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                                                                    EXHIBIT 99.4

                       CERTIFICATION OF NON-FOREIGN STATUS

                         FOR PARTNERS THAT ARE ENTITIES

     Section 1446 of the Internal Revenue Code provides that a partnership must
pay a withholding tax to the Internal Revenue Service with respect to a
partner's allocable share of the partnership's effectively connected taxable
income, if the partner is a foreign person. To inform                    (insert
name of partnership) that the provisions of section 1446 do not apply, the
undersigned hereby certifies on behalf of                                (insert
name of partner that is an entity) ("Partner") the following:

     1. Partner is not a foreign corporation, foreign partnership, foreign
trust, or foreign estate (as those terms are defined in the Internal Revenue
Code and Income Tax Regulations);

     2. Partner's U.S. employer identification number is ______________________;
and


     3. Partner's office address is:

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

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

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

     Partner hereby agrees to notify the partnership within sixty (60) days of
the date Partner becomes a foreign person. Partner understands that this
certification may be disclosed to the Internal Revenue Service by the
partnership and that any false statement contained herein could be punished by
fine, imprisonment, or both.

     Under penalties of perjury I declare that I have examined this
certification and to the best of my knowledge and belief it is true, correct,
and complete, and I further declare that I have authority to sign this document
on behalf of Partner.

     Executed this   day of      , 2001.

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


                            IMPORTANT TAX INFORMATION

         PLEASE COMPLETE THIS CERTIFICATION, OR THE ATTACHED CERTIFICATION OF
NON-FOREIGN STATUS FOR PARTNERS THAT ARE INDIVIDUALS, AS APPROPRIATE, TO AVOID
FEDERAL INCOME TAX WITHHOLDING UNDER SECTION 1446 OF THE INTERNAL REVENUE CODE
ON YOUR LIMITED PARTNERSHIP INCOME AND DISTRIBUTIONS, INCLUDING THE PIONEER
COMMON STOCK AND CASH TO BE PAID TO YOU UPON THE MERGER OF EACH PARTNERSHIP IN
WHICH YOU OWN AN INTEREST.