аЯрЁБс;ўџ ўџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ§џџџџџџџ ўџџџўџџџўџџџ ўџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџRoot Entryџџџџџџџџџџџџўџџџџџџџџџџџџџџџўџџџџџџџџџџџџџџџўџџџџџџџџџџџџџџџўџџџ ЛЬсАСт\pCalc BАaР= œЏМ=@ 8X@"Зк1мCalibri1ШџArial1ШџArial1ШџArial1мМCalibri ЄGeneral Ѕ#,##0І#,##0.00рЄѕџ Р рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рѕџ єР рЄ Р р+ѕџ №Р р)ѕџ №Р р,ѕџ №Р р*ѕџ №Р р ѕџ №Р рЄ Р рЅ Р рЄ(8Р рЄ Р рІ Р рЄ(Р рЄ(8Р “€џ“€џ“€џ“€џ“€џ“€џ`…ЋTable…"]pioneer natural resources …"Йamendment number 1 to the …"‡ chief executive officer ce…$н#chief executive officer ce-1…$ѕ&chief executive officer ce-2…$M)chief executive officer ce-3…$Я+chief executive officer ce-4… k.pursuant to 18 usc 1350…"%1pursuant to 18 usc 1350-1ŒССTыЂ№š№`(   3 №П Р@@ё їќІA5Delaware 75-2702753(State or other jurisdiction of(I.R.S. Employerincorporation or organization)Identification No.)05205 N. O’Connor Blvd., Suite 900, Irving, Texas((Address of principal executive offices) (Zip Code)T Pioneer Natural Resources Company Form 10-K/A For the Year Ended December 31, 20043.3(a)-2Amendment No. 1 to Restated Bylaws of the Company.31.1(a)ZChief Executive Officer certification under Section 302 of the Sarbanes-Oxley Act of 2002.31.2(a)ZChief Financial Officer certification under Section 302 of the Sarbanes-Oxley Act of 2002.32.1(b)ZChief Executive Officer certification under Section 906 of the Sarbanes-Oxley Act of 2002.32.2(b)ZChief Financial Officer certification under Section 906 of the Sarbanes-Oxley Act of 2002.S AMENDMENT NUMBER 1 TO THE RESTATED BYLAWS OF PIONEER NATURAL RESOURCES COMPANY/s/ Larry N. Paulsen%Larry N. Paulsen, Assistant Secretary& CHIEF EXECUTIVE OFFICER CERTIFICATIONbI have reviewed this annual report on Form 10-K, as amended, of Pioneer Natural Resources Company;&Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of circumstances under which such statements were made, not misleading with respect to the period covered by this report;Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;DThe registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:(a)nDesigned such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;(b)gDesigned such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and(d)wDisclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; andЊAny fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.March 10, 2005/s/ Scott D. Sheffield9Scott D. Sheffield, Chairman and Chief Executive Officer/s/ Richard P. Dealy*Richard P. Dealy, Executive Vice Presidentand Chief Financial Officer PURSUANT TO 18 U.S.C. Ї 1350Name: Scott D. Sheffield, Chairman andChief Executive OfficerDate:March 10, 2005 Richard P. Dealy, Executive Vice%President and Chief Financial Officerџ 5т cc ЛЬ d-Cыт6?_€%,С*+‚ƒ„&ffffffц?'ffffffц?(ш?)ш?Ё"d,, Ж` Ж`р? Ж` Ж`р?U} Т0} А} Л} А,,,,,§ § § § § § § ~ ~”§ § ьP№H№№0№( № №>Ж@<dggџџџџ ЛЬ d-Cыт6?_€%,С*+‚ƒ„&ffffffц?'ffffffц?(ш?)ш?Ё"d,, Ж` Ж`р? Ж` Ж`р?U} Й} А} З} А} ЮZ} А ,@,,,,,§  О§  §  §  § §  § § §  § § §  § § §  § х ьP№H №№0№( № №>Ж@<dggџџџџ ЛЬ d-Cыт6?_€%,С*+‚ƒ„&ffffffц?'ffffffц?(ш?)ш?Ё"d,, Ж` Ж`р? Ж` Ж`р?U} А ,@,,,,,§ ОО § О § О О Ох2ьP№H0№ №0№( № № >Ж@<dggџџџџ ЛЬ d-Cыт6?_€%,С*+‚ƒ„&ffffffц?'ffffffц?(ш?)ш?Ё"d,, Ж` Ж`р? Ж` Ж`р?U} А} Й } гd} А ,@,,,,,, ,§ О~ § О~  § О~ § О~ § х"ьP№H@№№0№( № №>Ж@<dggџџџџ ЛЬ d-Cыт6?_€%,С*+‚ƒ„&ffffffц?'ffffffц?(ш?)ш?Ё"d,, Ж` Ж`р? 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