EXHIBIT 4.2








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                           IRON MOUNTAIN INCORPORATED

                                       AND

                              THE BANK OF NEW YORK,
                                   as Trustee


                    8 5/8% Senior Subordinated Notes due 2013


                          FIRST SUPPLEMENTAL INDENTURE


                            Dated as of April 3, 2001


                                       TO


                             SUBORDINATED INDENTURE


                            Dated as of April 3, 2001




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                                TABLE OF CONTENTS



                                                                            PAGE
                                                                        
ARTICLE 1. DEFINITIONS........................................................1

  Section 1.1. DEFINITIONS....................................................1

ARTICLE 2. FORM AND TERMS OF THE NOTES.......................................19

  Section 2.1. FORM AND DATING...............................................19
  Section 2.2. EXECUTION AND AUTHENTICATION..................................20
  Section 2.3. DEPOSITORY AND PAYING AGENT FOR NOTES.........................20
  Section 2.4. TRANSFER AND EXCHANGE OF NOTES................................20
  Section 2.5. REDEMPTION....................................................22
  Section 2.6. COVENANTS.....................................................25
     (a) Reports.............................................................25
     (b) Restricted Payments.................................................26
     (c) Incurrence of Indebtedness and Issuance of Preferred Stock..........28
     (d) Liens...............................................................29
     (e) Dividend and Other Payment Restrictions Affecting
           Restricted Subsidiaries...........................................30
     (f) Transactions with Affiliates........................................31
     (g) Certain Senior Subordinated Debt....................................32
     (h) Additional Subsidiary Guarantees....................................32
     (i) Designation of Unrestricted Subsidiaries............................33
     (j) Limitation on Sale and Leaseback Transactions.......................34
     (k) Asset Sales.........................................................34
     (l) Change of Control Offer.............................................37
     (m) Corporate Existence.................................................38
  Section 2.7.  MERGERS, CONSOLIDATIONS OR SALE OF ASSETS....................39
  Section 2.8.  EVENTS OF DEFAULT............................................40
  Section 2.9.  ACCELERATION.................................................41
  Section 2.10. AMENDMENTS AND WAIVERS.......................................42
  Section 2.11. SUBSIDIARY GUARANTEES........................................45
  Section 2.12. LEGAL DEFEASANCE AND COVENANT DEFEASANCE.....................45
  Section 2.13. SUBORDINATION................................................45

ARTICLE 3. MISCELLANEOUS.....................................................46

  Section 3.1.  EFFECT OF HEADINGS...........................................46
  Section 3.2.  SUCCESSORS AND ASSIGNS.......................................46
  Section 3.3.  SEPARABILITY CLAUSE..........................................46
  Section 3.4.  GOVERNING LAW................................................47
  Section 3.5   FIRST SUPPLEMENT TO SUPERSEDE INDENTURE......................47


EXHIBITS

Exhibit A FORM OF NOTES
Exhibit B FORM OF SUPPLEMENTAL INDENTURE


                                        i




     THIS FIRST SUPPLEMENTAL INDENTURE, dated as of April 3, 2001 ("FIRST
SUPPLEMENTAL INDENTURE"), is by and among IRON MOUNTAIN INCORPORATED, a
Pennsylvania corporation, having its principal office at 745 Atlantic Avenue,
Boston, Massachusetts 02111, the Guarantors signatory hereto and THE BANK OF NEW
YORK, a New York banking corporation, as trustee, having its principal corporate
trust office at 101 Barclay Street, 21st Floor, New York, NY 10286.

                                   WITNESSETH:

     WHEREAS, the Company and The Bank of New York, acting as trustee, executed
and delivered a Subordinated Indenture, dated as of April 3, 2001 (the
"INDENTURE"), to provide for the issuance by the Company from time to time of
Securities to be issued in one or more series as provided in the Indenture;

     WHEREAS, the issuance and sale of up to $500,000,000 aggregate principal
amount of a series of the Company's Securities (the "NOTES") have been
authorized by resolutions adopted by the Board of Directors of the Company on
March 6, 2001;

     WHEREAS, the Company desires to issue and sell $225,000,000 aggregate
principal amount of the Notes on the date hereof;

     WHEREAS, the Company desires to enter into this First Supplemental
Indenture pursuant to Section 9.1(e) of the Indenture to supplement the
Indenture to establish the form and terms of the Notes; and

     NOW, THEREFORE, for and in consideration of the premises stated herein and
the purchase of the Notes by the Holders thereof, the parties hereto hereby
enter into this First Supplemental Indenture, for the equal and proportionate
benefit of all Holders of Notes, as follows:



                                   ARTICLE 1.

                                   DEFINITIONS

Section 1.1. DEFINITIONS.

     (a) All of the terms used in this First Supplemental Indenture which are
defined in the Indenture shall have the meanings specified in the Indenture,
unless otherwise defined herein (in which case they shall have the meanings
defined herein for the purposes of the Indenture as well as for the First
Supplemental Indenture) or unless the context otherwise requires, and for the
purposes of this First Supplemental Indenture, the following terms have the
meanings set forth in this Section:

     "ACQUIRED DEBT" means, with respect to any specified Person:

          (1) Indebtedness of any other Person, existing at the time such other
     Person merged with or into or became a Subsidiary of such specified Person,
     including Indebtedness incurred in connection with, or in contemplation of,
     such other Person merging with or into or becoming a Subsidiary of such
     specified Person and

          (2) Indebtedness encumbering any asset acquired by such specified
     Person.




     "ACQUISITION EBITDA" means, as of any date of determination, with respect
to an Acquisition EBITDA Entity, the sum of:

          (1) EBITDA of such Acquisition EBITDA Entity for its last fiscal
     quarter for which financial statements are available at such date of
     determination (adjusted to give pro forma effect to any acquisition or
     disposition of a business or Person by such Acquisition EBITDA Entity
     consummated during the period covered by, or after the date of, such
     quarterly financial statements), multiplied by four (or if such quarterly
     statements are not available, EBITDA for the most recent fiscal year for
     which financial statements are available), plus

          (2) projected quantifiable improvements in operating results (on an
     annualized basis) due to cost reductions calculated in good faith by the
     Company or one of its Restricted Subsidiaries, as certified by an Officers'
     Certificate filed with the Trustee, without giving effect to any operating
     losses of the acquired Person.

     "ACQUISITION EBITDA ENTITY" means, as of any date of determination, a
business or Person:

          (1) which has been acquired by the Company or one of its Restricted
     Subsidiaries and with respect to which financial results on a consolidated
     basis with the Company have not been made available for an entire fiscal
     quarter or

          (2) which is to be acquired in whole or in part with Indebtedness, the
     incurrence of which will require the calculation on such date of the
     Acquisition EBITDA of such Acquisition EBITDA Entity for purposes of
     Section 4.8 of the Indenture.

     "ADDITIONAL NOTES" means up to $275,000,000 aggregate principal amount of
the Company's 8 5/8% Senior Subordinated Notes due 2013 (other than the Initial
Notes) issued under this First Supplemental Indenture in accordance with Section
2.2 hereof as part of the same series as the Initial Notes.

     "ADJUSTED EBITDA" means, as of any date of determination and without
duplication, the sum of:

          (1) EBITDA of the Company and its Restricted Subsidiaries for the most
     recent fiscal quarter for which internal financial statements are available
     at such date of determination, multiplied by four and

          (2) Acquisition EBITDA of each business or Person that is an
     Acquisition EBITDA Entity as of such date of determination, multiplied by a
     fraction, (i) the numerator of which is three minus the number of months
     (and/or any portion thereof) in such most recent fiscal quarter for which
     the financial results of such Acquisition EBITDA Entity are included in the
     EBITDA of the Company and its Restricted Subsidiaries under clause (1)
     above, and (ii) the denominator of which is three.


                                       2





     The effects of unusual items, including merger-related expenses permitted
     to be shown as a separate line item on a statement of operations in
     accordance with GAAP, or non-recurring items in respect of the Company, a
     Restricted Subsidiary or an Acquisition EBITDA Entity occurring in any
     period shall be excluded in the calculation of Adjusted EBITDA.

     "AFFILIATE" of any specified Person means any other Person directly or
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 MEMBERS" means members of, or participants in, the Depository.

     "ATTRIBUTABLE INDEBTEDNESS" in respect of a Sale and Leaseback Transaction
means, as of the time of determination, the greater of:

          (1) the fair market value of the property subject to such arrangement
     (as determined by the Board of Directors of the Company) and

          (2) the present value (discounted at the rate of interest implicit in
     such transaction) of the total obligations of the lessee for rental
     payments during the remaining terms of the lease included in such Sale and
     Leaseback Transaction (including any period for which such lease has been
     extended).

     "CAPITAL LEASE OBLIGATION" means, at the time any determination thereof is
to be made, the amount of the liability in respect of a capital lease that would
at such time be so required to be capitalized on the balance sheet in accordance
with GAAP.

     "CAPITAL STOCK" means any and all shares, interests, participations, rights
or other equivalents (however designated) of corporate stock, including, without
limitation, with respect to partnerships, partnership interests (whether general
or limited) and any other interest or participation that confers on a Person the
right to receive a share of the profits and losses of, or distributions of
assets of, such partnership.

     "CASH EQUIVALENTS" means:

          (1) securities with maturities of one year or less from the date of
     acquisition, issued, fully guaranteed or insured by the United States
     Government or any agency thereof;

          (2) certificates of deposit, time deposits, overnight bank deposits,
     bankers acceptances and repurchase agreements issued by a Qualified Issuer
     having maturities of 270 days or less from the date of acquisition;



                                       3




          (3) commercial paper of an issuer rated at least A-2 by Standard &
     Poor's Rating Group, a division of McGraw Hill, Inc., or P-2 by Moody's
     Investors Service, or carrying an equivalent rating by a nationally
     recognized rating agency if both of the two named rating agencies cease
     publishing ratings of investments and having maturities of 270 days or less
     from the date of acquisition;

          (4) money market accounts or funds with or issued by Qualified
     Issuers; and

          (5) Investments in money market funds substantially all of the assets
     of which are comprised of securities and other obligations of the types
     described in clauses (1) through (3) above.

     "CHANGE OF CONTROL" means the occurrence of any of the following events:

          (1) any "person" or "group" (as such terms are used in Sections 13(d)
     and 14(d) of the Exchange Act), other than the Principal Stockholders (or
     any of them), is or becomes the "beneficial owner" (as defined in Rules
     13d-3 and 13d-5 under the Exchange Act), directly or indirectly, of more
     than a majority of the voting power of all classes of Voting Stock of the
     Company;

          (2) the Company consolidates with, or merges with or into, another
     Person or conveys, transfers, leases or otherwise disposes of all or
     substantially all of its assets to any Person, or any Person consolidates
     with, or merges with or into, the Company, in any such event pursuant to a
     transaction in which the outstanding Voting Stock of the Company is
     converted into or exchanged for cash, securities or other property, other
     than any such transaction where (i) the outstanding Voting Stock of the
     Company is not converted or exchanged at all (except to the extent
     necessary to reflect a change in the jurisdiction of incorporation) or is
     converted into or exchanged for (A) Voting Stock (other than Disqualified
     Stock) of the surviving or transferee Person or (B) cash, securities and
     other property (other than Capital Stock described in the foregoing clause
     (A)) of the surviving or transferee Person in an amount that could be paid
     as a Restricted Payment pursuant to Section 2.6(b) of this First
     Supplemental Indenture (Section 4.7 of the Indenture) and (ii) immediately
     after such transaction, no "person" or "group" (as such terms are used in
     Sections 13(d) and 14(d) of the Exchange Act), other than the Principal
     Stockholders (or any of them), is the "beneficial owner" (as defined in
     Rules 13d-3 and 13d-5 under the Exchange Act), directly or indirectly, of
     more than a majority of the total outstanding Voting Stock of the surviving
     or transferee Person;

          (3) during any consecutive two-year period, individuals who at the
     beginning of such period constituted the Board of Directors (together with
     any new directors whose election to such Board of Directors, or whose
     nomination for election by the stockholders of the Company, was approved by
     a vote of 66 2/3% 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 Board of Directors then in office; or


                                       4



          (4) the Company is liquidated or dissolved or adopts a plan of
     liquidation or dissolution other than in a transaction which complies with
     Section 2.7 of the First Supplemental Indenture (Section 5.1 of the
     Indenture).

     "CONSOLIDATED ADJUSTED NET INCOME" means, for any period, the net income
(or net loss) of the Company and its Restricted Subsidiaries for such period as
determined on a consolidated basis in accordance with GAAP, adjusted to the
extent included in calculating such net income or loss by excluding:

          (1) any net after-tax extraordinary gains or losses (less all fees and
     expenses relating thereto);

          (2) any net after-tax gains or losses (less all fees and expenses
     relating thereto) attributable to Asset Sales;

          (3) the portion of net income (or loss) of any Person (other than the
     Company or a Restricted Subsidiary), including Unrestricted Subsidiaries,
     in which the Company or any Restricted Subsidiary has an ownership
     interest, except to the extent of the amount of dividends or other
     distributions actually paid to the Company or any Restricted Subsidiary in
     cash dividends or distributions by such Person during such period; and

          (4) the net income (or loss) of any Person combined with the Company
     or any Restricted Subsidiary on a "pooling of interests" basis attributable
     to any period prior to the date of combination.

     "CONSOLIDATED INCOME TAX EXPENSE" means, for any period, the provision for
federal, state, local and foreign income taxes of the Company and its Restricted
Subsidiaries for such period as determined on a consolidated basis in accordance
with GAAP.

     "CONSOLIDATED INTEREST EXPENSE" means, for any period, without duplication,
the sum of:

          (1) the amount which, in conformity with GAAP, would be set forth
     opposite the caption "interest expense" (or any like caption) on a
     consolidated statement of operations of the Company and its Restricted
     Subsidiaries for such period, including, without limitation:

               (i) amortization of debt discount;

               (ii) the net cost of interest rate contracts (including
          amortization of discounts);

               (iii) the interest portion of any deferred payment obligation;

               (iv) amortization of debt issuance costs; and



                                       5



               (v) the interest component of Capital Lease Obligations of the
          Company and its Restricted Subsidiaries; plus

          (2) all interest on any Indebtedness of any other Person guaranteed
     and paid by the Company or any of its Restricted Subsidiaries;

provided, however, that Consolidated Interest Expense will not include any gain
or loss from extinguishment of debt, including write-off of debt issuance costs.

     "CONSOLIDATED NON-CASH CHARGES" means, for any period, the aggregate
depreciation, amortization and other non-cash expenses of the Company and its
Restricted Subsidiaries (including without limitation any minority interest)
reducing Consolidated Adjusted Net Income for such period, determined on a
consolidated basis in accordance with GAAP (excluding any such non-cash charge
to the extent that it requires an accrual of or reserve for cash charges for any
future period).

     "CREDIT AGENT" means The Chase Manhattan Bank, in its capacity as
administrative agent for the lenders party to the Credit Agreement, and The
Chase Manhattan Bank Canada, in its capacity as Canadian administrative agent
for the lenders party to the Credit Agreement, or any successor or successors
party thereto.

     "CREDIT AGREEMENT" means that certain Fourth Amended and Restated Credit
Agreement dated as of August 14, 2000, as amended, among the Company, IM Canada,
the lenders party thereto and the Credit Agent, as further amended, restated,
supplemented, modified, renewed, refunded, increased, extended, replaced or
refinanced from time to time.

     "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.

     "DEFINITIVE NOTES" means Notes that are in the form of the Notes attached
hereto as Exhibit A, that do not include the information called for by Section
2.15 of the Indenture.

     "DESIGNATED SENIOR DEBT" means:

          (1) Senior Bank Debt and

          (2) other Senior Debt the principal amount of which is $50.0 million
     or more at the date of designation by the Company in a written instrument
     delivered to the Trustee.

Senior Debt designated as Designated Senior Debt pursuant to clause (2) shall
cease to be Designated Senior Debt at any time that the aggregate principal
amount thereof outstanding is $10.0 million or less.

     "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, for cash or other property (other than Capital Stock that is not
Disqualified Stock) pursuant to a sinking fund obligation or otherwise, or is
redeemable at the option of the Holder thereof, in whole or in part, in each
case on or prior to the stated maturity of the Notes.


                                       6



     "DOLLARS" and "$" mean lawful money of the United States of America.

     "EBITDA" means for any period Consolidated Adjusted Net Income for such
period increased by:

          (1) Consolidated Interest Expense for such period; plus

          (2) Consolidated Income Tax Expense for such period; plus

          (3) Consolidated Non-Cash Charges for such period.

     "EQUITY INTERESTS" means Capital Stock and all warrants, options or other
rights to acquire Capital Stock (but excluding any debt security that is
convertible into, or exchangeable for, Capital Stock).

     "EQUITY PROCEEDS" means:

          (1) with respect to Equity Interests (or debt securities converted
     into Equity Interests) issued or sold for cash Dollars, the aggregate
     amount of such cash Dollars and

          (2) with respect to Equity Interests (or debt securities converted
     into Equity Interests) issued or sold for any consideration other than cash
     Dollars, the aggregate Market Price thereof computed on the date of the
     issuance or sale thereof.

     "EXCLUDED RESTRICTED SUBSIDIARY" means any Restricted Subsidiary organized
under the laws of a jurisdiction other than the United States (as defined in
Regulation S under the Securities Act) and that has not delivered a Subsidiary
Guarantee.

     "EXISTING INDEBTEDNESS" means Indebtedness of the Company and its
Subsidiaries (other than under the Credit Agreement) in existence on the date of
the Indenture, until such amounts are repaid.

     "GLOBAL NOTE" means a permanent global Note that contains the paragraph
referred to in Section 2.15 of the Indenture and the additional Schedule of
Exchanges of Notes to the form of the Note attached hereto as Exhibit A, and
that is deposited with and registered in the name of the Depository.

     "GOVERNMENT SECURITIES" means direct obligations of, or obligations
guaranteed by, the United States of America for the payment of which guarantee
or obligations the full faith and credit of the United States of America is
pledged.

     "GUARANTEE" means, as applied to any obligation:

          (1) a guarantee (other than by endorsement of negotiable instruments
     for collection in the ordinary course of business), direct or indirect, in
     any manner, of any part or all of such obligation; and



                                       7




          (2) an agreement, direct or indirect, contingent or otherwise, the
     practical effect of which is to assure in any way the payment or
     performance (or payment of damages in the event of non-performance) of all
     or any part of such obligation, including, without limiting the foregoing,
     the obligation to reimburse amounts drawn down under letters of credit
     securing such obligations.

     "HEDGING OBLIGATIONS" means, with respect to any Person, the obligations of
such Person under:

          (1) interest rate swap agreements, interest rate cap agreements and
     interest rate collar agreements and

          (2) other agreements or arrangements designed to protect such Person
     against fluctuations in interest rates.

     "IM CANADA" means Iron Mountain Canada Corporation, a Wholly Owned
Subsidiary of the Company, formerly known as Pierce Leahy Canada Company.

     "INDEBTEDNESS" means (without duplication), with respect to any Person,
whether recourse is to all or a portion of the assets of such Person, and
whether or not contingent:

          (1) every obligation of such Person for money borrowed;

          (2) every obligation of such Person evidenced by bonds, debentures,
     notes or other similar instruments;

          (3) every reimbursement obligation of such Person with respect to
     letters of credit, bankers' acceptances or similar facilities issued for
     the account of such Person;

          (4) every obligation of such Person issued or assumed as the deferred
     purchase price of property or services;

          (5) every Capital Lease Obligation and every obligation of such Person
     in respect of Sale and Leaseback Transactions that would be required to be
     capitalized on the balance sheet in accordance with GAAP;

          (6) all Disqualified Stock of such Person valued at the greater of its
     voluntary or involuntary maximum fixed repurchase price, plus accrued and
     unpaid dividends (unless included in such maximum repurchase price);

          (7) all obligations of such Person under or with respect to Hedging
     Obligations which would be required to be reflected on the balance sheet as
     a liability of such Person in accordance with GAAP; and

          (8) every obligation of the type referred to in clauses (1) through
     (7) of another Person and dividends of another Person the payment of which,
     in either case, such Person has guaranteed.


                                       8



     For purposes of this definition, the "maximum fixed repurchase price" of
any Disqualified Stock that does not have a fixed repurchase price shall be
calculated in accordance with the terms of such Disqualified Stock as if such
Disqualified Stock were repurchased on any date on which Indebtedness is
required to be determined pursuant to the First Supplemental Indenture, and if
such price is based upon, or measured by, the fair market value of such
Disqualified Stock, such fair market value shall be determined in good faith by
the board of directors of the issuer of such Disqualified Stock. Notwithstanding
the foregoing, trade accounts payable and accrued liabilities arising in the
ordinary course of business and any liability for federal, state or local taxes
or other taxes owed by such Person shall not be considered Indebtedness for
purposes of this definition. The amount outstanding at any time of any
Indebtedness issued with original issue discount is the aggregate principal
amount at maturity of such Indebtedness, less the remaining unamortized portion
of the original issue discount of such Indebtedness at such time, as determined
in accordance with GAAP.

     "INITIAL NOTES" means the first $225,000,000 aggregate principal amount of
8 5/8% Senior Subordinated Notes due 2013 that are issued under the First
Supplemental Indenture, as amended or supplemented from time to time pursuant to
the Indenture.

     "INVESTMENTS" means, with respect to any Person, all investments by such
Person in other Persons (including Affiliates) in the forms of loans (including
Guarantees), advances or capital contributions (excluding commission, travel and
similar advances to officers and employees made in the ordinary course of
business), purchases or other acquisitions for consideration of Indebtedness,
Equity Interests or other securities and all other items that are or would be
classified as investments on a balance sheet prepared in accordance with GAAP.

     "LEVERAGE RATIO" means, at any date, the ratio of:

          (1) the aggregate principal amount of Indebtedness of the Company and
     its Restricted Subsidiaries outstanding as of the most recent available
     quarterly or annual balance sheet, to

          (2) Adjusted EBITDA, after giving pro forma effect, without
     duplication, to

               (i) the incurrence, repayment or retirement of any Indebtedness
          by the Company or its Restricted Subsidiaries since the last day of
          the most recent full fiscal quarter of the Company;

               (ii) if the Leverage Ratio is being determined in connection with
          the incurrence of Indebtedness by the Company or a Restricted
          Subsidiary, such Indebtedness; and

               (iii) the Indebtedness to be incurred in connection with the
          acquisition of any Acquisition EBITDA Entity.

     "LIEN" means, with respect to any asset, any mortgage, lien, pledge,
charge, security interest or encumbrance of any kind in respect of such asset,
whether or not filed, recorded or otherwise perfected under applicable law
(including any conditional sale or other title retention agreement, any lease in
the nature thereof, any option or other agreement to sell or give a security
interest in and any filing of or agreement to give any financing statement under
the Uniform Commercial Code, or equivalent statutes, of any jurisdiction).



                                       9




     "MAKE-WHOLE AMOUNT" means, with respect to any Note, an amount equal to the
excess, if any, of:


          (1) the present value of the remaining principal, premium and interest
     payments that would be payable with respect to such Note if such Note were
     redeemed on April 1, 2006, computed using a discount rate equal to the
     Treasury Rate plus 75 basis points over

          (2) the outstanding principal amount of such Note.

     "MAKE-WHOLE AVERAGE LIFE" means, with respect to any date of redemption of
Notes, the number of years (calculated to the nearest one-twelfth) from such
redemption date to April 1, 2006.

     "MAKE-WHOLE PRICE" means, with respect to any Note, the greater of:

          (1) the sum of the principal amount of and Make-Whole Amount with
     respect to such Note and

          (2) the redemption price of such Note on April 1, 2006.

     "MARKET PRICE" means:

          (1) with respect to the calculation of Equity Proceeds from the
     issuance or sale of debt securities which have been converted into Equity
     Interests, the value received upon the original issuance or sale of such
     converted debt securities, as determined reasonably and in good faith by
     the Board of Directors and

          (2) with respect to the calculation of Equity Proceeds from the
     issuance or sale of Equity Interests, the average of the daily closing
     prices for such Equity Interests for the 20 consecutive trading days
     preceding the date of such computation.

     The closing price for each day shall be:

          (1) if such Equity Interests are then listed or admitted to trading on
     the New York Stock Exchange, the closing price on the NYSE Consolidated
     Tape (or any successor consolidated tape reporting transactions on the New
     York Stock Exchange) or, if such composite tape shall not be in use or
     shall not report transactions in such Equity Interests, or if such Equity
     Interests shall be listed on a stock exchange other than the New York Stock
     Exchange (including for this purpose the Nasdaq National Market), the last
     reported sale price regular way for such day, or in case no such reported
     sale takes place on such day, the average of the closing bid and asked
     prices regular way for such day, in each case on the principal national
     securities exchange on which such Equity Interests are listed or admitted
     to trading (which shall be the national securities exchange on which the
     greatest number of such Equity Interests have been traded during such 20
     consecutive trading days); or



                                       10




          (2) if such Equity Interests are not listed or admitted to trading on
     any such exchange, the average of the closing bid and asked prices thereof
     in the over-the-counter market as reported by the National Association of
     Securities Dealers Automated Quotation System or any successor system, or
     if not included therein, the average of the closing bid and asked prices
     thereof furnished by two members of the National Association of Securities
     Dealers selected reasonably and in good faith by the Board of Directors for
     that purpose. In the absence of one or more such quotations, the Market
     Price for such Equity Interests shall be determined reasonably and in good
     faith by the Board of Directors.

     "NET PROCEEDS" means the aggregate cash proceeds received by the Company or
any of its Restricted Subsidiaries in respect of any Asset Sale, which amount is
equal to the excess, if any, of:

          (1) the cash received by the Company or such Restricted Subsidiary
     (including any cash payments received by way of deferred payment pursuant
     to, or monetization of, a note or installment receivable or otherwise, but
     only as and when received) in connection with such disposition, over

          (2) the sum of:

               (i) the amount of any Indebtedness which is secured by such asset
          and which is required to be repaid in connection with the disposition
          thereof; plus

               (ii) the reasonable out-of-pocket expenses incurred by the
          Company or such Restricted Subsidiary, as the case may be, in
          connection with such disposition or in connection with the transfer of
          such amount from such Restricted Subsidiary to the Company; plus

               (iii) provisions for taxes, including income taxes, attributable
          to the disposition of such asset or attributable to required
          prepayments or repayments of Indebtedness with the proceeds thereof;
          plus

               (iv) if the Company does not first receive a transfer of such
          amount from the relevant Restricted Subsidiary with respect to the
          disposition of an asset by such Restricted Subsidiary and such
          Restricted Subsidiary intends to make such transfer as soon as
          practicable, the out-of-pocket expenses and taxes that the Company
          reasonably estimates will be incurred by the Company or such
          Restricted Subsidiary in connection with such transfer at the time
          such transfer is expected to be received by the Company (including,
          without limitation, withholding taxes on the remittance of such
          amount).



                                       11



     "NOTES" has the meaning assigned to it in the preamble to this First
Supplemental Indenture. The Initial Notes and any Additional Notes shall be
treated as a single class for all purposes under this First Supplemental
Indenture and the Indenture.

     "OBLIGATIONS" means any principal, interest (including post-petition
interest, whether or not allowed as a claim in any proceeding), penalties, fees,
costs, expenses, indemnifications, reimbursements, damages and other liabilities
payable under or in connection with any Indebtedness.

     "OFFICERS' CERTIFICATE" means a certificate signed, unless otherwise
specified, by any two of the Chairman of the Board, a Vice Chairman of the
Board, the President, the Chief Financial Officer, the Controller, or an
Executive Vice President of the Company, and delivered to the Trustee.

     "PERMITTED INVESTMENTS" means:

          (1) any Investments in the Company or in a Restricted Subsidiary
     (other than an Excluded Restricted Subsidiary) of the Company, including
     without limitation the Guarantee of Indebtedness permitted under Section
     2.6(c) of the First Supplemental Indenture (Section 4.8 of the Indenture);

          (2) any Investments in Cash Equivalents;

          (3) Investments by the Company or any Restricted Subsidiary of the
     Company in a Person, if as a result of such Investment;

               (i) such Person becomes a Restricted Subsidiary (other than an
          Excluded Restricted Subsidiary) of the Company or

               (ii) such Person is merged, consolidated or amalgamated with or
          into, or transfers or conveys substantially all of its assets to, or
          is liquidated into, the Company or a Restricted Subsidiary (other than
          an Excluded Restricted Subsidiary) of the Company;

          (4) Investments in assets (including accounts and notes receivable)
     owned or used in the ordinary course of business;

          (5) Investments for any purpose related to the Company's records and
     information management business (including, without limitation, the
     Company's confidential destruction and fulfillment businesses) in an
     aggregate outstanding amount not to exceed $10.0 million; and

          (6) Investments by the Company or a Restricted Subsidiary (other than
     an Excluded Restricted Subsidiary) in one or more Excluded Restricted
     Subsidiaries, the aggregate outstanding amount of which does not exceed 10%
     of the consolidated assets of the Company and its Restricted Subsidiaries.

     "PERMITTED LIENS" means:

          (1) Liens existing as of the date hereof;


                                       12



          (2) Liens on property or assets of the Company or any Restricted
     Subsidiary securing Senior Debt;

          (3) Liens on any property or assets of a Restricted Subsidiary granted
     in favor of the Company or any Wholly Owned Restricted Subsidiary;

          (4) Liens securing the Notes or the Guarantees;

          (5) any interest or title of a lessor under any Capital Lease
     Obligation or Sale and Leaseback Transaction so long as the Indebtedness,
     if any, secured by such Lien does not exceed the principal amount of
     Indebtedness permitted under Section 2.6(c) of the First Supplemental
     Indenture (Section 4.8 of the Indenture);

          (6) Liens securing Acquired Debt created prior to (and not in
     connection with or in contemplation of) the incurrence of such Indebtedness
     by the Company or any Restricted Subsidiary; provided that such Lien does
     not extend to any property or assets of the Company or any Restricted
     Subsidiary other than the assets acquired in connection with the incurrence
     of such Acquired Debt;

          (7) Liens securing Hedging Obligations permitted to be incurred
     pursuant to clause (7) of Section 2.6(c) of the First Supplemental
     Indenture (clause (7) of Section 4.8 of the Indenture);

          (8) Liens arising from purchase money mortgages and purchase money
     security interests, or in respect of the construction of property or
     assets, incurred in the ordinary course of the business of the Company or a
     Restricted Subsidiary; provided that (i) the related Indebtedness is not
     secured by any property or assets of the Company or any Restricted
     Subsidiary other than the property and assets so acquired or constructed
     and (ii) the Lien securing such Indebtedness is created within 60 days of
     such acquisition or construction;

          (9) statutory Liens or landlords' and carriers', warehousemen's,
     mechanics', suppliers', materialmen's, repairmen's or other like Liens
     arising in the ordinary course of business and with respect to amounts not
     yet delinquent or being contested in good faith by appropriate proceedings,
     if a reserve or other appropriate provision, if any, as is then required in
     conformity with GAAP shall have been made therefor;

          (10) Liens for taxes, assessments, government charges or claims with
     respect to amounts not yet delinquent or that are being contested in good
     faith by appropriate proceedings diligently conducted, if a reserve or
     other appropriate provision, if any, as is required in conformity with GAAP
     has been made therefor;

          (11) Liens incurred or deposits made to secure the performance of
     tenders, bids, leases, statutory obligations, surety and appeal bonds,
     government contracts, performance bonds and other obligations of a like
     nature incurred in the ordinary course of business (other than contracts
     for the payment of money);



                                       13



          (12) easements, rights-of-way, restrictions and other similar charges
     or encumbrances not interfering in any material respect with the business
     of the Company or any Restricted Subsidiary incurred in the ordinary course
     of business;

          (13) Liens arising by reason of any judgment, decree or order of any
     court so long as such Lien is adequately bonded and any appropriate legal
     proceedings that may have been duly initiated for the review of such
     judgment, decree or order shall not have been finally terminated or the
     period within which such proceedings may be initiated shall not have
     expired;

          (14) Liens arising under options or agreements to sell assets;

          (15) other Liens securing obligations incurred in the ordinary course
     of business, which obligations do not exceed $10.0 million in the aggregate
     at any one time outstanding; and

          (16) any extension, renewal or replacement, in whole or in part, of
     any Lien described in the foregoing clauses (1) through (15); provided that
     any such extension, renewal or replacement shall not extend to any
     additional property or assets.

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

     "PRINCIPAL STOCKHOLDERS" means each of Vincent J. Ryan, Schooner Capital
LLC, C. Richard Reese, Kent P. Dauten, B. Thomas Golisano and their respective
Affiliates.

     "QUALIFIED EQUITY OFFERING" means an offering of Capital Stock, other than
Disqualified Stock, of the Company for Dollars, whether registered or exempt
from registration under the Securities Act.

     "QUALIFIED ISSUER" means:

          (1) any lender party to the Credit Agreement or

          (2) any commercial bank:

               (i) which has capital and surplus in excess of $500,000,000 and

               (ii) the outstanding short-term debt securities of which are
          rated at least A-2 by Standard & Poor's Rating Group, a division of
          McGraw-Hill, Inc. or at least P-2 by Moody's Investors Service, or
          carry an equivalent rating by a nationally recognized rating agency if
          both of the two named rating agencies cease publishing ratings of
          investments.

     "QUALIFYING SALE AND LEASEBACK TRANSACTION" means any Sale and Leaseback
Transaction between the Company or any of its Restricted Subsidiaries and any
bank, insurance company or other lender or investor providing for the leasing to
the Company or such Restricted Subsidiary of any



                                       14




property (real or personal) which has been or is to be sold or transferred by
the Company or such Restricted Subsidiary to such lender or investor or to any
Person to whom funds have been or are to be advanced by such lender or investor
and where the property in question has been constructed or acquired after the
date of the First Supplemental Indenture.

     "REFINANCING INDEBTEDNESS" means new Indebtedness incurred or given in
exchange for, or the proceeds of which are used to repay, redeem, defease,
extend, refinance, renew, replace or refund, other Indebtedness; provided,
however, that:

          (1) the principal amount of such new Indebtedness shall not exceed the
     principal amount of Indebtedness so repaid, redeemed, defeased, extended,
     refinanced, renewed, replaced or refunded (plus the amount of fees,
     premiums, consent fees, prepayment penalties and expenses incurred in
     connection therewith);

          (2) such Refinancing Indebtedness shall have a Weighted Average Life
     to Maturity equal to or greater than the Weighted Average Life to Maturity
     of the Indebtedness so repaid, redeemed, defeased, extended, refinanced,
     renewed, replaced or refunded or shall mature after the maturity date of
     the Notes;

          (3) to the extent such Refinancing Indebtedness refinances
     Indebtedness that has a final maturity date occurring after the initial
     scheduled maturity date of the Notes, such new Indebtedness shall have a
     final scheduled maturity not earlier than the final scheduled maturity of
     the Indebtedness so repaid, redeemed, defeased, extended, refinanced,
     renewed, replaced or refunded and shall not permit redemption at the option
     of the holder earlier than the earliest date of redemption at the option of
     the holder of the Indebtedness so repaid, redeemed, defeased, extended,
     refinanced, renewed, replaced or refunded;

          (4) to the extent such Refinancing Indebtedness refinances
     Indebtedness subordinate to the Notes, such Refinancing Indebtedness shall
     be subordinated in right of payment to the Notes and to the extent such
     Refinancing Indebtedness refinances Notes or Indebtedness PARI PASSU with
     the Notes, such Refinancing Indebtedness shall be PARI PASSU with or
     subordinated in right of payment to the Notes, in each case on terms at
     least as favorable to the holders of Notes as those contained in the
     documentation governing the Indebtedness so repaid, redeemed, defeased,
     extended, refinanced, renewed, replaced or refunded; and

          (5) with respect to Refinancing Indebtedness incurred by a Restricted
     Subsidiary, such Refinancing Indebtedness shall rank no more senior, and
     shall be at least as subordinated, in right of payment to the Subsidiary
     Guarantee of such Restricted Subsidiary as the Indebtedness being extended,
     refinanced, renewed, replaced or refunded.


                                       15




     "RESTRICTED SUBSIDIARY" means:

          (1) each direct or indirect Subsidiary of the Company existing on the
     date of the First Supplemental Indenture (other than Iron Mountain
     (Netherlands) B.V. and its subsidiaries (including Iron Mountain Europe
     Limited), Iron Mountain Cayman Ltd. and its subsidiaries, Iron Mountain
     Mexico, S.A. de R.L. de C.V., PLRH Inc. and Upper Providence Venture I,
     L.P.) and

          (2) any other direct or indirect Subsidiary of the Company formed,
     acquired or existing after the date of the First Supplemental Indenture
     (including an Excluded Restricted Subsidiary),

which, in the case of (1) or (2), is not designated by the Board of Directors as
an "Unrestricted Subsidiary."

     "SALE AND LEASEBACK TRANSACTION" means any transaction or series of related
transactions pursuant to which a Person sells or transfers any property or asset
in connection with the leasing, or the resale against installment payments, of
such property or asset to the seller or transferor.

     "SENIOR BANK DEBT" means all Obligations outstanding under or in connection
with the Credit Agreement (including Guarantees of such Obligations by
Subsidiaries of the Company).

     "SENIOR DEBT" means:

          (1) the Senior Bank Debt and

          (2) any other Indebtedness permitted to be incurred by the Company or
     any Restricted Subsidiary, as the case may be, under the terms of the First
     Supplemental Indenture or the Indenture, unless the instrument under which
     such Indebtedness is incurred expressly provides that it is:

               (i) on a parity with or subordinated in right of payment to the
          Notes or

               (ii) subordinated to Senior Debt on terms substantially similar
          to those of the Notes.

     Notwithstanding anything to the contrary in the foregoing, Senior Debt
shall not include:

          (1) any liability for federal, state, local or other taxes owed or
     owing by the Company;

          (2) any Indebtedness of the Company to any of its Subsidiaries or
     other Affiliates;

          (3) any trade payables; or

          (4) any Indebtedness that is incurred in violation of the First
     Supplemental Indenture or the Indenture, provided that such Indebtedness
     shall be deemed not to have been incurred in violation of the First
     Supplemental Indenture or the Indenture for purposes of this clause (4) if,
     in the case of any obligations under the Credit Agreement, the holders of
     such obligations or their agent or representative shall have received a
     representation from the Company to the effect that the incurrence of such
     Indebtedness does not violate the provisions of the First Supplemental
     Indenture or the Indenture.



                                       16




     "SIGNIFICANT SUBSIDIARY" means any Subsidiary that would be a "significant
subsidiary" as defined in Article 1, Rule 1-02 of Regulation S-X, promulgated
pursuant to the Securities Act, as such Regulation is in effect on the date
hereof.

     "SUBSIDIARY" means, with respect to any Person, 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 such
Person or one or more of the other Subsidiaries of such Person or a combination
thereof.

     "TREASURY RATE" means, at any time of computation, the yield to maturity at
such time (as compiled by and published in the most recent Federal Reserve
Statistical Release H.15(519), which has become publicly available at least two
business days prior to the date of the redemption notice or, if such Statistical
Release is no longer published, any publicly available source of similar market
data) of United States Treasury securities with a constant maturity most nearly
equal to the Make-Whole Average Life; provided, however, that if the Make-Whole
Average Life is not equal to the constant maturity of the United States Treasury
security for which a weekly average yield is given, the Treasury Rate shall be
obtained by linear interpolation (calculated to the nearest one-twelfth of a
year) from the weekly average yields of United States Treasury securities for
which such yields are given, except that if the Make-Whole Average Life is less
than one year, the weekly average yield on actually traded United States
Treasury securities adjusted to a constant maturity of one year shall be used.

     "UNRESTRICTED SUBSIDIARY" means:

          (1) any Subsidiary that is designated by the Board of Directors as an
     Unrestricted Subsidiary in accordance with Section 2.6(i) of the First
     Supplemental Indenture (Section 4.14 of the Indenture) and

          (2) any Subsidiary of an Unrestricted Subsidiary.

As of the date hereof, the following Subsidiaries of the Company have been
designated as Unrestricted Subsidiaries: Iron Mountain (Netherlands) B.V. and
its subsidiaries (including Iron Mountain Europe Limited), Iron Mountain Cayman
Ltd. and its subsidiaries, Iron Mountain Mexico, S.A. de R.L. de C.V., PLRH Inc.
and Upper Providence Venture I, L.P.

     "VOTING STOCK" means any class or classes of Capital Stock pursuant to
which the holders thereof have the general voting power under ordinary
circumstances to elect at least a majority of the board of directors, managers
or trustees of any Person (irrespective of whether or not, at the time, stock of
any other class or classes has, or might have, voting power by reason of the
happening of any contingency).



                                       17


     "WEIGHTED AVERAGE LIFE TO MATURITY" means, when applied to any Indebtedness
at any date, the number of years obtained by dividing:

          (1) the sum of the products obtained by multiplying (x) the amount of
     each then remaining installment, sinking fund, serial maturity or other
     required payment of principal, including payment at final maturity, in
     respect thereof, by (y) the number of years (calculated to the nearest
     one-twelfth) that will elapse between such date and the making of such
     payment, by

          (2) the then outstanding principal amount of such Indebtedness.

     "WHOLLY OWNED RESTRICTED SUBSIDIARY" means any Restricted Subsidiary of the
Company all of the outstanding Capital Stock or other ownership interests of
which (other than directors' qualifying shares) shall at the time be owned by
the Company or by one or more Wholly Owned Restricted Subsidiaries of the
Company.

     "1996 INDENTURE DATE" means October 1, 1996.

     "1999 INDENTURE DATE" means April 26, 1999.

     "8 1/8% NOTES" means IM Canada's 8 1/8% Senior Notes due 2008 issued
pursuant to the Indenture dated as of April 7, 1998, by and among IM Canada,
as issuer, the Company and The Bank of New York, as trustee. The 8 1/8% Notes
have been guaranteed by the Company and certain of its Subsidiaries
(including, without limitation, the Guarantors) on a senior subordinated
basis.

     "8 1/4% NOTES" means the Company's 8 1/4% Senior Subordinated Notes due
2011 issued pursuant to the Indenture dated April 26, 1999, by and among the
Company, certain of its subsidiaries and The Bank of New York, as trustee.

     "8 3/4% NOTES" means the Company's 8 3/4% Senior Subordinated Notes due
2009 issued pursuant to the Indenture dated October 24, 1997, by and among
the Company, certain of its subsidiaries and The Bank of New York, as trustee.

     "9 1/8% NOTES" means the Company's 9 1/8% Senior Subordinated Notes due
2007, issued pursuant to the Indenture dated as of July 7, 1997, by and
between the Company, as issuer, and The Bank of New York, as trustee.

     "10 1/8% NOTES" means the Company's 10 1/8% Senior Subordinated Notes
due 2006 issued pursuant to the Indenture dated October 1, 1996, by and among
the Company, certain of its subsidiaries and First Bank National Association,
as trustee.

     "11 1/8% NOTES" means the Company's 11 1/8% Senior Subordinated Notes
due 2006 issued pursuant to the Indenture dated as of July 15, 1996, between
the Company, as issuer, and United States Trust Company of New York, as
trustee.

                                       18




               (b) Other Definitions.

     The definitions of the following terms may be found in the Sections
indicated as follows:



     Term                                        Defined in Section
                                              
     "Affiliate Transaction"                     2.6(f)
     "Asset Sale"                                2.6(k)
     "Asset Sale Offer"                          2.6(k)
     "Bankruptcy Law"                            2.8
     "Change of Control Offer"                   2.6(l)
     "Change of Control Payment"                 2.6(l)
     "Change of Control Payment Date"            2.6(l)
     "Commencement Date"                         2.6(k)
     "Custodian"                                 2.8
     "DTC"                                       2.3
     "Event of Default"                          6.1
     "Excess Proceeds"                           2.6(k)
     "First Supplemental Indenture"              Preamble
     "incur"                                     2.6(c)
     "Indenture"                                 Preamble
     "Restricted Payments"                       2.6(b)




                                   ARTICLE 2.

                           FORM AND TERMS OF THE NOTES

     Section 2.1. FORM AND DATING.(a) GENERAL. The Notes and the Trustee's
certificate of authentication shall be substantially in the form of Exhibit A
attached hereto. The Notes may have notations, legends or endorsements required
by law, stock exchange rule or usage. 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 contained in the Notes shall constitute, and are
hereby expressly made, a part of the First Supplemental Indenture and the
Indenture and the Company, the Guarantors and the Trustee, by their execution
and delivery of the First Supplemental Indenture and the Indenture (or in the
case of any Guarantor that becomes such after the date hereof, a supplemental
indenture pursuant to Section 2.6(h) of this First Supplemental Indenture
(Section 4.13 of the Indenture)), expressly agree to such terms and provisions
and to be bound thereby.

     (b) GLOBAL NOTES. Notes shall be issued initially in the form of the Global
Notes, which shall be deposited on behalf of the purchasers of the Notes
represented thereby with the Depository at its New York office, and registered
in the name of the Depository or a nominee of the Depository, duly executed by
the Company and authenticated by the Trustee as hereinafter provided. The
aggregate principal amount of the Global Notes may from time to time be
increased or decreased by adjustments made on the records of the Trustee and the
Depository or its nominee as hereinafter provided.

     The Global Notes shall represent such of the outstanding Notes as shall be
specified therein and shall provide that it shall represent the aggregate amount
of outstanding Notes from time to time endorsed thereon and that the aggregate
amount of outstanding Notes represented thereby may from time to time be reduced
or increased, as appropriate, to reflect exchanges and redemptions. Any
endorsement of the Global Notes to reflect the amount of any increase or
decrease in the amount of outstanding Notes represented thereby shall be made by
the Trustee or the Service Agent, at the direction of the Trustee, in accordance
with instructions given by the Holder thereof as required by Section 2.4 of this
First Supplemental Indenture.



                                       19



     Except as set forth in Section 2.4 of this First Supplemental Indenture,
the Global Notes may be transferred, in whole and not in part, only to another
nominee of the Depository or to a successor of the Depository or its nominee.

     (c) BOOK-ENTRY PROVISIONS. This Section 2.1(c) shall apply only to the
Global Notes deposited with or on behalf of the Depository.

     The Company shall execute and the Trustee shall, in accordance with this
Section 2.1(c), authenticate and deliver the Global Notes that (i) shall be
registered in the name of the Depository or the nominee of the Depository and
(ii) shall be delivered by the Trustee to the Depository or pursuant to the
Depository's instructions or held by the Service Agent.

     Agent Members shall have no rights either under the First Supplemental
Indenture or the Indenture with respect to any Global Notes held on their behalf
by the Depository or by the Service Agent or under such Global Notes, and the
Depository may be treated by the Company, the Trustee and any agent of the
Company or the Trustee as the absolute owner of such Global Notes for all
purposes whatsoever.

     (d) DEFINITIVE NOTES. Notes issued in certificated form shall be
substantially in the form of Exhibit A attached hereto (but without including
the text referred to in Section 2.15.3 of the Indenture). Except as provided in
Section 2.4, owners of beneficial interests in the Global Notes will not be
entitled to receive physical delivery of certificated Securities.

Section 2.2. EXECUTION AND AUTHENTICATION.

     The Trustee shall, upon a written order of the Company signed by an
Officer, authenticate up to $225,000,000 aggregate principal amount of Initial
Notes and up to $275,000,000 of Additional Notes.

Section 2.3. DEPOSITORY AND PAYING AGENT FOR NOTES.

     The Company initially appoints The Depository Trust Company ("DTC") to act
as Depository with respect to the Global Notes. The Company initially appoints
the Trustee to act as the Registrar, Paying Agent and Service Agent with respect
to the Global Notes.

Section 2.4. TRANSFER AND EXCHANGE OF NOTES.

     (a) TRANSFER AND EXCHANGE OF BENEFICIAL INTERESTS IN GLOBAL NOTES. The
transfer and exchange of beneficial interests in the Global Notes shall be
effected through the Depository, in accordance with the First Supplemental
Indenture and the Indenture and the procedures of the Depository therefor.
Beneficial interests in the Global Notes may be transferred to Persons who take
delivery thereof in the form of a beneficial interest in the Global Notes.



                                       20




     (b) TRANSFER AND EXCHANGE OF DEFINITIVE NOTES. When Definitive Notes are
presented by a Holder to the Registrar with a request:

          (x) to register the transfer of the Definitive Notes; or

          (y) to exchange such Definitive Notes for an equal principal amount of
     Definitive Notes of other authorized denominations,

the Registrar shall register the transfer or make the exchange as requested if
its requirements for such transactions are met; PROVIDED, HOWEVER, that the
Definitive Notes presented or surrendered for register of transfer or exchange
shall be duly endorsed or accompanied by a written instruction of transfer in
form satisfactory to the Registrar duly executed by such Holder or by his
attorney, duly authorized in writing.

     (c) RESTRICTIONS ON TRANSFER AND EXCHANGE OF GLOBAL NOTES. Notwithstanding
any other provision of the First Supplemental Indenture or the Indenture (other
than the provisions set forth in subsection (d) of this Section 2.4), the Global
Notes may not be transferred as a whole except by the Depository to a nominee of
the Depository or by a nominee of the Depository to the Depository or another
nominee of the Depository or by the Depository or any such nominee to a
successor Depository or a nominee of such successor Depository.

     (d) AUTHENTICATION OF DEFINITIVE NOTES IN ABSENCE OF DEPOSITORY. If at any
time:

          (i) the Depository for the Notes notifies the Company that the
     Depository is unwilling or unable to continue as Depository for the Global
     Notes and a successor Depository for the Global Notes is not appointed by
     the Company within 90 days after delivery of such notice; or

          (ii) the Company at its sole discretion, notifies the Trustee in
     writing that it elects to cause the issuance of Definitive Notes under the
     First Supplemental Indenture and the Indenture,

then the Company shall execute, and the Trustee shall, upon receipt of an
authentication order in accordance with Section 2.2 hereof, authenticate and
deliver, Definitive Notes in an aggregate principal amount equal to the
principal amount of the Global Notes in exchange for such Global Notes.

     (e) CANCELLATION AND/OR ADJUSTMENT OF THE GLOBAL NOTES. At such time as all
beneficial interests in the Global Notes have been exchanged for Definitive
Notes, redeemed, repurchased or canceled, the Global Notes shall be returned to
or retained and canceled by the Trustee in accordance with Section 2.12 of the
Indenture. At any time prior to such cancellation, if any beneficial interest in
the Global Notes is exchanged for Definitive Notes, redeemed, repurchased or
canceled, the aggregate principal amount of Notes represented by the Global
Notes shall be reduced accordingly and an endorsement shall be made on the
Global Notes, by the Trustee or the Service Agent, at the direction of the
Trustee, to reflect such reduction. A Definitive Note may be exchanged for a
beneficial interest in the Global Note only upon receipt by the Trustee of a
Definitive Note, duly endorsed or accompanied by appropriate instruments of
transfer, in form satisfactory to the Trustee, together with written
instructions directing the Trustee to make an endorsement on the Global Note to
reflect an increase in the aggregate principal amount of the Notes represented
by the



                                       21



Global Note; in which case the Trustee shall cancel such Definitive Note and
cause the aggregate principal amount of Notes represented by the Global Note to
be increased accordingly. If no Global Note is then outstanding, the Company
shall issue and the Trustee shall authenticate a new Global Note in the
appropriate principal amount.

     (f) GENERAL PROVISIONS RELATING TO TRANSFERS AND EXCHANGES.

          (i) To permit registrations of transfers and exchanges, the Company
     shall execute and the Trustee shall authenticate Definitive Notes and the
     Global Notes at the Registrar's request.

          (ii) No service charge shall be made to a Holder for any registration
     of transfer or exchange, 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 taxes or similar
     governmental charge payable upon exchange or transfer pursuant to Section
     2.4 of this First Supplemental Indenture).

          (iii) All Definitive Notes and the Global Notes issued upon any
     registration of transfer or exchange of Definitive Notes or the Global
     Notes shall be the valid obligations of the Company, evidencing the same
     debt, and entitled to the same benefits under the First Supplemental
     Indenture and the Indenture, as the Definitive Notes or the Global Notes
     surrendered upon such registration of transfer or exchange.

          (iv) Prior to due presentment for the registration of a transfer of
     any Note, the Trustee, any Agent, the Company and any Guarantor may deem
     and treat the Person in whose name any Note is registered as the absolute
     owner of such Note for all purposes, including receiving payment of
     principal of and interest on such Notes, and neither the Trustee, any
     Agent, the Company nor any Guarantor shall be affected by notice to the
     contrary.

          (v) The Trustee shall authenticate Definitive Notes and the Global
     Notes in accordance with the provisions of Section 2.2 of the First
     Supplemental Indenture and Section 2.3 of the Indenture.

Section 2.5. REDEMPTION.

     With respect to the Notes issued under this First Supplemental Indenture,
the following Sections supplement Article III of the Indenture:

     ss. 3.7. OPTIONAL REDEMPTION.

     Prior to April 1, 2006, the Notes shall be subject to redemption at any
time at the option of the Company, in whole or in part, upon not less than 30
nor more than 60 days' notice, at the Make-Whole Price, plus accrued and unpaid
interest, to but excluding the applicable redemption date. On and after April 1,
2006, the Notes will be subject to redemption at any time at the option of the
Company, in



                                       22



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) set forth
below, plus accrued and unpaid interest, to but excluding the applicable
redemption date, if redeemed during the twelve-month period beginning on April 1
of the years indicated below:



YEAR                                                               PERCENTAGE
                                                                
2006..........................................................       104.313%
2007..........................................................       102.875%
2008..........................................................       101.438%
2009 and thereafter...........................................       100.000%



     Notwithstanding the foregoing, at any time prior to April 1, 2004, the
Company may redeem up to 35% of the initial principal amount of the Notes
originally issued with the net proceeds of one or more Qualified Equity
Offerings at a redemption price equal to 108.625% of the principal amount of
such Notes, plus accrued and unpaid interest to but excluding the redemption
date; provided, that at least 65% of the principal amount of Notes originally
issued remains outstanding immediately after the occurrence of any such
redemption and that such redemption occurs within 60 days following the closing
of any such Qualified Equity Offering.

     ss. 3.8. MANDATORY REDEMPTION.

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

     ss. 3.9. ASSET SALE OFFERS.

     In the event that the Company shall commence an Asset Sale Offer pursuant
to Section 4.16 hereof, it shall follow the procedures specified below:

     The Asset Sale Offer shall remain open for 20 Business Days after the
Commencement Date relating to such Asset Sale Offer, except to the extent
required to be extended by applicable law (as so extended, the "OFFER PERIOD").
No later than one Business Day after the termination of the Offer Period (the
"PURCHASE DATE"), the Company shall purchase the principal amount (the "OFFER
AMOUNT") of Notes required to be purchased in such Asset Sale Offer pursuant to
Sections 3.2 and 4.16 hereof or, if less than the Offer Amount has been
tendered, all Notes tendered in response to the Asset Sale Offer.

     If the Purchase Date is on or after an interest payment record date and on
or before the related interest payment date, any interest accrued to such
Purchase Date 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 shall be
payable to Holders who tender Notes pursuant to the Asset Sale Offer.

     On the Commencement Date of any Asset Sale Offer, the Company shall send or
cause to be sent, by first class mail, a notice to each of the Holders, with a
copy to the Trustee. Such notice, which shall govern the terms of the Asset Sale
Offer, shall contain all instructions and materials necessary to enable the
Holders to tender Notes pursuant to the Asset Sale Offer and shall state:



                                       23




          (1) that the Asset Sale Offer is being made pursuant to this Section
     3.9 and Section 4.16 hereof and the length of time the Asset Sale Offer
     shall remain open;

          (2) the Offer Amount, the purchase price and the Purchase Date;

          (3) that any Note not tendered or accepted for payment shall continue
     to accrue interest;

          (4) that, unless the Company defaults in the payment of the purchase
     price, any Note accepted for payment pursuant to the Asset Sale Offer shall
     cease to accrue interest after the Purchase Date;

          (5) that Holders electing to have a Note purchased pursuant to any
     Asset Sale Offer shall 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 Business Day preceding the Purchase Date;

          (6) that Holders shall 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 Business Day preceding the
     termination of the Offer Period, a facsimile transmission or letter setting
     forth the name of the Holder, the principal amount of the Note the Holder
     delivered for purchase and a statement that such Holder is withdrawing
     such Holder's election to have the Note purchased;

          (7) that, if the aggregate principal amount of Notes surrendered by
     Holders exceeds the Offer Amount, the Trustee shall select the Notes to be
     purchased on a PRO RATA basis (with such adjustments as may be deemed
     appropriate by the Company so that only Notes in denominations of $1,000,
     or integral multiples thereof, shall be purchased); and

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

     On or before 12:00 noon on each Purchase Date, the Company shall
irrevocably deposit with the Trustee or Paying Agent in immediately available
funds the aggregate purchase price with respect to a principal amount of Notes
equal to the Offer Amount, together with accrued interest thereon, to be held
for payment in accordance with the terms of this Section 3.9. On the Purchase
Date, the Company shall, to the extent lawful, (i) accept for payment, on a PRO
RATA basis to the extent necessary, an aggregate principal amount equal to the
Offer Amount of Notes and other notes (in accordance with the terms of Section
4.16 of the Indenture) tendered pursuant to the Asset Sale Offer, or if less
than the Offer Amount has been tendered, all Notes and such other notes or
portions thereof tendered, (ii) deliver or cause the Paying Agent or depositary,
as the case may be, to deliver to the Trustee Notes so accepted and (iii)
deliver to the Trustee an Officers' Certificate stating that such Notes or
portions thereof were accepted for payment by the Company in accordance with the
terms of this Section 3.9. The Company, depositary or Paying Agent, as the case
may be, shall promptly (but in any case not later than three



                                       24



Business Days after the Purchase Date) mail or deliver to each tendering Holder
an amount equal to the purchase price with respect to the Notes tendered by such
Holder and accepted by the Company for purchase, and the Company shall promptly
issue a new Note, and the Trustee shall authenticate and mail or deliver such
new Note, to such Holder, equal in principal amount to any unpurchased portion
of such Holder's Notes surrendered. Any Note not accepted in the Asset Sale
Offer shall be promptly mailed or delivered by the Company to the Holder
thereof. The Company shall publicly announce in a newspaper of general
circulation the results of the Asset Sale Offer on the Purchase Date.

     The Asset Sale Offer shall be made by the Company in compliance with all
applicable laws, including, without limitation, Regulation 14E of the Exchange
Act and the rules thereunder, to the extent applicable, and all other applicable
federal and state securities laws.

     Each purchase pursuant to this Section 3.9 shall be made pursuant to the
provisions of the second paragraph of Section 3.5 hereof to the extent
applicable.

     In the event the amount of Excess Proceeds to be applied to an Asset Sale
Offer would result in the purchase of a principal amount of Notes which is not
evenly divisible by $1,000, the Trustee shall promptly refund to the Company the
portion of such Excess Proceeds that is not necessary to purchase the
immediately lesser principal amount of Notes that is so divisible.

Section 2.6. COVENANTS.

     With respect to the Notes issued under this First Supplemental Indenture,
Section (a) below replaces Section 4.2 of the Indenture, Section (m) below
replaces Section 4.5 of the Indenture and each other Section is added to Article
IV of the Indenture.

     (a) REPORTS.

     ss.4.2. REPORTS. Whether or not required by the rules and regulations of
the SEC, so long as any Notes are outstanding, the Company will furnish to
the Holders of Notes:

          (1) all quarterly and annual financial information that would be
     required to be contained in a filing with the SEC on Forms 10-Q and 10-K if
     the Company were required to file such Forms, including a "Management's
     Discussion and Analysis of Financial Condition and Results of Operations"
     and, with respect to the annual information only, a report thereon by the
     Company's certified independent accountants and

          (2) all financial information that would be required to be included in
     a Form 8-K filed with the SEC if the Company were required to file such
     reports.

In addition, whether or not required by the rules and regulations of the SEC,
the Company will file a copy of all such information and reports with the SEC
for public availability (unless the SEC will not accept such a filing) and make
such information available to investors who request it in writing.

(b) RESTRICTED PAYMENTS.



                                       25


     ss.4.7. RESTRICTED PAYMENTS. The Company shall not, and shall not permit
any of its Restricted Subsidiaries to, directly or indirectly:

          (1) declare or pay any dividend or make any distribution on account of
     the Company's or any of its Restricted Subsidiaries' Equity Interests
     (other than dividends or distributions payable in Equity Interests (other
     than Disqualified Stock) of the Company or such Restricted Subsidiary or
     dividends or distributions payable to the Company or any Restricted
     Subsidiary);

          (2) purchase, redeem or otherwise acquire or retire for value any
     Equity Interests of the Company or any Restricted Subsidiary or other
     Affiliate of the Company (other than any such Equity Interests owned by the
     Company or any Restricted Subsidiary);

          (3) purchase, redeem or otherwise acquire or retire prior to scheduled
     maturity for value any Indebtedness that is subordinated in right of
     payment to the Notes; or

          (4) make any Investment other than a Permitted Investment (all such
     payments and other actions set forth in clauses (1) through (4) above being
     collectively referred to as "RESTRICTED PAYMENTS");

unless, at the time of such Restricted Payment:

               (i) no Default or Event of Default shall have occurred and be
          continuing or would occur as a consequence thereof; and

               (ii) the Company would, at the time of such Restricted Payment
          and after giving pro forma effect thereto, have been permitted to
          incur at least $1.00 of additional Indebtedness pursuant to the test
          set forth in the first paragraph of Section 4.8 of the Indenture; and

               (iii) such Restricted Payment, together with the aggregate of all
          other Restricted Payments made by the Company and its Restricted
          Subsidiaries after the 1996 Indenture Date is less than (x) the
          cumulative EBITDA of the Company, minus 1.75 times the cumulative
          Consolidated Interest Expense of the Company, in each case for the
          period (taken as one accounting period) from June 30, 1996, to the end
          of the Company's most recently ended fiscal quarter for which internal
          financial statements are available at the time of such Restricted
          Payment, plus (y) the aggregate net Equity Proceeds received by the
          Company from the issuance or sale since the 1996 Indenture Date of
          Equity Interests of the Company or of debt securities of the Company
          that have been converted into such Equity Interests (other than Equity
          Interests or convertible debt securities sold to a Restricted
          Subsidiary of the Company and other than Disqualified Stock or debt
          securities that have been converted into Disqualified Stock), plus (z)
          $2.0 million.



                                       26




     The foregoing provisions will not prohibit:

          (1) the payment of any dividend within 60 days after the date of
     declaration thereof, if at said date of declaration such payment would have
     complied with the provisions of the Indenture;

          (2) the redemption, repurchase, retirement or other acquisition or
     retirement for value of any Equity Interests of the Company in exchange
     for, or with the net cash proceeds of, the substantially concurrent sale
     (other than to a Restricted Subsidiary of the Company) of other Equity
     Interests of the Company (other than any Disqualified Stock);

          (3) the defeasance, redemption, repurchase, retirement or other
     acquisition or retirement for value of Indebtedness that is subordinated in
     right of payment to the Notes in exchange for, or with the net cash
     proceeds of, a substantially concurrent issuance and sale (other than to a
     Restricted Subsidiary of the Company) of Equity Interests of the Company
     (other than Disqualified Stock);

          (4) the defeasance, redemption, repurchase, retirement or other
     acquisition or retirement for value of Indebtedness that is subordinated in
     right of payment to the Notes in exchange for, or with the net cash
     proceeds of, a substantially concurrent issue and sale (other than to the
     Company or any of its Restricted Subsidiaries) of Refinancing Indebtedness;

          (5) the repurchase of any Indebtedness subordinated in right of
     payment to the Notes at a purchase price not greater than 101% of the
     principal amount of such Indebtedness in the event of a Change of Control
     in accordance with provisions similar to the covenant set forth in Section
     2.6(l) of the First Supplemental Indenture (Section 4.17 of the Indenture),
     provided that prior to or contemporaneously with such repurchase the
     Company has made the Change of Control Offer as provided in such covenant
     with respect to the Notes and has repurchased all Notes validly tendered
     for payment in connection with such Change of Control Offer; and

          (6) additional payments to current or former employees or directors of
     the Company for repurchases of stock, stock options or other equity
     interests, provided that the aggregate amount of all such payments under
     this clause (6) does not exceed $0.5 million in any year and $2.0 million
     in the aggregate.

     The Restricted Payments described in clauses (2), (3), (5) and (6) of the
immediately preceding paragraph will be Restricted Payments that shall be
permitted to be taken in accordance with such paragraph but shall reduce the
amount that would otherwise be available for Restricted Payments under clause
(iii) of the first paragraph of this Section, and the Restricted Payments
described in clauses (1) and (4) of the immediately preceding paragraph shall be
Restricted Payments that shall be permitted to be taken in accordance with such
paragraph and shall not reduce the amount that would otherwise be available for
Restricted Payments under clause (iii) of the first paragraph of this Section.



                                       27




     If an Investment results in the making of a Restricted Payment, the
aggregate amount of all Restricted Payments deemed to have been made as
calculated under the foregoing provision shall be reduced by the amount of any
net reduction in such Investment (resulting from the payment of interest or
dividends, loan repayment, transfer of assets or otherwise) to the extent such
net reduction is not included in the Company's EBITDA; PROVIDED, HOWEVER, that
the total amount by which the aggregate amount of all Restricted Payments may be
reduced may not exceed the lesser of (a) the cash proceeds received by the
Company and its Restricted Subsidiaries in connection with such net reduction
and (b) the initial amount of such Investment.

     If the aggregate amount of all Restricted Payments calculated under the
foregoing provision includes an Investment in an Unrestricted Subsidiary or
other Person that thereafter becomes a Restricted Subsidiary, such Investment
will no longer be counted as a Restricted Payment for purposes of calculating
the aggregate amount of Restricted Payments. For the purpose of making any
calculations under the Indenture:

          (1) an Investment will include the fair market value of the net assets
     of any Restricted Subsidiary at the time that such Restricted Subsidiary is
     designated an Unrestricted Subsidiary and will exclude the fair market
     value of the net assets of any Unrestricted Subsidiary that is designated
     as a Restricted Subsidiary;

          (2) any property transferred to or from an Unrestricted Subsidiary
     will be valued at fair market value at the time of such transfer, provided
     that, in each case, the fair market value of an asset or property is as
     determined by the Board of Directors in good faith and

          (3) subject to the foregoing, the amount of any Restricted Payment, if
     other than cash, will be determined by the Board of Directors, whose good
     faith determination will be conclusive.

     The Board of Directors may designate a Restricted Subsidiary to be an
Unrestricted Subsidiary in compliance with the Section 4.14 of the Indenture.
Upon such designation, all outstanding Investments by the Company and its
Restricted Subsidiaries (except to the extent repaid in cash) in the Subsidiary
so designated will be deemed to be Restricted Payments made at the time of such
designation and will reduce the amount available for Restricted Payments under
the first paragraph of this covenant. Such designation will only be permitted if
such Restricted Payment would be permitted at such time and if such Restricted
Subsidiary otherwise meets the definition of an Unrestricted Subsidiary.

     (c) INCURRENCE OF INDEBTEDNESS AND ISSUANCE OF PREFERRED STOCK.

     ss.4.8. INCURRENCE OF INDEBTEDNESS AND ISSUANCE OF PREFERRED STOCK. The
Company shall not, and shall not permit any of its Restricted Subsidiaries to,
directly or indirectly, create, incur, issue, assume, guaranty or otherwise
become directly or indirectly liable with respect to (collectively, "INCUR") any
Indebtedness (including Acquired Debt) and the Company shall not permit any of
its Restricted Subsidiaries to issue any shares of preferred stock; provided,
however, that the Company may incur Indebtedness and may permit a Restricted
Subsidiary to incur Indebtedness if at the time of such incurrence and after
giving effect thereto the Leverage Ratio would be less than 6.5 to 1.0.



                                       28




     The foregoing limitations shall not apply to:

          (1) the incurrence by the Company or any Restricted Subsidiary of
     Senior Bank Debt in an aggregate amount not to exceed $100.0 million at any
     one time outstanding;

          (2) the issuance by the Restricted Subsidiaries of Subsidiary
     Guarantees;

          (3) the incurrence by the Company and its Restricted Subsidiaries of
     the Existing Indebtedness;

          (4) the issuance by the Company of the Notes;

          (5) the incurrence by the Company and its Restricted Subsidiaries of
     Capital Lease Obligations and/or additional Indebtedness constituting
     purchase money obligations up to an aggregate of $5.0 million at any one
     time outstanding, provided that the Liens securing such Indebtedness
     constitute Permitted Liens;

          (6) the incurrence of Indebtedness between (i) the Company and its
     Restricted Subsidiaries and (ii) the Restricted Subsidiaries;

          (7) Hedging Obligations that are incurred for the purpose of fixing or
     hedging interest rate risk with respect to any floating rate Indebtedness
     that is permitted by the terms of the Indenture to be outstanding;

          (8) the incurrence by the Company and its Restricted Subsidiaries of
     Indebtedness arising out of letters of credit, performance bonds, surety
     bonds and bankers' acceptances incurred in the ordinary course of business
     up to an aggregate of $5.0 million at any one time outstanding;

          (9) the incurrence by the Company and its Restricted Subsidiaries of
     Indebtedness consisting of guarantees, indemnities or obligations in
     respect of purchase price adjustments in connection with the acquisition or
     disposition of assets, including, without limitation, shares of Capital
     Stock; and

          (10) the incurrence by the Company and its Restricted Subsidiaries of
     Refinancing Indebtedness issued in exchange for, or the proceeds of which
     are used to repay, redeem, defease, extend, refinance, renew, replace or
     refund, Indebtedness referred to in clauses (2) through (5) above, and this
     clause (10) or that was otherwise permitted to be incurred pursuant to the
     test set forth in the first paragraph of this Section 4.8.

     (d) LIENS.

     ss.4.9. LIENS. Neither the Company nor any of its Restricted Subsidiaries
may directly or indirectly create, incur, assume or suffer to exist any Lien
(other than a Permitted Lien) upon any property or assets now owned or hereafter
acquired, or any income, profits or proceeds therefrom, or assign or otherwise
convey any right to receive income therefrom, unless (a) in the case of any Lien
securing any Indebtedness that is subordinate to the Notes, the Notes are
secured by a Lien on such property, assets or proceeds that is senior in
priority to such Lien and (b) in the case of any other Lien, the Notes are
equally and ratably secured with the obligation or liability secured by such
Lien.



                                       29




     (e) DIVIDEND AND OTHER PAYMENT RESTRICTIONS AFFECTING RESTRICTED
     SUBSIDIARIES.

     ss.4.10. DIVIDEND AND OTHER PAYMENT RESTRICTIONS AFFECTING RESTRICTED
SUBSIDIARIES. The Company shall not, and shall not permit any of its Restricted
Subsidiaries to, directly or indirectly, create or otherwise cause or suffer to
exist or become effective any encumbrance or restriction on the ability of any
Restricted Subsidiary to:

          (1) (i) pay dividends or make any other distributions to the Company
     or any of its Restricted Subsidiaries (A) on its Capital Stock or (B) with
     respect to any other interest or participation in, or measured by, its
     profits, or (ii) pay any Indebtedness owed to the Company or any of its
     Restricted Subsidiaries;

          (2) make loans or advances to the Company or any of its Restricted
     Subsidiaries; or

          (3) transfer any of its properties or assets to the Company or any of
     its Restricted Subsidiaries.

     However, the preceding restrictions will not apply to encumbrances or
restrictions existing under or by reason of:

          (1) Existing Indebtedness;

          (2) the Credit Agreement as in effect as of the date of the Indenture,
     and any amendments, modifications, restatements, renewals, increases,
     supplements, refundings, replacements or refinancing thereof, provided that
     such amendments, modifications, restatements, renewals, increases,
     supplements, refundings, replacements or refinancings are no more
     restrictive in the aggregate with respect to such dividend and other
     payment restrictions than those contained in the Credit Agreement as in
     effect on the date of the Indenture;

          (3) the Indenture and the Notes;

          (4) applicable law;

          (5) any instrument governing Indebtedness or Capital Stock of a Person
     acquired by the Company or any of its Restricted Subsidiaries as in effect
     at the time of such acquisition (except to the extent such Indebtedness was
     incurred in connection with or in contemplation of such acquisition), which
     encumbrance or restriction is not applicable to any Person, or the
     properties or assets of any Person, other than the Person, or the property
     or assets of the Person, so acquired, provided that the EBITDA of such
     Person is not taken into account in determining whether such acquisition
     was permitted by the terms of the Indenture;

          (6) customary non-assignment provisions in leases entered into in the
     ordinary course of business and consistent with past practices;



                                       30




          (7) restrictions on the transfer of property subject to purchase money
     obligations or Capital Lease Obligations otherwise permitted by clause (5)
     of Section 4.8 of the Indenture;

          (8) permitted Refinancing Indebtedness, provided that the restrictions
     contained in the agreements governing such Refinancing Indebtedness are no
     more restrictive in the aggregate than those contained in the agreements
     governing the Indebtedness being refinanced; or

          (9) any agreement or instrument governing Indebtedness of an Excluded
     Restricted Subsidiary provided that (i) at the time such agreement or
     instrument is entered into, such Excluded Restricted Subsidiary and its
     Restricted Subsidiaries have a Leverage Ratio of less than 6.5 to 1.0 and
     (ii) neither such Excluded Restricted Subsidiary nor any of its Restricted
     Subsidiaries shall, directly or indirectly, incur any Indebtedness
     (including Acquired Debt) unless at the time of such incurrence and after
     giving effect thereto, the Leverage Ratio for such Excluded Restricted
     Subsidiary and its Restricted Subsidiaries would be less than 6.5 to 1.0.
     For purposes of determining the Leverage Ratio under this clause (9) only,
     all references to the "Company" and its "Restricted Subsidiaries" or
     similar references in the definition of "Leverage Ratio" and other defined
     terms necessary to determine the Leverage Ratio shall be deemed to refer to
     such Excluded Restricted Subsidiary and its Restricted Subsidiaries,
     respectively.

     (f) TRANSACTIONS WITH AFFILIATES.

     ss.4.11. TRANSACTIONS WITH AFFILIATES. The Company shall not, and shall not
permit any of its Restricted Subsidiaries to, sell, lease, transfer or otherwise
dispose of any of its properties or assets to, or purchase any property or
assets from, or enter into any contract, agreement, understanding, loan, advance
or guarantee with, or for the benefit of, any Affiliate (each of the foregoing,
an "AFFILIATE TRANSACTION"), unless:

          (a) such Affiliate Transaction is on terms that are no less favorable
     to the Company or the relevant Restricted Subsidiary than those that would
     have been obtained in a comparable transaction by the Company or such
     Restricted Subsidiary with a non-Affiliated Person and

          (b) the Company delivers to the Trustee:

               (i) with respect to any Affiliate Transaction involving aggregate
          payments in excess of $5.0 million, a resolution of the Board of
          Directors set forth in an Officers' Certificate certifying that such
          Affiliate Transaction complies with clause (a) above and such
          Affiliate Transaction is approved by a majority of the disinterested
          members of the Board of Directors and

               (ii) with respect to any Affiliate Transaction involving
          aggregate payments in excess of $10.0 million, an opinion as to the
          fairness to the Company or such Restricted Subsidiary from a financial
          point of view issued by an investment banking firm of national
          standing.



                                       31




     The following items shall not be deemed Affiliate Transactions and
therefore, will not be subject to the provisions of the prior paragraph:

          (1) any employment agreement entered into by the Company or any of its
     Restricted Subsidiaries in the ordinary course of business and consistent
     with the past practice of the Company or such Restricted Subsidiary;

          (2) transactions between or among the Company and/or its Restricted
     Subsidiaries;

          (3) transactions permitted by the provisions of Section 4.7 of the
     Indenture; and

          (4) the grant of stock, stock options or other equity interests to
     employees and directors of the Company and any Restricted Subsidiary in
     accordance with duly adopted Company stock grant, stock option and similar
     plans.

     The provisions set forth in clause (b) above shall not apply to sales of
inventory by the Company or any Restricted Subsidiary to any Affiliate in the
ordinary course of business. The provisions of clause (b) (ii) above shall not
apply to loans or advances to the Company or any Restricted Subsidiary from, or
equity investments in the Company or any Restricted Subsidiary by, any Affiliate
to the extent permitted by the provisions of Section 4.8 of the Indenture.

     (g) CERTAIN SENIOR SUBORDINATED DEBT.

     ss.4.12. CERTAIN SENIOR SUBORDINATED DEBT. The Company shall not incur any
Indebtedness that is subordinated or junior in right of payment to any Senior
Debt of the Company and senior in any respect in right of payment to the Notes.
The Company shall not permit any Restricted Subsidiary to incur any Indebtedness
that is subordinated or junior in right of payment to its Senior Debt and senior
in any respect in right of payment to its Subsidiary Guarantee.

     (h) ADDITIONAL SUBSIDIARY GUARANTEES.

     ss.4.13. ADDITIONAL SUBSIDIARY GUARANTEES. If any entity (other than an
Excluded Restricted Subsidiary) shall become a Restricted Subsidiary after
the date of the First Supplemental Indenture, then such Restricted Subsidiary
shall execute a supplemental indenture in the form of Exhibit B attached
hereto, pursuant to which it shall provide a Subsidiary Guarantee, and
deliver an Opinion of Counsel with respect thereto, in accordance with the
terms of the Indenture.

     No Restricted Subsidiary (including any Excluded Restricted Subsidiary)
shall consolidate with or merge with or into (whether or not such Restricted
Subsidiary is the surviving Person), another Person (other than the Company)
whether or not affiliated with such Restricted Subsidiary unless:

          (1) subject to the provisions of the immediately following sentence,
     the Person formed by or surviving any such consolidation or merger (if
     other than such Restricted



                                       32




     Subsidiary) assumes all the obligations of such Restricted Subsidiary under
     its Subsidiary Guarantee (except in the case of an Excluded Restricted
     Subsidiary) pursuant to a supplemental indenture in form and substance
     reasonably satisfactory to the Trustee;

          (2) immediately after giving effect to such transaction, no Default or
     Event of Default exists; and

          (3) such Restricted Subsidiary, or any Person formed by or surviving
     any such consolidation or merger, would be permitted to incur, immediately
     after giving effect to such transaction, at least $1.00 of additional
     Indebtedness pursuant to the test set forth in the first paragraph of
     Section 4.8 of the Indenture.

In the event of:

          (1) a sale or other disposition of all of the assets of any Restricted
     Subsidiary, by way of merger, consolidation or otherwise;

          (2) a sale or other disposition of all of the capital stock of any
     Restricted Subsidiary; or

          (3) the designation of a Restricted Subsidiary as an Unrestricted
     Subsidiary in accordance with the terms of Section 4.14 of the Indenture,

then such Subsidiary (in the event of a sale or other disposition, by way of
such a merger, consolidation or otherwise, of all of the capital stock of such
Restricted Subsidiary or in the event of the designation of such Restricted
Subsidiary as an Unrestricted Subsidiary) or the Person acquiring the property
(in the event of a sale or other disposition of all of the assets of such
Restricted Subsidiary) will be released and relieved of any obligations under
its Subsidiary Guarantee, provided that the Net Proceeds of such sale or other
disposition are applied in accordance with the applicable provisions of Section
4.16 of the Indenture.

     (i) DESIGNATION OF UNRESTRICTED SUBSIDIARIES.

     ss.4.14. DESIGNATION OF UNRESTRICTED SUBSIDIARIES. The Board of Directors
may designate any Subsidiary (including any Restricted Subsidiary or any newly
acquired or newly formed Subsidiary) to be an Unrestricted Subsidiary so long
as:

          (1) neither the Company nor any Restricted Subsidiary is directly or
     indirectly liable for any Indebtedness of such Subsidiary;

          (2) no default with respect to any Indebtedness of such Subsidiary
     would permit (upon notice, lapse of time or otherwise) any holder of any
     other Indebtedness of the Company or any Restricted Subsidiary to declare a
     default on such other Indebtedness or cause the payment thereof to be
     accelerated or payable prior to its stated maturity;



                                       33





          (3) any Investment in such Subsidiary deemed to be made as a result of
     designating such Subsidiary an Unrestricted Subsidiary will not violate the
     provisions of Section 4.7 of the Indenture;

          (4) neither the Company nor any Restricted Subsidiary has a contract,
     agreement, arrangement, understanding or obligation of any kind, whether
     written or oral, with such Subsidiary other than (A) those that might be
     obtained at the time from Persons who are not Affiliates of the Company or
     (B) administrative, tax sharing and other ordinary course contracts,
     agreements, arrangements and understandings or obligations entered into in
     the ordinary course of business; and

          (5) neither the Company nor any Restricted Subsidiary has any
     obligation to subscribe for additional shares of Capital Stock or other
     Equity Interests in such Subsidiary, or to maintain or preserve such
     Subsidiary's financial condition or to cause such Subsidiary to achieve
     certain levels of operating results other than as permitted under Section
     4.7 of the Indenture.

     Notwithstanding the foregoing, the Company may not designate as an
Unrestricted Subsidiary any Subsidiary which, on the 1999 Indenture Date, was a
Significant Subsidiary, and may not sell, transfer or otherwise dispose of any
properties or assets of any such Significant Subsidiary to an Unrestricted
Subsidiary, other than in the ordinary course of business, in each case other
than Iron Mountain Global, Inc. and its Subsidiaries (including without
limitation Iron Mountain Europe Limited and its Subsidiaries).

     The Board of Directors may designate any Unrestricted Subsidiary as a
Restricted Subsidiary; provided that such designation will be deemed to be an
incurrence of Indebtedness by a Restricted Subsidiary of any outstanding
Indebtedness of such Unrestricted Subsidiary and such designation will only be
permitted if:

          (1) such Indebtedness is permitted under Section 4.8 of the Indenture
     and

          (2) no Default or Event of Default would occur as a result of such
     designation.

     (j) LIMITATION ON SALE AND LEASEBACK TRANSACTIONS.

     ss.4.15. LIMITATION ON SALE AND LEASEBACK TRANSACTIONS. The Company will
not, and will not permit any Restricted Subsidiary to, enter into any Sale and
Leaseback Transaction unless:

          (1) the consideration received in such Sale and Leaseback Transaction
     is at least equal to the fair market value of the property sold, as
     determined by a resolution of the Board of Directors and

          (2) the Company or such Restricted Subsidiary could incur the
     Attributable Indebtedness in respect of such Sale and Leaseback Transaction
     in compliance with Section 4.8 of the Indenture.

     (k) ASSET SALES.



                                       34




     ss.4.16. ASSET SALES. The Company shall not, and shall not permit any of
its Restricted Subsidiaries to:

          (1) sell, lease, convey or otherwise dispose of any assets (including
     by way of a Sale and Leaseback Transaction, but excluding a Qualifying Sale
     and Leaseback Transaction) other than sales of inventory in the ordinary
     course of business (provided that the sale, lease, conveyance or other
     disposition of all or substantially all of the assets of the Company will
     be governed by the provisions of Section 4.17 of the Indenture and/or the
     provisions of Section 5.1 of the Indenture and not by the provisions of
     this Section 4.16); or

          (2) issue or sell Equity Interests of any of its Restricted
     Subsidiaries

that in the case of either clause (1) or (2) above, whether in a single
transaction or a series of related transactions:

     (i) have a fair market value in excess of $2.0 million or

     (ii) result in Net Proceeds in excess of $2.0 million (each of the
foregoing, an "ASSET SALE"), unless (x) the Company (or the Restricted
Subsidiary, as the case may be) receives consideration at the time of such Asset
Sale at least equal to the fair market value (evidenced by an Officers'
Certificate delivered to the Trustee, and for Asset Sales having a fair market
value or resulting in Net Proceeds in excess of $10.0 million, evidenced by a
resolution of the Board of Directors set forth in an Officers' Certificate
delivered to the Trustee) of the assets sold or otherwise disposed of and (y) at
least 75% of the consideration therefor received by the Company or such
Restricted Subsidiary is in the form of cash or like-kind assets (in each case
as determined in good faith by the Company, evidenced by a resolution of the
Board of Directors and certified by an Officers' Certificate delivered to the
Trustee);

provided, however, that the amount of

     (A) any liabilities (as shown on the Company's or such Restricted
Subsidiary's most recent balance sheet or in the notes thereto) of the Company
or such Restricted Subsidiary (other than liabilities that are by their terms
subordinated to the Notes or any Subsidiary Guarantee) that are assumed by the
transferee of any such assets and

     (B) any notes or other obligations received by the Company or such
Restricted Subsidiary from such transferee that are immediately converted by the
Company or such Restricted Subsidiary into cash (to the extent of the cash
received) or Cash Equivalents,

shall be deemed to be cash for purposes of this provision; and provided,
further, that the 75% limitation referred to in the foregoing clause (ii) (y)
shall not apply to any Asset Sale in which the cash portion of the consideration
received therefrom is equal to or greater than what the after-tax proceeds would
have been had such Asset Sale complied with the aforementioned 75% limitation.



                                       35






     A transfer of assets or issuance of Equity Interests by the Company to a
Wholly Owned Restricted Subsidiary or by a Wholly Owned Restricted Subsidiary to
the Company or to another Wholly Owned Restricted Subsidiary will not be deemed
to be an Asset Sale.

     Within 360 days of any Asset Sale, the Company may, at its option, apply an
amount equal to the Net Proceeds from such Asset Sale either:

          (1) to permanently reduce Senior Debt or

          (2) to an investment in a Restricted Subsidiary or in another business
     or capital expenditure or other long-term/tangible assets, in each case, in
     the same line of business as the Company or any of its Restricted
     Subsidiaries was engaged in on the date of the First Supplemental Indenture
     or in businesses similar or reasonably related thereto.

     Pending the final application of any such Net Proceeds, the Company may
temporarily reduce Senior Bank Debt or otherwise invest such Net Proceeds in
any manner that is not prohibited by the Indenture. Any Net Proceeds from
such Asset Sale that are not applied or invested as provided in the first
sentence of this paragraph will be deemed to constitute "EXCESS PROCEEDS."
When the aggregate amount of Excess Proceeds exceeds $10.0 million, the
Company shall make an offer to all Holders of the Notes, all holders of the
9 1/8% Notes, the 8 1/4% Notes, the 8 1/8% Notes and the 8 3/4% Notes and the
holders of any future Indebtedness ranking PARI PASSU with the Notes, which
Indebtedness contains similar provisions requiring the Company to repurchase
such Indebtedness (an "ASSET SALE OFFER"), to purchase the maximum principal
amount of Notes and such other Indebtedness that may be purchased out of the
Excess Proceeds, at an offer price in cash in an amount equal to 100% of the
principal amount thereof plus accrued and unpaid interest, if any, to the
date of purchase, in accordance with the procedures set forth in the
Indenture; PROVIDED, HOWEVER, that prior to making any such Asset Sale Offer,
the Company may, to the extent required by the indentures for the 10 1/8%
Notes or the 11 1/8% Notes, use such Excess Proceeds to repurchase the
10 1/8% Notes and the 11 1/8% Notes. To the extent that the aggregate amount
of Notes and other PARI PASSU Indebtedness (including the 9 1/8% Notes, the
8 1/4% Notes, the 8 1/8% Notes and the 8 3/4% Notes) tendered pursuant to an
Asset Sale Offer is less than the Excess Proceeds, the Company may use any
remaining Excess Proceeds for general corporate purposes. If the aggregate
principal amount of Notes and such other Indebtedness surrendered by Holders
thereof exceeds the amount of Excess Proceeds, the Trustee shall select the
Notes and such other Indebtedness to be purchased on a pro rata basis. Upon
completion of such offer to purchase, the amount of Excess Proceeds shall be
reset at zero.

     The Company shall comply with the requirements of Rule 14e-1 under the
Exchange Act and any other securities laws and regulations thereunder to the
extent those laws and regulations are applicable in connection with each
repurchase of Notes pursuant to an Asset Sale Offer. To the extent that the
provisions of any securities laws or regulations conflict with the provisions of
this Section 4.16 of the Indenture, the Company shall comply with the applicable
securities laws and regulations and shall not be deemed to have breached its
obligations under the Asset Sale provisions of the Indenture by virtue of such
conflict.

     An Asset Sale Offer shall be made pursuant to the provisions of Section 3.9
hereof. No later than the date which is five Business Days after the date on
which the aggregate amount of Excess



                                       36




Proceeds exceeds $10.0 million, the Company shall notify the Trustee of such
Asset Sale Offer and provide the Trustee with an Officers' Certificate setting
forth the calculations used in determining the amount of Net Proceeds to be
applied to the purchase of Notes. The Company shall commence or cause to be
commenced the Asset Sale Offer on a date no later than 15 Business Days after
such notice (the "COMMENCEMENT DATE").

          (l) CHANGE OF CONTROL OFFER.

     ss. 4.17. CHANGE OF CONTROL OFFER.

     (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
offer described below (the "CHANGE OF CONTROL OFFER") at an offer price in cash
equal to 101% of the aggregate principal amount thereof plus accrued and unpaid
interest to but excluding the date of repurchase (the "CHANGE OF CONTROL
PAYMENT").

     Within 30 calendar days following any Change of Control, the Company shall
mail a notice to each Holder stating:

          (1) that the Change of Control Offer is being made pursuant to this
     Section 4.17 and that all Notes tendered shall be accepted for payment;

          (2) the purchase price and the purchase date, which shall be no
     earlier than 30 calendar days nor later than 60 calendar days from the date
     such notice is mailed (the "CHANGE OF CONTROL PAYMENT DATE");

          (3) that any Note not tendered shall continue to accrue interest;

          (4) that, unless the Company defaults in the payment of the Change of
     Control Payment, all Notes accepted for payment pursuant to the Change of
     Control Offer shall cease to accrue interest on and after the Change of
     Control Payment Date;

          (5) that Holders electing to have any Notes purchased pursuant to a
     Change of Control Offer shall be required to surrender the Notes, with the
     form entitled "Option of Holder to Elect Purchase" on the reverse of the
     Notes completed, to the paying agent at the address specified in such
     notice prior to the close of business on the fifth Business Day preceding
     the Change of Control Payment Date;

          (6) that Holders will be entitled to withdraw their election if the
     Paying Agent receives, not later than the close of business on the second
     Business Day preceding the Change of Control Payment Date, facsimile
     transmission or letter setting forth the name of the Holder, the principal
     amount of Notes delivered for purchase, and a statement that such Holder is
     withdrawing its election to have such Notes purchased; and

          (7) that Holders whose Notes are being purchased only in part will be
     issued new Notes equal in principal amount to the unpurchased portion of
     the Notes


                                       37


     surrendered, which unpurchased portion must be equal to $1,000 in principal
     amount or an integral multiple thereof.

     The Company shall comply with the requirements of Rule 14e-1 under the
Exchange Act and any other securities laws and regulations thereunder to the
extent such laws and regulations are applicable to the repurchase of the Notes
in connection with a Change of Control. To the extent that the provisions of any
securities laws or regulations conflict with this Section 4.17, the Company
shall comply with the applicable securities laws and regulations and shall not
be deemed to have breached its obligations under the Indenture or the First
Supplemental Indenture by virtue of such conflict.

     (b) On the Change of Control Payment Date, the Company shall, to the extent
lawful:

          (1) accept for payment Notes or portions thereof tendered pursuant to
     the Change of Control Offer;

          (2) deposit with the Paying Agent an amount equal to the Change of
     Control Payment in respect of all Notes or portions thereof so tendered;
     and

          (3) deliver or cause to be delivered to the Trustee the Notes so
     accepted together with an Officers' Certificate stating the Notes or
     portions thereof tendered to the Company.

     The Paying Agent shall promptly mail to each Holder of Notes so accepted
the Change of Control Payment for such Notes, and the Trustee shall promptly
authenticate and mail to each Holder a new Note equal in principal amount to any
unpurchased portion of the Notes surrendered, if any; provided that each such
new Note shall be in a principal amount of $1,000 or an integral multiple
thereof. Prior to complying with the provisions of this Section 4.17, but in any
event within 90 calendar days following a Change of Control, the Company shall
either repay all outstanding Senior Debt or obtain the requisite consents, if
any, under all agreements governing outstanding Senior Debt to permit the
repurchase of Notes required by this Section 4.17. The Company shall publicly
announce in The Wall Street Journal, or if no longer published, a national
newspaper of general circulation, the results of the Change of Control Offer on
or as soon as practicable after the Change of Control Payment Date.

     The Company shall not be required to make a Change of Control Offer upon a
Change of Control if a third party makes the Change of Control Offer in the
manner, at the times and otherwise in compliance with the requirements set forth
in this Section 4.17 applicable to a Change of Control Offer made by the Company
and purchases all Notes properly tendered and not withdrawn under the Change of
Control Offer.

     (m) CORPORATE EXISTENCE.

     With respect to the Notes issued under this First Supplemental Indenture,
Section 4.5 of the Indenture is replaced in its entirety as follows:

     ss. 4.5. CORPORATE EXISTENCE.



                                       38




     Subject to Section 4.13 and Article V of the Indenture, as the case may be,
the Company and each of the Restricted Subsidiaries shall do or cause to be done
all things necessary to preserve and keep in full force and effect (i) its
corporate existence, and the corporate, partnership or other existence of each
of their Subsidiaries, in accordance with the respective organizational
documents (as the same may be amended from time to time) of the Company, any
such Restricted Subsidiary or any such Subsidiary, as the case may be, and (ii)
the rights (charter and statutory), licenses and franchises of the Company, the
Restricted Subsidiaries and their respective Subsidiaries; PROVIDED, HOWEVER,
that the Company and the Restricted Subsidiaries shall not be required to
preserve any such right, license or franchise, or the corporate, partnership or
other existence of any of their respective Subsidiaries, if an officer of the
Company shall determine that the preservation thereof is no longer desirable in
the conduct of the business of the Company, the Restricted Subsidiaries and
their Subsidiaries, taken as a whole, and that the loss thereof is not adverse
in any material respect to the Holders of the Notes.

     Section 2.7. MERGERS, CONSOLIDATIONS, OR SALE OF ASSETS.

     With respect to the Notes issued under this First Supplemental Indenture,
Section 5.1 of the Indenture is replaced in its entirety as follows:

     ss.5.1. MERGERS, CONSOLIDATIONS, 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 Person unless:

          (1) the Company is the surviving corporation 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 States, any state thereof or the District of
     Columbia;

          (2) the Person formed by or surviving any such consolidation or merger
     (if other than the Company) or the Person to which such sale, assignment,
     transfer, lease, conveyance or other disposition shall have been made
     assumes all the obligations of the Company under the Notes, the First
     Supplemental Indenture and the Indenture (pursuant to a supplemental
     indenture in a form reasonably satisfactory to the Trustee);

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

          (4) the Company or any Person formed by or surviving any such
     consolidation or merger, or to which such sale, assignment, transfer,
     lease, conveyance or other disposition shall have been made, will, at the
     time of such transaction and after giving pro forma effect thereto, be
     permitted to incur at least $1.00 of additional Indebtedness pursuant to
     the test set forth in the first paragraph of Section 4.8 of the Indenture.



                                       39




          Section 2.8. EVENTS OF DEFAULT.

     With respect to the Notes issued under this First Supplemental Indenture,
Section 6.1 of the Indenture is hereby replaced in its entirety as follows:

     ss.6.1. EVENTS OF DEFAULT.

     Each of the following constitutes an "Event of Default:"

          (1) default for 30 days in the payment when due of interest on the
     Notes (whether or not prohibited by the subordination provisions of Article
     XIII of the Indenture);

          (2) default in payment when due of the principal of or premium, if
     any, on the Notes (whether or not prohibited by the subordination
     provisions in Article XIII of the Indenture);

          (3) failure by the Company to comply with Section 4.17 of the
     Indenture;

          (4) failure by the Company or any Guarantor for 60 days after written
     notice from the Trustee or Holders of not less than 25% of the aggregate
     principal amount of the Notes (including the Additional Notes, if any) then
     outstanding to comply with any of its other agreements in the Indenture,
     the First Supplemental Indenture, the Notes or the Subsidiary Guarantees
     (in order to be effective, such notice must be in writing, specify the
     Default, demand that it be remedied and state that the notice is a "Notice
     of Default");

          (5) 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 of its Restricted
     Subsidiaries (or the payment of which is guaranteed by the Company or any
     of its Restricted Subsidiaries) whether such Indebtedness or guarantee
     exists on the date of the First Supplemental Indenture or is created
     thereafter, if:

               (i) such default results in the acceleration of such Indebtedness
          prior to its express maturity or shall constitute a default in the
          payment of such Indebtedness at final maturity of such Indebtedness
          and

               (ii) the principal amount of any such Indebtedness that has been
          accelerated or not paid at maturity, when added to the aggregate
          principal amount of all other such Indebtedness that has been
          accelerated or not paid at maturity, exceeds $10.0 million;

          (6) a final judgment or final judgments for the payment of money are
     entered by a court or courts of competent jurisdiction against the Company
     or any of its Restricted Subsidiaries and such judgments remain unpaid,
     undischarged or unstayed for a period of 60 days, provided that the
     aggregate of all such unpaid, undischaraged or unstayed judgments exceeds
     $10.0 million;



                                       40




          (7) the Company or any of its Restricted Subsidiaries that is a
     Significant Subsidiary:

               (i) commences a voluntary case,

               (ii) consents to the entry of an order for relief against it in
          an involuntary case,

               (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) admits in writing that it generally is unable to pay its
          debts as the same become due;

          in each case, pursuant to or within the meaning of any Bankruptcy
          Law; or

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

               (i) is for relief against the Company or any of its Restricted
          Subsidiaries that is a Significant Subsidiary in an involuntary case,

               (ii) appoints a Custodian of the Company or any of its Restricted
          Subsidiaries that is a Significant Subsidiary or for all or
          substantially all of its property, or

               (iii) orders the liquidation of the Company or any of its
          Restricted Subsidiaries that is a Significant Subsidiary,

          and such order or decree remains unstayed and in effect for 60 days;
          or

          (9) except as permitted by the Indenture, the First Supplemental
     Indenture or the Subsidiary Guarantees, any Subsidiary Guarantee issued by
     a Restricted Subsidiary shall be held in any judicial proceeding to be
     unenforceable or invalid or shall cease for any reason to be in full force
     and effect, or any Restricted Subsidiary or any Person acting on behalf of
     any Restricted Subsidiary shall deny or disaffirm in writing its
     obligations under its Subsidiary Guarantee.

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

Section 2.9. ACCELERATION.

     With respect to the Notes issued under this First Supplemental Indenture,
Section 6.2 of the Indenture is hereby replaced in its entirety as follows:

     ss.6.2. ACCELERATION OF MATURITY.



                                       41



     If any Event of Default (other than an Event of Default specified in
clauses (7)(i) through (7)(v) and (8) of Section 6.1 of the Indenture relating
to the Company or any of its Restricted Subsidiaries that is a Significant
Subsidiary) 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 the unpaid principal of and
any interest on all the Notes to be due and payable immediately; provided,
however, that if any Obligation with respect to Senior Bank Debt is outstanding
pursuant to the Credit Agreement upon a declaration of acceleration of the
Notes, the principal, premium, if any, and interest on the Notes will not be
payable until the earlier of:

          (1) the day which is five Business Days after written notice of
     acceleration is received by the Company and the Credit Agent or

          (2) the date of acceleration of the Indebtedness under the Credit
     Agreement. If an Event of Default specified in clauses (7)(i) through
     (7)(v) and (8) of Section 6.1 of the Indenture with respect to the Company
     or any Restricted Subsidiary that is a Significant Subsidiary occurs, the
     principal of, and premium, if any, and any accrued and unpaid interest on
     all outstanding Notes will become immediately due and payable without
     further action or notice.

     In the event of a declaration of acceleration of the Notes because an Event
of Default has occurred and is continuing as a result of the acceleration of any
Indebtedness described in clause (5) of Section 6.1 of the Indenture, the
declaration of acceleration of the Notes shall be automatically annulled if the
holders of any Indebtedness described in such clause have rescinded the
declaration of acceleration in respect of such Indebtedness within 30 days from
the date of such declaration and if:

          (1) the annulment of the acceleration of the Notes would not conflict
     with any judgment or decree of a competent jurisdiction and

          (2) all existing Events of Default, except non-payment of principal or
     interest on the Notes that became due solely because of the acceleration of
     the Notes, have been cured or waived.

     In the case of any Event of Default 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 Make Whole Price or premium, as
applicable, that the Company would have had to pay if the Company then had
elected to redeem the Notes pursuant to the optional redemption provisions of
the Indenture, the applicable Make Whole Price, or an equivalent premium, as the
case may be, shall become and be immediately due and payable to the extent
permitted by law upon the acceleration of the Notes.

Section 2.10. AMENDMENTS AND WAIVERS.

     With respect to the Notes issued under this First Supplemental Indenture,
the following Sections replace in their entirety Sections 9.1, 9.2, 9.3 and 9.5
of the Indenture:



                                       42




     ss.9.1. WITHOUT CONSENT OF HOLDERS.

     Notwithstanding Section 9.2 of the Indenture, without the consent of any
Holder of Notes, the Company, the Guarantors and the Trustee may amend or
supplement the Indenture or the Notes:

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

     (b) to provide for uncertificated Notes in addition to or in place of
certificated Notes,

     (c) to provide for the assumption of the Company's or any Guarantor's
obligations to Holders of the Notes in the case of a merger or consolidation,

     (d) to make any change that would provide any additional rights or benefits
to the Holders of the Notes (including providing for additional Subsidiary
Guarantees pursuant to Section 4.13 of the Indenture) or that does not
materially adversely affect the legal rights under the Indenture of any such
Holder, or

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

     Upon the request of the Company accompanied by a resolution of its Board of
Directors authorizing the execution of any such amended or supplemental
Indenture, and upon receipt by the Trustee of the documents described in Section
7.2 of the Indenture, the Trustee shall join with the Company and the Guarantors
in the execution of any amended or supplemental Indenture authorized or
permitted by the terms of this Indenture and to make any further appropriate
agreements and stipulations that may be therein contained, but the Trustee shall
not be obligated to enter into such amended or supplemental Indenture that
affects its own rights, duties or immunities under this Indenture or otherwise.

ss.9.2. WITH CONSENT OF HOLDERS.

     Except as provided Section 9.1 and Section 9.3 of the Indenture, 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 Notes then outstanding
(including consents obtained in connection with a tender offer or exchange offer
for Notes), and, subject to Sections 6.8 and 6.12 of the Indenture) any existing
Default or Event of Default (other than a Default or Event of Default in the
payment of the principal of, premium, if any, or interest on the Notes, except a
payment default resulting from an acceleration that has been rescinded) or
compliance with any provision of the Indenture or the Notes may be waived with
the consent of the Holders of a majority in principal amount of the then
outstanding Notes (including consents obtained in connection with a tender offer
or exchange offer for Notes).

     It shall not be necessary for the consent of the Holders of Notes under
this Section 9.2 to approve the particular form of any proposed amendment or
waiver, but it shall be sufficient if such consent approves the substance
thereof.

     Upon the request of the Company accompanied by a resolution of its Board of
Directors authorizing the execution of any such amended or supplemental
Indenture, and upon the filing with the Trustee of evidence reasonably
satisfactory to the Trustee of the consent of the Holders of Notes as



                                       43





aforesaid, and upon receipt by the Trustee of the documents described in Section
7.2 hereof, the Trustee shall join with the Company and the Guarantors in the
execution of such amended or supplemental Indenture unless such amended or
supplemental Indenture affects the Trustee's own rights, duties or immunities
under this Indenture or otherwise, in which case the Trustee may in its
discretion, but shall not be obligated to, enter into such amended or
supplemental Indenture.

     ss.9.3. LIMITATIONS.

     Without the consent of each Holder affected, an amendment or waiver may not
(with respect to any Notes held by a non-consenting Holder of Notes):

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

          (2) reduce the principal of or change the fixed maturity of any Note
     or alter any of the provisions with respect to the redemption of the Notes
     in a manner adverse to the Holders of the Notes;

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

          (4) waive a Default or Event of Default in the payment of principal of
     or premium, if any, or interest on the Notes (except a rescission of
     acceleration of the Notes by the Holders of at least a majority in
     aggregate principal amount of the then outstanding Notes and a waiver of
     the payment default that resulted from such acceleration);

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

          (6) make any change in the provisions of the Indenture relating to
     waivers of past Defaults or the rights of Holders of Notes to receive
     payments of principal of or premium, if any, or interest on the Notes;

          (7) waive a redemption payment with respect to any Note (other than a
     payment required by Section 4.16 and Section 4.17 of the Indenture);

          (8) except pursuant to the Indenture, release any Guarantor from its
     obligations under its Subsidiary Guarantee, or change any Subsidiary
     Guarantee in any manner that would materially adversely affect the Holders;
     or

          (9) make any change in the foregoing amendment and waiver provisions.

     It shall not be necessary for the consent of the Holders of Notes under
this Section 9.3 to approve the particular form of any proposed amendment or
waiver, but it shall be sufficient if such consent approves the substance
thereof.



                                       44




     ss.9.5. REVOCATION AND EFFECT OF CONSENTS.

     Until an amendment 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 the amendment or waiver becomes effective.

     Any amendment or waiver once effective shall bind every Holder unless it is
of the type described in any of clauses (1) through (8) of Section 9.3. In that
case, the amendment or waiver shall bind each Holder who has consented to it and
every subsequent Holder of a Note or portion of a Note that evidences the same
debt as the consenting Holder's Note.

Section 2.11. SUBSIDIARY GUARANTEES.

     With respect to the Notes issued under this Supplemental Indenture, Article
XII of the Indenture shall apply, and the Notes shall constitute a Series to be
guaranteed by the Guarantors pursuant to Article XII of the Indenture.

Section 2.12. LEGAL DEFEASANCE AND COVENANT DEFEASANCE.

     With respect to the Notes issued under this Supplemental Indenture, Article
VIII of the Indenture shall apply, and the Company shall have the option to
effect Legal Defeasance or Covenant Defeasance pursuant to Article VIII of the
Indenture. In connection with any Covenant Defeasance, the Company shall be
released from its obligations under the covenants specified in Sections 2.6 and
2.7 of this First Supplemental Indenture.

Section 2.13. SUBORDINATION.

     (a) With respect to the Notes issued under this Supplemental Indenture,
Article XIII of the Indenture shall apply, and the Notes shall be subject to
subordination pursuant to Article XIII of the Indenture. In addition, with
respect to the Notes issued under this First Supplemental Indenture, the
following Sections shall be added to Article XIII of the Indenture.

     (b) Guarantors May Consolidate, etc., on Certain Terms.

     ss.13.27. GUARANTORS MAY CONSOLIDATE, ETC., ON CERTAIN TERMS.

     No Guarantor shall consolidate with or merge with or into (whether or
not such Guarantor is the surviving Person), another Person whether or not it
is affiliated with such Guarantor unless (i) subject to the provisions of
Section 11.28 hereof, the Person formed by or surviving any such
consolidation or merger (if other than a Guarantor) assumes all the
obligations of such Guarantor pursuant to a supplemental indenture in form
reasonably satisfactory to the Trustee, under its Subsidiary Guarantee, the
Notes and this Indenture, (ii) immediately after giving effect to such
transaction, no Default or Event of Default exists, and (iii) such Guarantor,
or any Person formed by or surviving any such consolidation or merger, will
be permitted to incur, immediately after giving effect to such transaction,
at least $1.00 of additional Indebtedness pursuant to the first paragraph of
Section 4.8 hereof. In case of any such consolidation, merger, sale or
conveyance and upon the assumption by the

                                       45




successor Person, by supplemental indenture, executed and delivered to the
Trustee and satisfactory in form to the Trustee, of the Subsidiary Guarantee
in this Indenture and the due and punctual performance and observance of all
of the covenants and conditions of this Indenture to be performed by the
Guarantor, such successor Person shall succeed to and be substituted for the
Guarantor with the same effect as if it had been named herein as a Guarantor.

     (c) Releases Following Sale of Assets or Designation as Unrestricted
Subsidiary.

     ss.13.28. RELEASES FOLLOWING SALE OF ASSETS OR DESIGNATION AS UNRESTRICTED
SUBSIDIARY.

     In the event of (a) a sale or other disposition of all or substantially
all of the assets of any Guarantor, by way of merger, consolidation or
otherwise, or (b) a sale or other disposition of all of the capital stock of
any Guarantor, or (c) the designation of a Restricted Subsidiary as an
Unrestricted Subsidiary in accordance with the terms of Section 4.14 hereof,
then such Guarantor (in the event of a sale or other disposition, by way of
such a merger, consolidation or otherwise, of all of the capital stock of
such Guarantor, or in the event of the designation of such Guarantor as an
Unrestricted Subsidiary) or the Person acquiring the property (in the event
of a sale or other disposition of all or substantially all of the assets of
such Guarantor) shall be released and relieved of its obligations under its
Subsidiary Guarantee; provided that the Net Proceeds of such sale or other
disposition are applied in accordance with Section 4.16 hereof.

                                   ARTICLE 3.

                                  MISCELLANEOUS

Section 3.1. EFFECT OF HEADINGS.

     The Article and Section headings herein are for convenience only and shall
not affect the construction hereof.

Section 3.2. SUCCESSORS AND ASSIGNS.

     All covenants and agreements in this First Supplemental Indenture by the
Company shall bind its successors and assigns, whether so expressed or not.

Section 3.3. SEPARABILITY CLAUSE.

     In case any provision in this First Supplemental 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.



                                       46





Section 3.4. GOVERNING LAW.

     This First Supplemental Indenture and the Notes created hereby shall be
governed by and construed in accordance with the laws of the State of New York
without giving effect to any conflicts of law provisions (other than Section
5-1401 of the New York General Obligations Law) that might cause this First
Supplemental Indenture and the Notes to be governed by or construed or enforced
in accordance with the laws of any other jurisdiction.

Section 3.5. FIRST SUPPLEMENT TO SUPERSEDE INDENTURE.

     The Indenture, as supplemented by this First Supplemental Indenture,
remains in full force and effect as of the date hereof. Notwithstanding the
foregoing, to the extent that any provision of the Indenture shall conflict
with any provision of this First Supplemental Indenture, the terms of this
First Supplemental Indenture shall be deemed controlling and the conflicting
provision of the Indenture shall be null and void to the extent of such
conflict.

           [THE REST OF THIS PAGE HAS BEEN INTENTIONALLY LEFT BLANK.]



                                       47




     IN WITNESS WHEREOF, the parties have caused this First Supplemental
Indenture to be duly executed, and attested, all as of the date and year first
written above.



                           IRON MOUNTAIN INCORPORATED


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


                           ARCUS DATA SECURITY, INC.
                           COMAC, INC.
                           DSI TECHNOLOGY ESCROW SERVICES, INC.
                           IM BILLERICA, INC.
                           IRON MOUNTAIN GLOBAL, INC.
                           IRON MOUNTAIN RECORDS MANAGEMENT, INC.
                           IRON MOUNTAIN RECORDS MANAGEMENT OF MICHIGAN, INC.


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


                           IRON MOUNTAIN/NATIONAL UNDERGROUND STORAGE, LLC
                           IRON MOUNTAIN CONSULTING SERVICES, LLC
                           IRON MOUNTAIN CONFIDENTIAL DESTRUCTION LLC

                           By:  Iron Mountain Records Management, Inc.,
                                 its sole Member


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


                           [Indenture Signature Page]







                           IRON MOUNTAIN GLOBAL LLC

                           By:  Iron Mountain Global, Inc., its sole Member


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


                           ARCUS DATA SECURITY LLC

                           By:  Arcus Data Security, Inc., its sole Member

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



                  [First Supplemental Indenture Signature Page]





                           THE BANK OF NEW YORK, as Trustee



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


                  [First Supplemental Indenture Signature Page]





                                                                       EXHIBIT A




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


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




                                 [Face of Note]
                    8 5/8% Senior Subordinated Notes due 2013

No.  ___________________                                       $_______________


                           IRON MOUNTAIN INCORPORATED

promises to pay to _______ or registered assigns, the principal sum of ________
Dollars on April 1, 2013.

     Interest Payment Dates: April 1 and October 1

     Record Dates: March 15 and September 15

     Dated: April [ ], 2001


     CUSIP No. ________________


                               IRON MOUNTAIN INCORPORATED



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


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


                                     (SEAL)


This is one of the Notes
referred to in the within-
mentioned Indenture:

THE BANK OF NEW YORK,
as Trustee


By:
   -----------------------------------------
            Authorized Signature






                                 [Back of Note]
                    8 5/8% Senior Subordinated Notes due 2013

     [INSERT IN GLOBAL NOTES] [This Security is a Global Security within the
meaning of the Indenture hereinafter referred to and is registered in the name
of the Depository or a nominee of the Depository. This Security is exchangeable
for Securities registered in the name of a person other than the Depository or
its nominee only in the limited circumstances described in the Indenture, and
may not be transferred except as a whole by the Depository to a nominee of the
Depository, by a nominee of the Depository to the Depository or another nominee
of the Depository or by the Depository or any such nominee to a successor
Depository or a nominee of such a successor Depository.]

     Unless and until it is exchanged in whole or in part for Notes in
definitive form, this Note may not be transferred except as a whole by the
Depository to a nominee of the Depository or by a nominee of the Depository to
the Depository or another nominee of the Depository or by the Depository or any
such nominee to a successor Depository or a nominee of such successor
Depository. Unless this certificate is presented by an authorized representative
of The Depository Trust Company (55 Water Street, New York, New York) ("DTC"),
to the issuer 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 may be requested by an authorized representative of DTC (and any payment
is made to Cede & Co. or such other entity as may be 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.

     Capitalized terms used herein shall have the meanings assigned to them in
the Indenture referred to below unless otherwise indicated.

     1. INTEREST. Iron Mountain Incorporated, a Pennsylvania corporation (the
"COMPANY") promises to pay interest on the principal amount of this Note at 8
5/8% per annum from April [ ], 2001 until April 1, 2013. The Company shall
pay interest, semi-annually in arrears on April 1 and October 1 of each year,
or if any such day is not a Business Day, on the next succeeding Business Day
(each an "INTEREST PAYMENT DATE"). 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 the date of issuance; PROVIDED that if there is no existing
Default in the payment of interest, and if this Note is authenticated between
a record date referred to on the face hereof and the next succeeding Interest
Payment Date, interest shall accrue from such next succeeding Interest
Payment Date; PROVIDED, FURTHER, that the first Interest Payment Date shall
be October 1, 2001. The Company shall pay interest (including post-petition
interest to the extent allowed in any proceeding under any Bankruptcy Law) on
overdue principal from time to time on demand at a rate equal to the per
annum rate on the Notes then in effect; it shall pay interest (including
post-petition interest to the extent allowed in any proceeding under any
Bankruptcy Law) on overdue installments of interest (without regard to any
applicable grace periods) from time to time on demand at the same rate to the
extent lawful. Interest will be computed on the basis of a 360-day year of
twelve 30-day months.

     2. METHOD OF PAYMENT. The Company will pay principal and interest in money
of the United States that at the time of payment is legal tender for payment of
public and private debts. The Company, however, may pay principal, premium, if
any, and interest by check payable in such money. It may mail an interest check
to a Holder's registered address.







     3. PAYING AGENT, REGISTRAR AND SERVICE AGENT. Initially, The Bank of New
York, the Trustee under the Indenture, will act as Paying Agent, Registrar and
Service Agent. The Notes may be presented for registration of transfer and
exchange at the offices of the Registrar. The Company may change any Paying
Agent, Service Agent or Registrar without notice to any Holder. The Company or
any of its Subsidiaries may act in any such capacity.

     4. INDENTURE. The Company issued the Notes under an Indenture dated as of
April 3, 2001 (the "BASE Indenture") as supplemented by a First Supplemental
Indenture dated as of April 3, 2001 (the "SUPPLEMENTAL INDENTURE" and, together
with the Base Indenture, the "INDENTURE") among the Company, the Guarantors and
the Trustee. The terms of the Notes include those stated in the Indenture and
those made part of the Indenture by reference to the Trust Indenture Act of
1939, as amended (15 U.S. Code ss.ss. 77aaa-77bbbb). The Notes are subject to
all such terms, and Holders are referred to the Indenture and such Act for a
statement of such terms. The terms of the Indenture shall govern any
inconsistencies between the Indenture and the Notes. The Notes issued under the
Indenture are subordinated unsecured obligations of the Company limited to
$500,000,000 in aggregate principal amount.

     5. OPTIONAL REDEMPTION.

     Prior to April 1, 2006, the Notes will be subject to redemption at any time
at the option of the Company, in whole or in part, upon not less than 30 nor
more than 60 days' notice, at the Make-Whole Price, plus accrued and unpaid
interest thereon to the applicable redemption date. At any time on or after
April 1, 2006, the Company may redeem any portion of the Notes, in whole or in
part, on at least 30 days, but no more than 60 days' notice at the following
prices (expressed as a percentage of the principal amount), together with
accrued and unpaid interest to, but excluding, the redemption date:



                  REDEMPTION PERIOD                            REDEMPTION PRICE
                                                               
April 1, 2006 to March 31, 2007...........................          104.313%
April 1, 2007 to March 31, 2008...........................          102.875%
April 1, 2008 to March 31, 2009...........................          101.438%
April 1, 2009 and thereafter..............................          100.000%



     Notwithstanding the foregoing, at any time prior to April 1, 2004, the
Company may redeem up to 35% of the initial principal amount of the Notes
originally issued with the net proceeds of one or more Qualified Equity
Offerings at a redemption price equal to 108.625% of the principal amount of
such Notes, plus accrued and unpaid interest, if any, to the date of
redemption; provided, that at least 65% of the principal amount of Notes
originally issued remains outstanding immediately after the occurrence of any
such redemption and that such redemption occurs within 60 days following the
closing of any such Qualified Equity Offering.

     6. 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
such Holder's address of record. The Notes in denominations larger than $1,000
may be redeemed in part but only in integral multiples of $1,000, unless all the
Notes held by a Holder are to be redeemed. 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.

     7. MANDATORY REDEMPTION. Except as set forth in paragraph 8 below, the
Company shall not be required to make mandatory redemption payments with respect
to the Notes. There are no sinking fund payments with respect to the Notes.

     8. REPURCHASE AT OPTION OF HOLDER. This Note is subject to purchase at the
option of the Holder upon the circumstances set forth in Sections 3.9, 4.16 and
4.17 of the Indenture.

     9. 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.

     10. DENOMINATIONS, TRANSFER, EXCHANGE. The Notes are in registered form
without coupons in minimum denominations of $1,000 and integral multiples of
$1,000 in excess thereof. The transfer of Notes may be registered and Notes may
be exchanged as provided in the Indenture.

     11. PERSONS DEEMED OWNERS. Prior to due presentment to the Trustee for
registration of the transfer of this Note, the Trustee, any Agent, the Company
and the Guarantors may deem and treat the Person in whose name this Note is
registered as its absolute owner for the purpose of receiving payment of
principal of, premium, if any, and interest on this Note and for all other
purposes whatsoever, whether or not this Note is overdue, and none of the
Trustee, any Agent, the Company or any Guarantor shall be affected by notice to
the contrary. The registered Holder of a Note may be treated as its owner for
all purposes.

     12. AMENDMENT, SUPPLEMENT AND WAIVER. Subject to certain exceptions, the
Indenture with respect to the Notes or the Notes may be amended or supplemented
with the written consent of the Holders of a majority in principal amount of the
then outstanding Notes, and any existing default or compliance with any
provision of the Indenture with respect to the Notes or the Notes may be waived
with the consent of the Holders of a majority in principal amount of the Notes
(including, in each case, Additional Notes, if any). Without the consent of any
Holder of the Notes, the Indenture with respect to the Notes or the Notes may be
amended or supplemented to, in addition to other events more fully described in
the Indenture, cure any ambiguity, defect or inconsistency, provide for
uncertificated Notes in addition to or in place of certificated Notes, provide
for the assumption of the Company's or a Guarantor's obligations to Holders of
the Notes in the case of a merger or consolidation, make any change that would
provide any additional rights or benefits to the Holders of the Notes or that
does not materially adversely affect the legal rights under the Indenture of any
such Holder, or comply with requirements of the SEC in order to effect or
maintain the qualification of the Indenture under the TIA.







     13. DEFAULTS AND REMEDIES. An Event of Default with respect to the Notes
includes: the default for 30 days in the payment when due of interest on the
Notes (whether or not prohibited by the subordination provisions of the
Indenture); the default in payment when due of the principal of or premium, if
any, on the Notes (whether or not prohibited by the subordination provisions of
the Indenture); the failure by the Company to comply with Section 4.17 of the
Indenture; the failure by the Company or any Guarantor for 60 days after written
notice from the Trustee or Holders of not less than 25% of the aggregate
principal amount of the Notes (including Additional Notes, if any) outstanding
to comply with any of its other agreements in the Indenture, Notes or the
Subsidiary Guarantees; the 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 of its Restricted
Subsidiaries (or the payment of which is guaranteed by the Company or any of its
Restricted Subsidiaries) whether such Indebtedness or guarantee exists on the
date of the Indenture or is created thereafter, if: (i) such default results in
the acceleration of such Indebtedness prior to its express maturity or shall
constitute a default in the payment of such Indebtedness at final maturity of
such Indebtedness and (ii) the principal amount of any such Indebtedness that
has been accelerated or not paid at maturity, when added to the aggregate
principal amount of all other such Indebtedness that has been accelerated or not
paid at maturity, exceeds $10.0 million; the failure by the Company or any of
its Restricted Subsidiaries to pay final judgments aggregating in excess of
$10.0 million, which judgments remain unpaid, undischarged or unstayed for a
period of 60 days; certain events of bankruptcy or insolvency with respect to
the Company or any of its Restricted Subsidiaries that is a Significant
Subsidiary; or except as permitted by the Indenture or the Subsidiary
Guarantees, any Subsidiary Guarantee issued by a Restricted Subsidiary shall be
held in any judicial proceeding to be unenforceable or invalid or shall cease
for any reason to be in full force and effect, or any Restricted Subsidiary or
any Person acting on behalf of any Restricted Subsidiary shall deny or disaffirm
in writing its obligations under its Subsidiary Guarantee.

     If any Event of Default occurs and is continuing, the Trustee or the
Holders of at least 25% in principal amount of the then outstanding Notes
(including Additional Notes, if any) may declare all the Notes to be due and
payable immediately; provided, however, that if any Obligation with respect to
Senior Bank Debt is outstanding pursuant to the Credit Agreement upon a
declaration of acceleration of the Notes, the principal, premium, if any, and
interest on the Notes will not be payable until the earlier of: (1) the day
which is five business days after written notice of acceleration is received by
the Company and the Credit Agent or (2) the date of acceleration of the
Indebtedness under the Credit Agreement. Notwithstanding the foregoing, in the
case of an Event of Default arising from certain events of bankruptcy or
insolvency with respect to the Company or any Restricted Subsidiary that is a
Significant Subsidiary, the principal of, and premium, if any, and any accrued
and unpaid interest on all outstanding Notes will become due and payable without
further action or notice. In the event of a declaration of acceleration of the
Notes because an Event of Default has occurred and is continuing as a result of
the acceleration of any Indebtedness described in Section 6.1(5) of the
Indenture, the declaration of acceleration of the Notes shall be automatically
annulled if the holders of any Indebtedness described in such section have
rescinded the declaration of acceleration in respect of such Indebtedness within
30 days from the date of such declaration and if: (1) the annulment of the
acceleration of the Notes would not conflict with any judgment or decree of a
competent jurisdiction and (2) all existing Events of Default, except
non-payment of principal or interest on the Notes that became due solely because
of the acceleration of the Notes, have been cured or waived.

     Subject to certain limitations, Holders of a majority in principal
amount of the then outstanding Notes may direct the Trustee in its exercise
of any trust or power. The Trustee may withhold from Holders of the Notes
notice of any continuing Default or Event of Default (except a Default or
Event of Default relating to the payment of principal or interest) if it
determines




that withholding notice is in their interest. The Company is required to deliver
to the Trustee annually a statement regarding compliance with the Indenture, and
the Company is required, upon becoming aware of any Default or Event of Default,
to deliver to the Trustee a statement specifying such Default or Event of
Default and what action the Company is taking or proposes to take thereto.

     14. SUBSIDIARY GUARANTEES. Payment of principal of, premium, if any, and
interest (including interest on overdue principal, premium, if any, and
interest, if lawful) on the Notes is guaranteed on an unsecured, senior
subordinated basis by the Guarantors pursuant to Article XII of the Indenture.

     15. TRUSTEE DEALINGS WITH COMPANY. The Trustee, in its individual or any
other capacity, may make loans to, accept deposits from, and perform services
for the Company or its Affiliates, and may otherwise deal with the Company or
its Affiliates, as if it were not the Trustee.

     16. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator or stockholder, as such, of the Company or any
Guarantor shall have any liability for any obligations of the Company or any
Guarantor under the Notes, the Subsidiary Guarantees 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 and the related Subsidiary Guarantees
waives and releases all such liability. The waiver and release are part of the
consideration for the issuance of the Notes.

     17. AUTHENTICATION. This Note shall not be valid until authenticated by the
manual signature of the Trustee or an authenticating agent.

     18. 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
U/G/M/A (= Uniform Gifts to Minors Act).

     19. CUSIP NUMBERS. Pursuant to a recommendation promulgated by the
Committee on Uniform Security Identification Procedures, the Company has caused
CUSIP numbers to be printed on the Notes and the Trustee may use CUSIP numbers
in notices of redemption as a convenience to Holders. No representation is made
as to the accuracy of such numbers either as printed on the Notes or as
contained in any notice of redemption and reliance may be placed only on the
other identification numbers placed thereon.

     The Company shall furnish to any Holder upon written request and without
charge a copy of the Indenture. Requests may be made to:

                           Iron Mountain Incorporated
                           745 Atlantic Avenue
                           Boston, Massachusetts 02111
                           Attention:  Chief Financial Officer






                                 ASSIGNMENT FORM


     To assign this Note, fill in the form below: (I) or (we) assign and
transfer this Note to

- -------------------------------------------------------------------------------
                  (Insert assignee's soc. sec. or tax I.D. no.)

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

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

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

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

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

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


Date:  __________

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

Signature Guarantee:






                       OPTION OF HOLDER TO ELECT PURCHASE


     If you want to elect to have this Note purchased by the Company pursuant to
Section 4.16 or 4.17 of the Indenture, check the box below:

                        /  /  Section 4.16

                        /  /  Section 4.17

     If you want to elect to have only part of the Note purchased by the Company
pursuant to Section 4.16 or 4.17 of the Indenture, state the amount you elect to
have purchased: $________


Date:  __________            Your Signature:
                                              ---------------------------------
                             (Sign exactly as your name appears on the Note)

                             Tax Identification No.:
                                                     --------------------------

Signature Guarantee:








                         SCHEDULE OF EXCHANGES OF NOTES


     The following exchanges of a part of this Global Note for Definitive Notes
have been made:



                                                                           Principal Amount of       Signature of
                           Amount of decrease    Amount of increase in      this Global Note       authorized office
                           in Principal Amount    Principal Amount of        following such          of Trustee or
    Date of Exchange       of this Global Note      this Global Note     decrease (or increase)      Service Agent
- ---------------------------------------------------------------------------------------------------------------------
                                                                                         







                                    EXHIBIT B

       FORM OF SUPPLEMENTAL INDENTURE TO BE DELIVERED BY FUTURE GUARANTORS

     SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as of
________________, _____, between __________________ (the "GUARANTOR"), a
subsidiary of Iron Mountain Incorporated (or its successor), a Pennsylvania
corporation (the "COMPANY"), and The Bank of New York, a New York banking
corporation, as trustee under the Indenture referred to below (the "TRUSTEE").

                               W I T N E S S E T H

     WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture, dated as of April 3, 2001, as supplemented by the First
Supplemental Indenture, dated as of April 3, 2001 (the indenture as so
supplemented, the "Indenture") providing for the issuance of an aggregate
principal amount of $225,000,000 of 8 5/8% Senior Subordinated Notes due 2013
(the "NOTES");

     WHEREAS, Section 4.13 of the Indenture provides that under certain
circumstances the Company is required to cause the Guarantor to execute and
deliver to the Trustee a supplemental indenture pursuant to which the Guarantor
shall unconditionally guarantee all of the Company's obligations under the Notes
pursuant to a Subsidiary Guarantee on the terms and conditions set forth herein;
and

     WHEREAS, pursuant to Section 9.1 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guarantor and the Trustee mutually covenant and agree for the equal and ratable
benefit of the Holders of the Notes as follows:

     1. CAPITALIZED TERMS. Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

     2. AGREEMENT TO GUARANTEE. The Guarantor hereby agrees that its
obligations to the Holder and the Trustee pursuant to this Subsidiary
Guarantee shall be as expressly set forth in Article XII of the Indenture and
in such other provisions of the Indenture as are applicable to the Guarantors
(including, without limitation, Article XIII of the Indenture), and reference
is made to the Indenture for the precise terms of this Supplemental
Indenture. The terms of Article XII of the Indenture and such other
provisions of the Indenture (including, without limitation, Article XIII of
the Indenture) as are applicable to the Guarantors are incorporated herein by
reference.

     3. EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEES

          (a) If an Officer whose signature is on this Supplemental Indenture
     no longer holds that office at the time the Trustee authenticates the Note,
     the Subsidiary Guarantee shall be valid nevertheless.

          (b) The delivery of any Note by the Trustee, after the authentication
     thereof under the Indenture, shall constitute due delivery of the
     Subsidiary Guarantee set forth in this Supplemental Indenture on behalf of
     the Guarantor.


     4. NO RECOURSE AGAINST OTHERS. No past, present or future director,
officer, employee, incorporator, stockholder of the Guarantor, as such, shall
have any liability for any obligations of the Company or any Guarantor under the
Notes, any Subsidiary Guarantee, the Indenture or this Supplemental 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
issuance of the Notes.

     5. NEW YORK LAW TO GOVERN. The internal law of the State of New York shall
govern and be used to construe this Supplemental Indenture and the Subsidiary
Guarantee.

     6. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

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


                                      -2-



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

Dated:   _______________, _______
                                         [Guarantor]


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


Dated:   _______________, _______
                                         The Bank of New York


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



                                      -3-