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EXHIBIT 99.12

FREQUENTLY ASKED QUESTIONS
REGARDING THE PROPOSED MERGERS OF THE
PARKER & PARSLEY LIMITED PARTNERSHIPS
(for use in responding to telephone inquiries only)

Q1: WHO IS PIONEER NATURAL RESOURCES COMPANY?

A: Pioneer is a large independent oil and natural gas exploration and
production company with operations in the United States, Canada,
Argentina, South Africa, Gabon and Tunisia. Pioneer's headquarters are
in Dallas, Texas.

Q2: WHEN WAS PIONEER FORMED?

A: Pioneer was created on August 7, 1997 through a merger of Parker &
Parsley Petroleum Company and MESA Inc.

Parker & Parsley was a Midland, Texas oil and gas company whose
predecessors began operations in the early 1960's. Parker & Parsley was
known for its successful development programs and its growth through
acquisitions.

MESA Inc. began in Amarillo, Texas and later moved to Irving, Texas.
The oil and gas company that was founded by Boone Pickens began
operations in 1964. MESA Inc. was known for its premier natural gas
properties in the U.S., characterized by long lived reserves and
stable, low-cost production.

Q3: WHERE ARE PIONEER'S SHARES TRADED?

A: Pioneer's common stock trades on the New York Stock Exchange and the
Toronto Stock Exchange under the ticker symbol "PXD".

Q4: HOW CAN I FIND PIONEER'S STOCK QUOTES IN MY LOCAL NEWSPAPER?

A: Pioneer trading activity should be listed alphabetically in the New
York Stock Exchange listings of your newspaper. Although newspapers
differ in the way they abbreviate Pioneer Natural Resources, common
abbreviations are "PIONR NAT RES", "PIONEER NATL", and "PION NATL".

Q5: DOES PIONEER PAY DIVIDENDS? (SEE PAGE 23 OF THE PROSPECTUS)

A: No.

Q6: WHY DOESN'T PIONEER PAY DIVIDENDS?

A: The last dividend Pioneer made to its shareholders was a five cent per
share dividend paid in September 1998. In January 1999 Pioneer's Board
of Directors voted to eliminate the $0.05 stock dividend it had
previously paid semi-annually, partly because the administrative cost
of paying this nominal dividend exceeded $200,000 per year and also
because the Company believed the funds would be used better to reduce
Company debt and invest in exploration and development activities.

Q7: CAN I PURCHASE STOCK DIRECTLY THROUGH PIONEER?

A: Pioneer does not offer a direct stock purchase plan except to its
employees. All stock purchases should be handled through a stock
brokerage firm of your choice.

Q8: I'M A SMALL SHAREHOLDER. CAN THE COMPANY PURCHASE MY SHARES FROM ME?

A: Pioneer does not have a program to allow holders of small numbers of
shares (fewer than 100) to sell their shares to the company directly.

Holders of 100 or more shares of Pioneer Natural Resources Company
stock may sell their shares through any stock brokerage firm. From time
to time other institutions have made odd-lot tender offers to our
stockholders to acquire holdings of fewer than 100 shares. If a third
party were to do one of these after the merger, you would get a notice
by mail from that other person. Pioneer does not currently plan to buy
back odd-lots itself.

Q9: WHO IS PIONEER'S TRANSFER AGENT FOR COMMON STOCK?

<Table>

A: Continental Stock Transfer & Trust Company Toll-free phone: 1-888-509-5586
2 Broadway, 19th Floor 1-212-509-4000
New York, NY 10004

Beginning late November 2001 (Telephone numbers will not change)
Continental Stock Transfer & Trust Company Toll-free phone: 1-888-509-5586
17 Battery Place, 8th Floor 1-212-509-4000
New York NY 10004
</Table>

Q10: I NEED TO CHANGE THE CURRENT REGISTRATION OF MY ACCOUNT DUE TO A DEATH,
THE ESTABLISHMENT OF A TRUST, A CHANGE OF IRA/KEOGH CUSTODIAN, A RECENT
MARRIAGE OR DIVORCE, ETC.

A: If the plan of merger is approved, and after receipt of stock
certificates issued as ownership is currently registered, contact the
stock transfer agent for common stock, Continental Stock Transfer &
Trust Company, 2 Broadway, 19th Floor, New York, NY 10004. Toll-free
phone: 1-888-509-5586.

After the vote is tallied and if the merger is not approved, contact
the limited partnership transfer agent in writing: Parker & Parsley
Limited Partnerships Transfer Agent, P.O. Box 3178, Midland, TX
79702-3178.

Q11: I OWN UNITS IN PARKER & PARSLEY LIMITED PARTNERSHIP XXX. IS THIS
LIMITED PARTNERSHIP INCLUDED IN THE PROPOSED MERGER? (SEE PAGES 77-78
OF THE PROSPECTUS)

A: Yes. All of the Parker & Parsley Limited Partnerships are included.

Q12: WHAT ARE THE TAX CONSEQUENCES OF THE PARKER & PARSLEY LIMITED
PARTNERSHIP MERGER? (SEE PAGES 8-9 OF THE SUMMARY IN THE PROSPECTUS AND
PAGES 54-57 OF THE PROSPECTUS)

A: The merger will be a taxable transaction. You will generally recognize
gain or loss equal to the difference between (1) the value of the
Pioneer Natural Resources Company stock you receive in the merger and
(2) your adjusted tax basis in the partnership interests. Your gain or
loss will be capital or ordinary depending on the nature of the assets
held in the partnership and the amount of depletion and intangible
drilling and development costs that must be recaptured. Tax matters are
complicated, and we suggest you consult a tax advisor to determine the
tax consequences to you. The merger will eliminate the limited
partners' schedule K-1 tax reports for years after 2001, which should
simplify your tax return preparation and reduce preparation costs.

Q13: WHAT SHOULD I USE AS MY TAX/COST BASIS? (SEE PAGES 54-57 OF THE
PROSPECTUS)

A: We suggest you read pages 54-57 of the prospectus and consult your own
tax advisor, since this basis may differ from person to person.

Q14: WHAT DOES "UNAFFILIATED PARTNER" MEAN?

A: It means a limited partner who is not Pioneer USA, its officers,
directors, or parent company, Pioneer Natural Resources Company.

Q15: HOW CAN I FIND THE VALUE OF MY LIMITED PARTNERSHIP AND/OR NUMBER OF
PIONEER SHARES I WOULD RECEIVE IN THE MERGER? (SEE PAGES 4-5 OF THE
PROSPECTUS)

A: Merger values are listed on pages 4 and 5 of the prospectus and on page
2 of the supplement for your partnership. The chart of merger values
also includes an estimated number of shares* to be issued based on each
$1,000 investment, based on an $18.00 per share price. The tables in
Appendix A also provide details about some of the components of the
merger value.
(See pages 49-52 of prospectus for more detail about how the merger
value was determined.)

* The stock price used in the calculation will be the average closing
price of PXD as reported by the New York Stock Exchange for the ten
trading days ending three business days before the date of the special
meeting.

Prior to the date of the special meeting for each partnership, we will
update the number of shares to be issued using the actual closing price
of Pioneer common stock for the ten trading days ending three business
days before the initial date of the special meeting. You may call D.F.
King & Co., Inc. after (date) at (800) 848-2998 to learn the final
number of shares you will receive if your partnership approves the
merger.

Q16: HOW CAN I CALCULATE THE NUMBER OF SHARES TO BE RECEIVED IN EXCHANGE FOR
MY LIMITED PARTNERSHIP UNITS? (SEE PAGE 6 OF THE PROSPECTUS.)

A: Page 6 of the prospectus gives an example of the calculation.
Basically, you divide the merger value per $1,000 initial limited
partner investment by the share price. Remember that the number of
shares to be issued will be based on a price equal to the average
closing price of the common stock for the ten trading days that end
three business days before the special meetings.

Q17: WHAT HAPPENS IF I DON'T VOTE? (SEE PAGES v AND 66-67 OF THE
PROSPECTUS.)

A: If there is no response from an investor, it is considered a "NO" vote.
If an investor returns a signed but not voted card, it is considered a
"YES" vote. A signed proxy card marked "ABSTAIN" is counted as present
for purposes of establishing a quorum, but it will not be voted, so it
will have the same effect as a vote against the merger.

Q18: I OWE MONEY TO PIONEER ON A NOTE ON A PARKER & PARSLEY LIMITED
PARTNERSHIP PRIVATE FUND. HOW DOES THIS AFFECT MY MERGER VALUE? (SEE
PAGES 10 AND 57 OF THE PROSPECTUS)

A: Pioneer will apply the common stock that would have otherwise been
issued to the limited partner in the merger to reduce the indebtedness
by the investor. If the indebtedness is less than the investor's merger
value, the limited partner will receive Pioneer Natural Resources
Company common stock for the remaining value after payment of
indebtedness.

If the limited partner's indebtedness to Pioneer USA is greater than
their merger value, Pioneer USA may collect the deficiency from the
limited partner.

Q19: WHY IS THE MERGER A GOOD DEAL FOR ME? (SEE PAGES 7-8, 34-37, 75-76 OF
THE PROSPECTUS.)

A Liquidity; provides an oil and gas investment vehicle; merger value
equal to or greater than liquidation value; provides acceleration of
realization of value; eliminates partnership tax reports; tax
incentives have been realized.

Q20: WHAT ARE THE DISADVANTAGES FOR ME IF THE MERGER OCCURS? (SEE PAGES 8
AND 20-26 OF THE PROSPECTUS.)

A Owning common stock in a corporation is a fundamental change in the
nature of the investment; there are market risks attendant to an
investment in a public company; you will have to sell stock if you want
to receive cash since the company does not plan to pay dividends; tax
considerations; and others.

Q21: WHAT IS THE REASON FOR THE CERTIFICATION OF NON-FOREIGN STATUS? (SEE
PAGE 9 OF THE PROSPECTUS.)

A: We are required by law to withhold federal income taxes from the common
stock of Pioneer Natural Resources Company that you will receive in the
merger, unless you certify to us that you are a U.S. person as defined
in the Certification of Non-Foreign Status. Your certificate must
include your taxpayer ID number and address and be properly signed.
You will be able to credit any amounts we withhold against your U.S.
federal income tax liability. If you do not otherwise file reports and
pay U.S. federal income taxes, you will not be able to recover the
withheld amounts.

Q22: WILL I RECEIVE A SEPARATE STOCK CERTIFICATE FOR EACH LIMITED
PARTNERSHIP THAT I OWN?

A No, you will receive one certificate reflecting the number of shares
due from all of your partnerships.

Q23: HOW SHOULD THE PROXY CARD BE SIGNED IF

a) THERE IS JOINT OWNERSHIP (both owners should sign)

b) THE OWNER IS DECEASED (executor/administrator, etc. should sign)

c) MY NAME HAS CHANGED (sign with name printed on proxy card.)

Q24: HOW WILL I KNOW THE OUTCOME OF THE VOTE?

A There will be a news release issued announcing the partnerships that
voted to merge. If you receive a check for cash distributions after the
meeting date, you will know that your partnership did not approve the
merger. If you receive stock, you will know that it did approve the
merger.

Q25: WHERE DO I SEND MY LIMITED PARTNERSHIP CERTIFICATES FOR EXCHANGE? (SEE
PAGE VI OF THE PROSPECTUS.)

A If a merger is completed, your certificates in that partnership will be
cancelled without further action by you. You will be mailed a
certificate of Pioneer common stock issued in your name.

Q26: WHO CAN I CONTACT IF I HAVE ADDITIONAL QUESTIONS OR IF I WANT MORE
INFORMATION ON PIONEER, SUCH AS ANNUAL REPORT, COPIES OF FORMS 10-K OR
10-Q?

A Contact Pioneer's Investor Relations department at (972) 969-3584 or
(972) 969-3583. Please also see "Where You Can Find More Information"
on pages beginning on the inside front cover of the prospectus.