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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 Pioneer Natural Resources
USA, Inc., the general partner of the Parker & Parsley limited partnerships,
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
PARENT COMMON STOCK TO BE PAID TO YOU UPON THE MERGER OF EACH PARTNERSHIP IN
WHICH YOU OWN AN INTEREST.