1
 
                                                                    EXHIBIT 99.6
 
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9
 
     GUIDELINES FOR DETERMINING THE PROPER IDENTIFICATION NUMBER TO GIVE
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: i.e. 00-0000000. The table below will help determine the number to
give the payer.
 

                                                  
FOR THIS TYPE OF ACCOUNT:                            GIVE THE NAME AND SOCIAL SECURITY NUMBER OF:
 
 1. An individual's account                          The individual

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

 3. Husband and wife (joint account)                 The actual owner of the account or, if joint funds, either
                                                     person(1)

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

 5. Adult and minor (joint account)                  The adult or, if the minor is the only contributor, the
                                                     minor(3)

 6. Account in the name of guardian or committee     The ward, minor, or incompetent person(4)
    for a designated ward, minor, or incompetent
    person

 7. a. The usual revocable savings trust account     The grantor-trustee(3)
       (grantor is also trustee)

    b. So-called trust account that is not a legal   The actual owner(3)
       or valid trust under State law
 
FOR THIS TYPE OF ACCOUNT:                            GIVE THE NAME AND EMPLOYER IDENTIFICATION NUMBER OF:
 
 8. Sole proprietorship account                      The owner(5)

 9. A valid trust, estate, or pension trust          Legal entity (Do not furnish the identifying number of the
                                                     personal representative or trustee unless the legal entity
                                                     itself is not designated in the account title.)(3)

10. Corporate account                                The corporation

11. Religious, charitable, or educational            The organization
    organization account

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

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

14. A broker or registered nominee                   The broker or nominee

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

 
- ---------------
(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) List first and circle the name of the legal trust, estate, or pension trust.
 
(4) Circle the ward's, minor's or incompetent person's name and furnish such
    person's social security number.
 
(5) Show the name of the owner.
 
 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.
   2
 
            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9
 
OBTAINING A NUMBER
 
    If you don't have a TIN or you don't know your number, obtain Internal
Revenue Service Form SS-5, Application for a Social Security Number Card, or
Form SS-4, Application for Employer Identification Number, at your local office
of the Social Security Administration or the Internal Revenue Service and apply
for a number.
 
PAYEES EXEMPT FROM BACKUP WITHHOLDING
 
    Payees specifically exempted from backup withholding on ALL payments include
the following:
 
    (1) A corporation.
 
    (2) A financial institution.
 
    (3) An organization exempt from tax under section 501(a) or an individual
        retirement plan.
 
    (4) The United States or any agency or instrumentality thereof.
 
    (5) A State, the District of Columbia, a possession of the United States, or
        any subdivision or instrumentality thereof.
 
    (6) A foreign government, a political subdivision of a foreign government,
        or any agency or instrumentality thereof.
 
    (7) An international organization or any agency, or instrumentality thereof.
 
    (8) A registered dealer in securities or commodities registered in the U.S.
        or a possession of the U.S.
 
    (9) A real estate investment trust.
 
    (10) A common trust fund operated by a bank under section 584(a).
 
    (11) An exempt charitable remainder trust, or a non-exempt trust described
         in section 4947(a)(1).
 
    (12) An entity registered at all times under the Investment Company Act of
         1940.
 
    (13) A foreign central bank of issue.
 
    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.
 
    - Payments of tax-exempt interest (including exempt-interest dividends under
      section 852).
 
    - Payments described in section 6049(b)(5) to nonresident aliens.
 
    - Payments on tax-free covenant bonds under section 1451.
 
    - Payments made by certain foreign organizations.
 
    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, WRITE "EXEMPT" ON THE FACE OF THE FORM, AND
RETURN IT TO THE PAYER. IF THE PAYMENTS ARE INTEREST, DIVIDENDS, OR PATRONAGE
DIVIDENDS, ALSO SIGN AND DATE THE FORM.
 
    Certain payments other than interest, dividends, and patronage dividends,
that are not subject to information reporting are also not subject to backup
withholding. For details, see the regulations under sections 6041, 6041A(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. 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) FAILURE TO REPORT CERTAIN DIVIDEND AND INTEREST PAYMENTS--If you fail to
    include any portion of an includible payment for interest, dividends, or
    patronage dividends in gross income, such failure will be treated as being
    due to negligence and will be subject to a penalty of 5% on any portion of
    an under-payment attributable to that failure unless there is clear and
    convincing evidence to the contrary.
 
(3) CIVIL PENALTY FOR FALSE INFORMATION WITH RESPECT TO WITHHOLDING--If you make
    a false statement with no reasonable basis which results in no imposition of
    backup withholding, you are subject to a penalty of $500.
 
(4) 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.