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                                                                    EXHIBIT 99.6

            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9

    GUIDELINES FOR DETERMINING THE PROPER IDENTIFICATION NUMBER TO GIVE THE
PAYER.--Social Security numbers have nine digits separated by two hyphens: I.E.
000-00-0000. Employer identification numbers have nine digits separated by only
one hyphen: 00-00000000. The table below will help determine the number to give
the payer.

<Table>
<Caption>
- --------------------------------------------------
                       
                          GIVE THE
                          SOCIAL
                          SECURITY
FOR THIS TYPE OF ACCOUNT  NUMBER OF
- --------------------------------------------------

1. An individual's        The individual
   account

2. Two or more            The actual owner of the
   individuals (joint     account or, if combined
   account)               funds, the first
                          individual on the
                          account(1)

3. Husband and wife       The actual owner of the
   (joint account)        account or, if joint
                          funds the first
                          individual on the
                          account(1)

4. Custodian account of   The minor(2)
   a minor (Uniform Gift
   to Minors Act)

5. Adult and minor        The adult or, if the
   (joint account)        minor is the only
                          contributor, the
                          minor(1)

6. Account in the name    The ward, minor, or
   of guardian or         incompetent person(3)
   committee for a
   designated ward,
   minor, or incompetent
   person

7. a. The usual           The actual owner(1)
      revocable savings
      trust account
      (grantor is also
      trustee

  b. So-called trust      The actual owner(1)
     account that is not
     a legal or valid
     trust under State
     law

8. Sole proprietorship    The owner(4)
   account

<Caption>
- --------------------------------------------------
                          GIVE THE
                          EMPLOYER
                          IDENTIFICATION
FOR THIS TYPE OF ACCOUNT  NUMBER OF
- --------------------------------------------------
                       

 9. A valid trust,        The legal entity (Do not
    estate or pension     furnish the identifying
    trust                 number of the personal
                          representative or
                          trustee unless the legal
                          entity itself is not
                          designated in the
                          account title.)(5)

10. Corporate account     The corporation

11. Religious,            The partnership
    charitable held in
    the name of the
    partnership

12. Partnership account   The partnership
    held in the name of
    the partnership

13. Association, club,    The organization
    or other tax-exempt
    organization

14. A broker or           The broker or nominee
    registered nominee

15. Account with the      The public entity
    Department of
    Agriculture in the
    name of a public
    entity (such as a
    State or local
    government, school
    district or prison)
    that receives
    agricultural program
    payments
</Table>

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

(1) List first and circle the name of the person whose number you furnish.

(2) Circle the minor's name and furnish the minor's social security number.

(3) Circle the ward's, minor's or incompetent person's name and furnish such
    person's social security number.

(4) You must show your individual name, but you may also enter your business or
    "doing business" name. You may use either your Social Security Number or
    Employer Identification Number.

(5) List first and circle the name of the legal trust, estate, or pension trust.

NOTE:  If no name is circled when there is more than one name, the number will
       be considered to be that of the first name listed.
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                         NUMBER ON SUBSTITUTE FORM W-9
                                     PAGE 2

OBTAINING A NUMBER

    If you do not have a taxpayer identification number, obtain Form SS-5,
Application for Social Security Card, or Form SS-4, Application for Employer
Identification Number, at the local office of the Social Security Administration
or the Internal Revenue Service (the "IRS") and apply for a number.

    Payees specifically exempted from backup withholding on ALL payments by
brokers include the following:

    - A corporation.

    - A financial institution.

    - An organization exempt from tax under Section 501(a), or an individual
      retirement plan or a custodial account under Section 403(b)(7) if the
      account satisfied the requirements of Section 401(f)(2).

    - The United States or any agency or instrumentality thereof.

    - A State, the District of Columbia, a possession of the United States, or
      any subdivision or instrumentality thereof.

    - A foreign government, a political subdivision of a foreign government, or
      any agency or instrumentality thereof.

    - An international organization or any agency or instrumentality thereof.

    - A registered dealer in securities or commodities registered in the U.S. or
      a possession of the U.S.

    - A real estate investment trust.

    - A common trust fund operated by a bank under Section 584(a).

    - An entity registered at all times under the Investment Company Act of
      1940.

    - A foreign central bank or issue.

    - A futures commission merchant registered with the Commodity Futures
      Trading Commission.

    - A person registered under the Investment Advisors Act of 1940 who
      regularly acts as a broker.

    Payments of dividends and patronage dividends not generally subject to
backup withholding include the following:

    - Payments to nonresident aliens subject to withholding under Section 1441.

    - Payments to partnerships not engaged in a trade or business in the U.S.
      and which have at least one nonresident partner.

    - Payments of patronage dividends where the amount received is not paid in
      money.

    - Payments made by certain foreign organizations.

    - Payments made to a nominee.

    Payments of interest not generally subject to backup withholding include the
following:

    - Payments of interest on obligations issued by individuals. Note: You may
      be subject to backup withholding if this interest is $600 or more and is
      paid in the course of the payer's trade or business and you have not
      provided your correct taxpayer identification number to the payer.

    - Payees specifically exempted from backup withholding on ALL payments by
      brokers include the following:

    - Payments described in Section 6049(b)(5) to nonresident aliens.

    - Payments on tax-free covenant bonds under Section 1451.

    - Payments made by certain foreign corporations.

    - Payments made to a nominee.

    EXEMPT PAYEES DESCRIBED ABOVE SHOULD FILE FORM W-9 TO AVOID POSSIBLE
ERRONEOUS BACKUP WITHHOLDING. FILE THIS FORM WITH THE PAYER, FURNISH YOUR
TAXPAYER IDENTIFICATION NUMBER, CHECK "EXEMPT" IN PART II OF THE FORM, SIGN AND
DATE THE FORM AND RETURN IT TO THE PAYER.

    Certain payments other than interest, dividends, and patronage dividends,
which are not subject to information reporting are also not subject to backup
withholding. For details, see the regulations under Section 6041, 6041(A)(a),
6045, and 6050A.

    PRIVACY ACT NOTICE.--Section 6109 requires most recipients of dividend,
interest, or other payments to give taxpayer identification numbers to payers
who must report the payments to IRS. IRS uses the numbers for identification
purposes. Payers must be given the numbers whether or not recipients are
required to file tax returns. Beginning January 1, 1993, payers must generally
withhold 31% of taxable interest, dividend, and certain other payments to a
payee who does not furnish a taxpayer identification number to a payer. Certain
penalties may also apply.

PENALTIES

(1) PENALTY FOR FAILURE TO FURNISH TAXPAYER IDENTIFICATION NUMBER.--If you fail
    to furnish your taxpayer identification number to a payer, you are subject
    to a penalty of $50 for each such failure unless your failure is due to
    reasonable cause and not to willful neglect.

(2) CIVIL PENALTY FOR FALSE INFORMATION WITH RESPECT TO WITHHOLDING.--If you
    make a false statement with no reasonable basis that results in no
    imposition of backup withholding, you are subject to a penalty of $500.

(3) CRIMINAL PENALTY FOR FALSIFYING INFORMATION.--Falsifying certifications or
    affirmations may subject you to criminal penalties including fines and/or
    imprisonment.

         FOR ADDITIONAL INFORMATION CONTACT YOUR TAX CONSULTANT OR THE
                           INTERNAL REVENUE SERVICE.