PARKER & PARSLEY 83-A LTD

Q: Sep 30 2001

Q: Jun 30 2001

Q: Mar 31 2001

FY: Dec 31 2000

Q: Sep 30 2000

Q: Jun 30 2000

Q: Mar 31 2000

FY: Dec 31 1999

Q: Sep 30 1999

Q: Jun 30 1999

Q: Mar 31 1999

FY: Dec 31 1998

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FY: Mar 27 1998

Q: Sep 30 1997

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Q: Mar 31 1997

FY: Dec 31 1996

2

4

4

Certification of termination of registration of a class of securities (Section 12(g))

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

PIONEER NATURAL RESOURCES CO

PIONEER NATURAL RESOURCES CO

PIONEER NATURAL RESOURCES USA INC