No. 629407AM9) registered, in each case, in the name of [name of
transferor] (the "Transferor") to effect the transfer of the Notes in exchange
for an equivalent beneficial interest in the Rule 144A Global Note.

            In connection with such request, and in respect of such Notes the
Transferor does hereby certify that such Notes are being transferred in
accordance with (i) the transfer restrictions set forth in the Notes and (ii)
Rule 144A under the United States Securities Act of 1933, as amended, to a
transferee that the Transferor reasonably believes is purchasing the Notes for
its own account or an account with respect to which the transferee exercises
sole investment discretion and the transferee and any such account is a
"qualified institutional buyer" within the meaning of Rule 144A, in a
transaction meeting the requirements of Rule 144A and in accordance with
applicable securities laws of any state of the United States or any other
jurisdiction.

                                                [Name of Transferor],

                                                By:___________________________
                                                   Name:
                                                   Title:
Dated:

cc:  NTL Incorporated
    110 East 59th Street
    New York, New York  10022
    Attn:  Richard J. Lubasch, Esq.
         Senior Vice President and General Counsel

                                     C-79
<PAGE>   80

                                                                       EXHIBIT D

                  FORM OF TRANSFER CERTIFICATE FOR TRANSFER
                         FROM GLOBAL NOTE OR RESTRICTED
                             NOTE TO RESTRICTED NOTE
                    (Transfers pursuant to (ss.) 2.06(a)(iv)
                      or (ss.) 2.06(a)(v) of the Indenture)

The Chase Manhattan Bank, as Trustee
450 West 33rd Street
New York, New York  10001
Attn:  Corporate Trustee Administration Department

            Re: NTL Incorporated 7% Convertible Subordinated Notes due
                2008 (the "Notes")

            Reference is hereby made to the Indenture, dated as of December 16,
1998 (the "Indenture"), between NTL Incorporated, as Issuer, and The Chase
Manhattan Bank, as Trustee. Capitalized terms used but not defined herein shall
have the respective meanings given them in the Indenture.

            This letter relates to $[ ] aggregate principal amount of Notes
which are held [in the form of the [Rule 144A/Regulation S] [Global]
[Restricted] Note (CUSIP No. [ ] CINS No. [ ]) [with the Depositary] in the name
of [name of transferor] (the "Transferor") to effect the transfer of the Notes.

            In connection with such request, and in respect of such Notes, the
Transferor does hereby certify that such Notes are being transferred (i) in
accordance with the transfer restrictions set forth in the Notes and (ii) in
accordance with applicable securities laws of any state of the United States or
any other jurisdiction.

*Insert, if appropriate.

                                                [Name of Transferor],

                                                By:___________________________
                                                   Name:
                                                   Title:
Dated:

cc: NTL Incorporated
    110 East 59th Street
    New York, New York  10022
    Attn:  Richard J. Lubasch, Esq.
         Senior Vice President and General Counsel


                                      D-80
<PAGE>   81

                                                                       EXHIBIT E

                     FORM OF ACCREDITED INVESTOR CERTIFICATE

NTL Incorporated
110 East 59th Street
New York, New York  10022

      We are delivering this letter in connection with our purchase of $
principal amount of 7% Convertible Subordinated Notes due 2008 (the "Convertible
Notes") of NTL Incorporated, a Delaware corporation (the "Company") issued
pursuant to an indenture, dated December 16, 1998, between the Company and The
Chase Manhattan Bank, as trustee, as described in the Offering Memorandum (the
"Offering Memorandum") relating to such offering.

      We hereby confirm that:

            (i) we are an "accredited investor" within the meaning of Rule 501
      (a) (1), (2), (3), (4) or (7) under the Securities Act of 1933, as amended
      (the "Securities Act"), or an entity in which all of the equity owners are
      accredited investors within the meaning of Rule 501(a) (1), (2), (3), (4)
      or (7), under the Securities Act (an "Accredited Investor");

            (ii) (A) any purchase of the Convertible Notes by us will be for our
      own account or for the account of one or more other Accredited Investors
      or as fiduciary for the account of one or more trusts, each of which is an
      "accredited investor" within the meaning of Rule 501 (a) (7) under the
      Securities Act and for each of which we exercise sole investment
      discretion or (B) we are a "bank," within the meaning of Section 3(a) (2)
      of the Securities Act, or a "savings and loan association" or other
      institution described in Section 3(a) (5) (A) of the Securities Act that
      is acquiring the Convertible Notes as fiduciary for the account of one or
      more institutions for which we exercise sole investment discretion;

            (iii) in the event that we purchase any of the Convertible Notes, we
      will acquire Convertible Notes having a minimum purchase price of not less
      than $100,000 for our own account or for any separate account for which we
      are acting;

            (iv) we have such knowledge and experience in financial and business
      matters that we are capable of evaluating the merits and risks of
      purchasing the Convertible Notes;

            (v) we are not acquiring the Convertible Notes with a view to any
      distribution thereof in a transaction that would violate the Securities
      Act or the securities laws of any State of the United States or any other
      applicable jurisdictions; provided that the disposition of our property
      and the property of any accounts for which we are acting as fiduciary
      shall remain at all times within our control;

            (vi) we have received a copy of the Offering Memorandum and
      acknowledge that we have had access to such financial and other
      information, and have been afforded the opportunity to ask such questions
      of representatives of the Company and receive answers 


                                      E-81
<PAGE>   82

      thereto, as we deem necessary in connection with our decision to purchase
      the Convertible Notes.

            We understand that the Convertible Notes are being offered in a
      transaction not involving any public offering within the meaning of the
      Securities Act, that the Convertible Notes have not been registered under
      the Securities Act, and we agree, on our own behalf and on behalf of each
      account for which we acquire any Convertible Notes, that the Convertible
      Notes may be offered, resold, pledged or otherwise transferred only (i)
      inside the United States to a person whom we reasonably believe to be a
      Qualified Institutional Buyer (as defined in Rule 144A under the
      Securities Act) in a transaction meeting the requirements of Rule 144A, in
      a transaction meeting the requirements of Rule 144 under the Securities
      Act, if available, or outside the United States to a non-U.S. person in a
      transaction meeting the requirements of Rule 904 under the Securities Act,
      or unless the holder thereof is the initial accredited investor, in
      accordance with another exemption from the registration requirements of
      the Securities Act (and based upon an opinion of counsel if the Company so
      requests), (ii) to the Company or (iii) pursuant to an effective
      registration statement under the Securities Act, and, in each case, in
      accordance with any applicable securities laws of any State of the United
      States or any other applicable jurisdiction. We understand that the
      registrar and transfer agent will not be required to accept for
      registration of transfer any Convertible Notes, except upon presentation
      of evidence satisfactory to the Company, as applicable, that the foregoing
      restrictions on transfer have been complied with. We further understand
      that Convertible Notes will be in the form of definitive physical
      certificates and that any such certificates will bear a legend reflecting
      the substance of this paragraph. We further agree to provide any person
      purchasing the Convertible Notes or the Common Stock issuable upon
      conversion thereof (other than pursuant to clause (iii) of this paragraph)
      from us a notice advising such purchaser that resales of such securities
      are restricted as stated therein.

      We acknowledge that you, the Company, and others will rely upon our
confirmations, acknowledgments and agreements set forth herein, and we agree to
notify you promptly in writing if any of our representations or warranties
herein ceases to be accurate and complete.

      THIS LETTER SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE
LAWS OF THE STATE OF NEW YORK.

Dated:           .

                                    ________________________________________

                                    By: ____________________________________

                                    Its: ____________________________________

                                    Address:________________________________

                                    _________________________________

cc:   The Chase Manhattan Bank, as Trustee
      450 West 33rd Street
      New York, New York  10001
      Attn:  Corporate Trustee Administration Department