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                       PERFORMANCE ENGINEERING CORPORATION
                         NONQUALIFIED STOCK OPTION PLAN

         1.       PURPOSE OF PLAN.

                  The purposes of this Performance Engineering Corporation
("Corporation") Nonqualified Stock Option Plan are to further enable the
Corporation to continue to attract and retain the most qualified employees and
outside Directors and to further the growth, development and financial success
of the Corporation.

         2.       TERM OF THE PLAN AND AWARDS.

                  (a) TERM OF THE PLAN. The Plan shall continue in effect for a
period of ten (10) years from its Effective Date of January 1, 1995. Unless this
Plan is extended, no further options shall be granted hereunder after such date.

                  (b) TERM OF AWARDS. The term of each option award shall be as
specified by the Committee, subject to earlier termination as provided in
Paragraphs 7 and 8 hereof, but shall not exceed ten (10) years.

         3.       SHARES SUBJECT TO THE PLAN.

                  Except as otherwise required by the provisions of Paragraph 10
hereof, the aggregate number of shares of the Corporation's common stock
deliverable pursuant to option awards shall not exceed 300,000 shares. Optioned
shares may either be authorized but unissued shares or shares held in treasury.
If option awards should expire, become unexercisable or be forfeited for any
reason without having been exercised in full, the option shares shall be
available for the grant of additional option awards under this Plan.

         4.       ADMINISTRATION OF THE PLAN.

                  (a) COMPOSITION OF THE COMMITTEE. This Plan shall be
administered by a Stock Option Committee ("Committee"), which shall be appointed
by the Board of Directors of the Corporation. In the absence at any time of a
duly appointed Committee, the Plan shall be administered by the entire Board of
Directors of the Corporation.

                  (b) POWERS OF THE COMMITTEE. The Committee shall have the sole
and absolute authority and discretion (i) to select participants and grant
option awards, (ii) to determine the form, content and timing of any option
award to be issued hereunder, (iii) to prescribe, amend and rescind rules and
regulations relating to the Plan, and (iv) to make all interpretations and
determinations necessary or advisable for the administration of the Plan.

                  (c) EFFECT OF THE COMMITTEE'S DECISIONS. All decisions,
determinations and interpretations of the Committee shall be final and
conclusive on all persons affected thereby.


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                  (d) INDEMNIFICATION. In addition to such other rights of
indemnification as they may have, the members of the Committee shall be
indemnified by the Corporation in connection with any claim, action, suit or
proceeding relating to any action taken or failure to act under or in connection
with the Plan or any option award granted hereunder to the full extent provided
for in the Corporation's Articles of Incorporation with respect to the
indemnification of directors.

         5.       EXERCISE PRICE FOR OPTIONS.

                  The exercise price for any option award granted hereunder
shall not be less than the market value of the optioned shares on the date of
grant, as determined by the Committee from time to time ("Annex I value").

         6.       EXERCISING OPTIONS.

                  (a) GENERALLY. Any option award granted hereunder shall be
exercisable according to its terms by giving written notice to the Corporation
specifying the option being exercised. An option award may be exercised only as
to the full number of shares granted therein.

                  (b) PAYMENT. The exercise price of the shares as to which an
option is exercised shall be paid in full at the time of exercise either in cash
or in shares of the Corporation, or by a combination of cash and shares.

                  (c) PERIOD OF EXERCISABILITY. Any option award granted
hereunder shall not be transferred or assigned in any manner and may be
exercised only if the grantee continues to serve as an employee or director of
the Corporation at the time of exercise.

         7.       TERMINATION OF STATUS WITH CORPORATION.

                  In the event that a grantee ceases to serve as an employee or
Director of the Corporation, other than for reasons of death, disability or
retirement at age 65 or later ("termination of status"), all unexercised options
shall immediately terminate. Nothing in the Plan or in any option award granted
hereunder shall confer upon any person any right to continue to serve as an
employee or Director of the Corporation.

                  In the event of termination of status, for any reason, of a
grantee who has exercised an option award to purchase shares of the Corporation
twelve (12) months or more prior to the termination of status, such shares are
required to be offered for sale to the Corporation by the grantee or personal
representative, at a price equal to the Annex I value as of the date of the
termination of status, in accordance with the terms contained in Section 3.3 of
the Attachment reproduced herein.


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<PAGE>

                  Should an exercise of an option award occur less than twelve
(12) months prior to the date of the termination of status, such shares are
required to be offered for sale to the Corporation at the exercise price paid
for said shares, in accordance with the terms contained in Section 3.3 of the
Attachment.

                  Closing on any sale to the Corporation shall take place within
thirty (30) days of the termination of status. Should the Corporation elect not
to purchase the offered shares, then the grantee shall be required to offer the
shares for sale to other stockholders under the terms set forth in Section 3.3
of the Attachment.

         8.       DEATH, RETIREMENT OR DISABILITY.

                  If a grantee to whom an option award is outstanding but not
exercised shall die, become disabled or retire at age 65 or thereafter, the
Corporation shall pay said grantee or his personal representative the difference
between the exercise price of the option award and the Annex I value for the
number of optioned shares at the date of death, disability or retirement. For
purposes of this paragraph, disability shall be defined as a condition rendering
the grantee unable to perform any of the material functions of his duties and
responsibilities to the Corporation for a continuous period of five (5) months.

         9.       AMENDMENT AND TERMINATION OF PLAN.

                  The Committee may from time to time amend the terms of the
Plan and, with respect to any shares not subject to option awards, suspend or
terminate the Plan. No amendment, suspension or termination of the Plan shall,
without the consent of any affected grantee of an option award, alter or impair
any rights or obligations under an outstanding option award.

         10.      ADJUSTMENTS UPON CHANGES OR CAPITALIZATIONS.

                  The number and kind of shares reserved for issuance under the
Plan, and the number and kind of shares subject to outstanding option awards and
the exercise price thereof, shall be proportionately adjusted for any increase,
decrease, change or exchange of shares for a different number or kind of shares
which results from a merger, consolidation, recapitalization, reorganization,
split up, stock split, stock dividend and the like. Any fractional shares
resulting from such adjustments shall be eliminated.

         11.      CONDITIONS UPON ISSUANCE OF SHARES.

                  (a) COMPLIANCE WITH SECURITIES LAWS. Shares of common stock
shall not be issued with respect to any award unless the issuance and delivery
of such shares shall comply with all relevant provisions of law, including,
without limitation, the Securities Act of 1933, as amended, the rules and
regulations promulgated thereunder, any applicable state securities law and the
requirements of any stock exchange upon which the shares may then be listed. The
Plan is intended to comply with Rule 16b-3, and any provision of the Plan which
the Committee determines in its sole and absolute discretion to be inconsistent
with said Rule shall, to the extent


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<PAGE>

of such inconsistency, be inoperative and null and void, and shall not affect
the validity of the remaining provisions of the Plan.

                  (b) COMPLIANCE WITH STOCKHOLDERS AGREEMENT. Any and all shares
acquired pursuant to the exercise of option awards granted hereunder shall be
and are specifically subject to the following restrictions from Performance
Engineering Corporation's Stockholders' Agreement, as amended.

                      1. Article III, Transfer of Shares (reprinted below).
                      2. Article IV, Miscellaneous Provisions (reprinted below).

                         ARTICLE III. TRANSFER OF SHARES

         3.1 TRANSFERS UPON DEATH OR DISABILITY OR RETIREMENT. Upon the earlier
of an Initial Stockholder's death or disability or retirement on or after age
65, the withdrawing Initial Stockholder or estate shall have an option to offer
for sale to the Corporation such Initial Stockholder's entire initial Stock
interest, as defined in Article I, INITIAL CAPITALIZATION, Section 1.1 INITIAL
ISSUANCE, hereof, at the price and terms described in Section 3.4. The
withdrawing Initial Stockholder or estate shall be permitted the period of one
hundred twenty (120) days from said death, retirement or determination of
disability to deliver his written request to the Corporation to purchase such
shares. The purchase, or commitment to purchase, as applicable, by the
Corporation, in accordance with the terms of Section 3.4 of said shares shall
take place within sixty (60) days of the delivery to the Corporation of the
written request. In no event shall any offer for sale obligate the Corporation
to accept such offer.

         The withdrawing Stockholder or estate shall be granted additional
option(s) to request that the Corporation purchase his entire initial Stock
interest, as defined in Article I, INITIAL CAPITALIZATION, Section 1.1 INITIAL
ISSUANCE, hereof, upon the occurrence of each additional or subsequent event of
withdrawal, defined for this purpose as death, disability or retirement on or
after age 65.

         This provision shall not apply to any shares acquired by any
Stockholder, Initial Stockholder or otherwise, by exercise of options granted
under the Performance Engineering Corporation Stock Option Agreement or the
Performance Engineering Corporation Nonqualified Stock Option Plan or any other
means. Disposition of said Stock shall be governed by Article 12 of said Stock
Option Agreement or Article 8 of the Nonqualified Stock Option Plan, whichever
is applicable.

         Disability of an Initial Stockholder shall be defined as total
disability under the terms of a Corporation-maintained insurance company
disability policy covering the withdrawing Initial Stockholder, or, if no such
policy exists, disability rendering the withdrawing Initial Stockholder unable
to perform any of the material functions of his employment with the Corporation
for a continuous period of five (5) months. The date of the occurrence of an
event of disability shall be the date of the first determination of total
disability made by the insurance company, if the Corporation has such a policy,
or the Board of Directors, if the Corporation does not.



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<PAGE>

         Upon the first occurrence of death, disability or retirement on or
after age 65, the nonwithdrawing Stockholders shall be released from any and all
obligations under this Agreement to continue the withdrawing Initial
Stockholder, or his representative, or successor, as a director and/or officer
of the Corporation, regardless of whether the withdrawing Initial Stockholder,
or his estate, exercises the option to offer the withdrawing Initial
Stockholder's entire Stock interest to the Corporation for purchase and
regardless of whether the Corporation purchases said Stock or portions thereof.

         3.2      TRANSFERS UPON TERMINATION FOR CAUSE. Any of the Initial
Stockholders or any other Stockholder may be terminated as a director and/or
employee of the Corporation for cause as determined by the majority of the
Stockholders or of the Board of Directors, as applicable according to the
election privileges accorded to each. For this purpose, cause shall be limited
to intentional malfeasance, repeated gross negligence resulting in significant
damage, loss or exposure to the Corporation or fraud committed by a Stockholder
in his capacity as an officer or employee of the Corporation or in his capacity
as a Stockholder with respect to his obligations to the other Stockholders under
this Agreement. If a Stockholder's employment is terminated for cause, such
Stockholder shall automatically be discharged as a Director and/or officer.

         Upon the termination of employment for cause of any Stockholder, said
Stockholder shall offer for sale to the Corporation and the Corporation shall
have the option to purchase his entire Stock interest at the price and terms
established in Section 3.4, except that, for such shares as were obtained
through Stock options, price and terms shall be established in accordance with
Article 10, TERMINATION OF EMPLOYMENT, of the Performance Engineering
Corporation Stock Option Agreement or with Article 7, TERMINATION OF STATUS WITH
CORPORATION, of the Performance Engineering Corporation Nonqualified Stock
Option Plan, whichever is applicable. Should the Corporation decline to purchase
all or any part of any Initial Stockholders' Initial shares hereunder, then such
shares shall be offered according to the sequence outlined in Section 3.3 below,
treating the Corporation's initial option to purchase as the first offering
thereunder. Closing of said purchase, or commitment to purchase, as may be
applicable under Section 3.4, shall take place within sixty (60) days of the
official written determination of termination for cause.

         3.3      RIGHT OF FIRST REFUSAL. If for any reason a Stockholder
desires to sell, transfer or otherwise dispose of any portion or all of his
Stock in the Corporation, he shall offer to sell such entire Stock interest or
portion thereof to the Corporation at a price and upon the terms determined in
accordance with the provisions of Section 3.4 of this Agreement; except that for
such shares as were obtained through Stock option exercise, price shall be
established in accordance with the second paragraph of Article 8, VOLUNTARY
SALE, of the Performance Engineering Corporation Stock Option Agreement or
Article 7, TERMINATION OF STATUS WITH CORPORATION, of the Performance
Engineering Corporation Nonqualified Stock Option Plan, whichever is applicable.
Any Stock not purchased by the Corporation within thirty (30) days after receipt
of such offer in writing shall then first be available at the same price and
terms to the other Stockholders, each of whom shall have the right, within ten
(10) days after the expiration of the Corporation's option to purchase, to
purchase such remaining Stock offered for sale in proportion to the ratio that
the number of shares owned by him on the date the offering Stockholder first
offered his Stock to the Corporation bears to the total number of shares of
Stock



                                       5
<PAGE>

owned by the Stockholders on such date, excluding the shares of Stock owned by
the offering Stockholder or Stockholders; provided, however, that if any
remaining Stockholder does not purchase his full proportionate share of the
Stock within ten (10) days, the offered Stock may, within five (5) days after
the expiration of said ten (10) day period, be purchased by the other remaining
Stockholders as they shall agree but, failing agreement, in equal shares. If
both the Corporation and the remaining Stockholders fail or refuse to purchase
the offered Stock of the offering Stockholder at the price and upon the terms
and within the times aforesaid, then the offering Stockholder shall offer the
remaining Stock to the non-Stockholder employees of the Corporation, each of
whom shall have the right, within ten (10) days after the expiration of the
Stockholders' option to purchase, to purchase such remaining Stock offered for
sale. If the Corporation, the remaining Stockholders and the employees fail or
refuse to purchase any or all of the offered Stock of the offering Stockholder
at the price and upon the terms and within the times aforesaid, then the
offering Stockholder shall be at liberty to offer his remaining offered Stock to
any other qualified third party (other than the remaining Stockholders), but the
offering Stockholder shall not sell such Stock to any third party without again
offering such Stock first to the Corporation and then to the remaining
Stockholders and employees as provided above, allowing the periods provided
above in each instance for the acceptance thereof, at the lower of (a) such
price and terms aforesaid or (b) at such price and terms offered to any
qualified third party. Prior to any sale of Stock by an offering Stockholder to
any non-Stockholder employee or to such qualified third party, the Corporation
must have received from its counsel the unqualified opinion of such counsel that
the proposed sale will not violate Federal and applicable state securities laws,
including any restrictions placed upon the public offering of such Stock.

         3.4      VALUATION AND PAYMENT. The valuation of the Stock of the
Corporation for purposes of establishing the purchase price to be paid for the
Stock of a Stockholder pursuant to Sections 3.1, 3.2 or 3.3 shall be the Annex I
value of the Stock, as determined by this section.

         Valuation of Stock acquired as a result of options exercised under the
Performance Engineering Corporation Stock Option Agreement or the Performance
Engineering Corporation Nonqualified Stock Option Plan shall be governed by said
Agreement. Such shares which are disposed of as a result of termination, death,
disability, retirement or choice thereunder shall be disposed of in accordance
with Article 8, Article 10 or Article 12 of the Stock Option Agreement, or
Article 7 or Article 8 of the Nonqualified Stock Option Plan, whichever is
applicable.

         The values set forth in Annex I shall be reviewed at least annually by
December 31 of each year or more frequently if agreed to by the board of
Directors. Any changes in such values must be made in a writing signed by all of
the Board of Directors.

         If such annual review does not take place or agreement as to change in
valuation cannot be reached, the effective new Annex I value shall be the last
value agreed upon increased by the rate of ten percent (10%) per full year, or
part thereof, from the date of such last agreement.

         Payment by the Corporation for the Stock of a Stockholder, whether
Stock shall have been acquired as Initial Shares or through options, or
otherwise, shall be as determined by this section.


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         The purchase price shall be evidenced by a negotiable promissory note
executed by the Corporation bearing interest at the rate of ten percent (10%)
per annum, requiring not more than sixty (60) equal monthly payments of
principal and interest, provided, however, that the minimum monthly payment may
not be less than $2,000.00, excluding final payments which may be less than
$2,000.00. Such note shall provide that, upon default in the payment of any
installment of interest or principal, all remaining installment payments shall,
at the option of the holder of said note, become immediately due and payable.
Said notice shall also give the Corporation the option of prepayment, in whole
or in part, at any time with no penalty. Upon the sale of the Stock to the
Corporation, the withdrawing Stockholder or estate shall be entitled to retain a
security interest in the Stock to secure payment of the Corporation's
obligation, which security interest shall be relinquished upon full payment for
all of the Stock to be purchased under this Agreement. This note shall not be
required, however, should the Corporation elect to pay the purchase price in
full on the date of closing as specified herein.

         Notwithstanding the foregoing, however, where such total payment of
principal and interest would exceed the amount of $240,000.00, the Corporation
shall have the option, in the sole discretion of the Board of Directors, to
phase such purchase over a period of between 72 and 120 months, to be phased in
increments of 12 months, under terms as follows: if such purchase option is
elected by the Board of Directors, the withdrawing Stockholder shall be
obligated by the terms of this Agreement to sell the Stock to the Corporation
annually over the period specified by the Corporation in increments of shares to
be determined by the Corporation for each 12-month period of sale, equal
payments to be made each month including interest at the rate of ten percent
(10%), calculated over the 12-month period, at the Annex I value in effect for
the beginning of each such 12-month period; in no case, however, shall payment
to the Stockholder for such Stock be less than $4,000.00 per month, excluding
final payments which may be less than $4,000.00. If at any time the total
payment due the Stockholder for any outstanding shares would exceed $240,000.00
as determined at the beginning of each new 12-month increment, the Corporation
may in its discretion elect a new phased purchase plan under the same terms and
conditions as if the new phased plan were the original election. Upon the sale
of each increment of the Stock to the Corporation, the withdrawing Stockholder
or estate shall be entitled to retain a security interest in that increment of
Stock, to secure payment of the Corporation's obligation, which security
interest shall be relinquished upon full payment for each increment of the Stock
to be purchased under this paragraph. For all Stock obligated to be sold by the
Stockholder under this paragraph but retained by him prior to sale, the
Stockholder shall retain full rights.

         3.5      CLOSING DATE. The closing of any purchase under this Agreement
shall take place at 1:00 o'clock p.m. on the day provided in this Agreement at
the offices of Performance Engineering Corporation, 3949 Pender Drive, Fairfax,
Virginia, or at such other time and place as shall be fixed by written agreement
of the parties hereto (the "Closing").

         At the Closing, the selling Stockholder or his personal representative
shall deliver to the Corporation or to the purchasing Stockholder, as the case
may be, certificates representing all of the Stock to be purchased, duly
endorsed, free and clear of all liens, claims or encumbrances,



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with evidence of payment of all transfer taxes and fees, if any. The Corporation
or the purchasing Stockholders, as the case may be, shall deliver to the selling
Stockholder or his personal representative the payment (by certified or
cashier's check) or the promissory note, as provided in Section 3.4. The
Corporation shall also deliver at Closing to the selling Stockholder or his
personal representative an appropriate release from any and all liabilities of
the Corporation, including any and all secondary liability with respect thereto
by way of personal guarantees of corporate indebtedness and any other
agreements. In connection with the Closing, the Corporation and all Stockholders
and their personal representatives, if any, shall do all things necessary to
accomplish the purchase and sale.

         If the selling Stockholder or his personal representative does not
tender the certificates for the shares of Stock to be purchased as provided
herein at the Closing, the Corporation shall cause the transfer books of the
Corporation to reflect that such shares of Stock have been canceled or
transferred, as the case may be, and the Corporation or the purchasing
Stockholders, as the case may be, shall tender to the selling Stockholder or his
personal representative the payment (by certified or cashier's check) or the
promissory note, as provided in Paragraphs (a) and (b) above. After the transfer
books of the Corporation have been so modified and after such tender of payment
has been made (whether or not accepted by the selling Stockholder, his estate or
his personal representative), neither the selling Stockholder, his estate nor
his personal representative shall be considered to own Stock in the Corporation
and shall have no rights under the terms of this paragraph.

         Each Stockholder hereby appoints the Corporation as his agent and
attorney-in-fact for the purpose of executing and delivering any and all
documents necessary to convey such Stockholder's Stock pursuant to the
provisions of this paragraph. In the event the Stockholder is not present at the
Closing, any conveyance by such agent and attorney-in-fact shall be a conveyance
of all of the Stockholder's right, title and equity in and to the Stock. This
power of attorney is coupled with an interest and shall not expire upon the
death or incapacity of a Stockholder, nor may this power of attorney be
terminated by any Stockholder as long as this Agreement remains in effect.

         3.6      LIFE INSURANCE. The Corporation shall have the right to
purchase insurance on the lives of any or all of the Stockholders to fund its
obligations under this Agreement. The Corporation agrees to pay premiums on said
insurance policies, if any, and shall provide proof of payment of premiums to
any Stockholder who requests such proof. If a premium is not paid within ten
(10) days after its due date, the insured shall have the right to pay such
premiums and be reimbursed therefor by the Corporation. In the event that the
Corporation decides to purchase life insurance on any Stockholder, each
Stockholder hereby agrees to cooperate fully by performing all of the
requirements of the insurer which are necessary conditions precedent to the
issuance of life insurance policies. The Corporation shall be the sole owner of
the policies issued to it and it may apply any dividends toward the payment of
premiums.

         Notwithstanding the provisions of this Agreement, any life insurance
company which has issued a policy of life insurance subject to the provisions of
this Agreement is hereby authorized to act in accordance with the terms of such
policy as if the Agreement did not exist, and the payment or other performance
of its contractual obligations required by any such policy shall



                                       8
<PAGE>

completely discharge such company from all claims, suits and demands of all
persons whomsoever.

         If, at any time after the death of a Stockholder, the Corporation shall
receive the proceeds from any insurance policy owned by the Corporation on the
life of the deceased Stockholder, the Corporation shall immediately use such
funds to prepay the installment payments owing to the estate or any beneficiary
of the deceased Stockholder, as provided in Section 3.1 hereof. If the
Corporation has elected not to purchase shares offered under Section 3.1 above,
and the Corporation subsequently receives such insurance proceeds, the
corporation shall then be obligated to purchase such shares up to the full
amount of the proceeds received, should an offer for sale be then current, using
such insurance proceeds as outlined in this paragraph above.

         3.7      TRANSFER IN VIOLATION OF THIS AGREEMENT. The Stockholders may
not, either singly or collectively, under any circumstances sell or transfer
their Stock in the Corporation other than in accordance with the terms of this
Agreement, and, for Stock acquired under the Performance Engineering Corporation
Stock Option Agreement or Nonqualified Stock Option Plan, whichever is
applicable, in additional accordance with the terms thereunder, nor may they
pledge, assign or otherwise encumber their Stock in the Corporation.

         In the event any Stockholder (hereinafter referred to as the "Offending
Stockholder") sells, assigns, transfers, gives, pledges, encumbers or otherwise
disposes of or grants a security interest in any of the Stock owned by him
otherwise than in strict accordance with the terms of this Agreement, then, in
addition to the right to any other remedies hereunder, including specific
performance, the Corporation shall have the option to purchase such Stock from
the person, trust, association, company, firm or corporation (the Transferee")
to whom such Stock has been sold, assigned, transferred, given, pledged,
encumbered or otherwise disposed of, for an amount, in cash, equal to the amount
paid by such Transferee for such Stock or fifty percent (50%) of the value of
such Stock, as determined under Section 3.4 hereof, whichever is less. The
payment of such purchase price shall be by certified or cashier's check at the
Closing described in the following paragraph.

         The Corporation may exercise the purchase option provided for in this
Section 3.7 by giving written notice to the Transferee of the Offending
Stockholder at any time within one year after the Corporation receives actual
notice of such sale, assignment, transfer, gift, pledge, encumbrance or other
disposition of Stock otherwise than in accordance with the provisions of this
Agreement or, for Stock acquired under the performance Engineering Corporation
Stock Option Agreement or Nonqualified Stock Option Plan, whichever is
applicable, in additional accordance with the terms thereunder. The Closing of
any purchase under this Section 3.7 shall take place at the offices of
Performance Engineering Corporation, 3949 Pender Drive, Fairfax, Virginia at
2:00 o'clock p.m. on the thirtieth (30th) day after the Corporation delivers
such notice to the Transferee, or at such other time and place as shall be fixed
by written agreement of the Corporation and the Transferee. At such Closing, the
Transferee shall deliver to the Corporation certificates representing the Stock
transferred to him by the Offending Stockholder, duly endorsed in blank for
transfer, or with duly executed blank Stock powers attached, free and clear of
all liens, claims or encumbrances, with evidence of payment for all transfer
taxes and fees, if any, and accompanied by such further instruments as may be
necessary or desirable, in the



                                       9
<PAGE>

opinion of counsel for the Corporation, to effect the transfer of such Stock.
The Corporation shall deliver to the Transferee or his personal representative
the payment (by certified or cashier's check) for the Stock, as provided in this
Section 3.7. Acceptance by any purchaser assignee, transferee, donee, pledgee or
other party of any of the Stock hold by any of the Stockholders shall evidence
conclusively the consent of such party to all the terms and provisions hereof,
and all such parties agree to do all things necessary and appropriate to
accomplish the purchase and sale pursuant to this Section 3.7.

         If the Transferee or his personal representative does not tender the
certificates for the shares of Stock to be purchased as provided herein at such
Closing, the Corporation shall cause the transfer books of the Corporation to
reflect that such shares of Stock have been canceled upon the tender by the
Corporation to the Transferee or his personal representative of a certified or
cashier's check for the full amount of the purchase price as provided in this
Section 3.7. After the transfer books have been so modified and after such
tender of payment has been made (whether or not accepted by the Transferee or
his personal representative), neither the Transferee nor his personal
representative shall be considered to own Stock in the Corporation and shall
have no rights as a Stockholder to the extent of the shares of Stock so canceled
under the terms of this Section 3.7.

         3.8      CORPORATE ACTION AND STOCKHOLDER GUARANTY. If the Corporation
is unable to make any purchase required of it under this Agreement, or to
fulfill any obligation incurred in connection therewith because of the
provisions of applicable statutes or of its Articles of Incorporation or Bylaws,
the Corporation agrees to take such action as may be necessary to permit it to
make such purchases and the Stockholders agree that they will also take such
action (other than making additional capital contributions to the Corporation or
guaranteeing debts of the Corporation) as may be necessary for the Corporation
to make such purchases when, as and if required.

         If the Corporation shall, nevertheless, be unable or refuses to
purchase all of a Stockholder's Stock, or Offending Stockholder's transferred
Stock, or be unable to make payment upon any note given to a Stockholder in the
purchase of his Stock, or to a Transferee for purchase of transferred Stock, the
obligation of the Corporation with respect to the shares of Stock which the
Corporation shall be unable or refuses to purchase shall be deemed assumed by
the remaining Stockholders. The obligation of the Corporation to purchase such
Stock under this Agreement shall be primary and the aforementioned obligation of
the remaining Stockholders shall be secondary and conditional. If the remaining
Stockholders are called upon to purchase such Stock hereunder, each remaining
Stockholder shall be obligated to purchase, on the same terms and conditions as
would be applicable to a purchase by the Corporation, such portion of the Stock
offered for sale in proportion to the ratio that the number of shares owned by
him (on the date on which the Corporation's obligation to purchase such Stock
arose) bears to the total number of shares of Stock owned by the Stockholders on
such date, excluding the Stock which the Corporation is obligated to purchase.

                      ARTICLE IV. MISCELLANEOUS PROVISIONS

         4.1      STOCK LEGEND. The provisions of the Agreement shall apply to
all Stock in the


                                       10
<PAGE>

Corporation now owned or hereafter acquired by the Stockholders, whether
acquired by option exercise or otherwise.

         Each certificate evidencing shares of Stock of the Corporation shall
bear the following legend on the face of such certificate:

                           The shares of Stock represented by this certificate
                           (and all transfers thereof) are subject to the terms
                           of a Stockholders' Agreement dated as of September
                           18, 1992, by and among the Corporation and its
                           stockholders, a copy of which is on file at the
                           principal offices of the Corporation and is available
                           for inspection during reasonable business hours. No
                           transfer of any share represented by this certificate
                           shall be valid unless made in accordance with such
                           Agreement.

         In the event such legend cannot practicably be placed on the face of
such certificate, either alone or in conjunction with other legends required by
law or by this Agreement to be placed on the face of such certificate, the
legend shall be set out in conspicuous type on the back of the certificate, and
notice thereof shall be given in conspicuous type on the front of the
certificate.

         4.2      AMENDMENT AND TERMINATION.  This Agreement may be altered,
amended or terminated at any time only by a written instrument executed by all
of the Stockholders of the Corporation. This Agreement shall terminate upon the
occurrence of any of the following events:

                  (i)  The bankruptcy, receivership or dissolution of the
Corporation; or

                  (ii) The death or disqualification of all Stockholders within
a period of sixty (60) days, in which case the Agreement shall be deemed to have
terminated immediately preceding the date on which the first such Stockholder
shall have died or become disqualified to practice his respective profession in
the Commonwealth of Virginia. Termination of this Agreement as herein provided
shall have no effect on any obligation of the parties which arose pursuant to
the purchase of Stock under this Agreement prior to its termination under this
Section 4.2.

         4.3      INSTRUCTIONS TO EXECUTOR. Each Stockholder shall execute a
will directing his respective executor to perform according to this Agreement
and to execute all documents necessary to effectuate the purposes of this
Agreement. The failure, however, of any Stockholder to execute such a will shall
not affect the rights of any Stockholder or the obligations of his estate, as
provided herein.

         4.4      NOTICES AND OTHER COMMUNICATION. Any notice, offer, acceptance
of an offer, or



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<PAGE>

other communication provided for or required by this Agreement shall be in
writing and shall be deemed to have been given when delivered by hand or when
deposited in the United States mail, certified or registered, return receipt
requested, postage prepaid, properly addressed to the party to whom such notice
or other communication is intended to be given. The proper address of the
Corporation shall be:

                       Performance Engineering Corporation
                       3949 Pender Drive
                       Fairfax, Virginia 22030

and in the case of any other party, shall be such address as such other party
may have previously furnished in writing to the Corporation or such other
party's last known address.

         4.5 ENFORCEABILITY. The parties hereto do hereby recognize and
acknowledge that it is impossible to measure in money the damages which would
result to a party or to the personal representative of a deceased party by
reason of a failure of any of the parties to perform any obligations imposed
upon him or it under this Agreement. Therefore, if any party or the personal
representative of any deceased party should institute an action or proceeding to
enforce the provisions hereof, any person against whom such action or proceeding
is brought hereby waives the claim or defense that such party or such personal
representative has an adequate remedy at law, and such person shall not urge in
any action or proceeding the claim or defense that such a remedy at law exists.

         4.6 POWER OF ATTORNEY. Each Stockholder hereby appoints the Corporation
as his agent and attorney-in-fact for the purpose of executing and delivering
any and all documents necessary to convey such Stockholder's Stock pursuant to
the provisions of this Agreement. In the event the Stockholder refuses to comply
with the provisions of this Agreement or is not present at the Closing, any
conveyance by such agent and attorney-in-fact shall be a conveyance of all of
the Stockholder's right, title and equity in and to the Stock. This power of
attorney is coupled with an interest and shall not expire upon the death or
incapacity of a Stockholder, nor may this power of attorney be terminated by any
Stockholder as long as this Agreement remains in effect.

         4.7 INVALID PROVISIONS. The invalidity or unenforceability of any one
or more of the particular provisions of this Agreement shall not affect the
enforceability of the other provisions hereof, all of which are inserted
conditionally on their being valid in law, and in the event one or more
provisions contained herein shall be invalid, this instrument shall be construed
as if such invalid provisions had not been inserted, and if such invalidity
shall be caused by the length of any period of time, the size of any area or the
scope of activities set forth in any provision hereof, such period of time, such
area or scope or all shall be considered to be reduced to a period, area or
scope which would cure such invalidity.

         4.8 BINDING EFFECT. This Agreement shall be binding upon and inure to
the benefit of the parties hereto and their respective heirs, executors,
administrators, legal representatives, successors and assigns.


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<PAGE>

         4.9      COUNTERPARTS. For the convenience of the parties hereto, any
number of counterparts hereof may be executed, and each such executed
counterpart shall be deemed to be an original instrument.

         4.10     ARBITRATION. Any controversy or claim arising out of or
relating directly or indirectly to the provisions of this Agreement shall be
settled by arbitration in accordance with the rules of the American Arbitration
Association, and judgment upon the award rendered by the Arbitrators may be
entered in any court having jurisdiction hereof.

         4.11     GOVERNING LAWS. This Agreement shall be interpreted, construed
and enforced in accordance with the laws of the Commonwealth of Virginia and
agree that any disputes arising out of this Agreement shall be litigated in
those courts.

         4.12     AUTHORITY. All provisions, terms and conditions of this
Agreement have been duly consented to, ratified, approved and adopted where
required by the Board of Directors of the Corporation, and appropriate authority
has been delegated to the officers of the Corporation to carry out this
Agreement.

         4.13     ARTICLE OR SECTION HEADINGS. The Articles and Section headings
contained in this Agreement are for convenience only and shall in no manner be
construed as part of this Agreement.

         4.14     GENDER. Where the context so requires, the masculine gender
shall be construed to include the feminine, a corporation, a trust or other
entity, and the singular shall be construed to include the plural and singular.

         4.15     ENTIRE AGREEMENT. This Agreement constitutes the sole and
entire agreement of the parties with respect to the matters contained herein,
and any representation, inducement, promise or agreement, whether oral or
written, which pertains to such matters and is not embodied herein shall be of
no force or effect.

         4.16     SECURITIES LAW RESTRICTIONS. As a condition of their
subscriptions and purchases and of the issuance of the Stock of the Corporation,
the parties hereby severally represent, warrant and covenant as follows:

                  (1)      That they understand that the Stock has not been
                           registered under the Securities Act of 1933, as
                           amended (the "Act"), in reliance upon exemptions
                           promulgated thereunder or interpretations thereof,
                           and cannot be offered for sale, sold or otherwise
                           transferred unless the Stock is subsequently so
                           registered or qualifies for exemption from
                           registration under the Act, that the certificates
                           representing the Stock shall bear a legend to such
                           effect, and that any transfer agent employed or
                           utilized by the Corporation shall be instructed not
                           to effect transfer of the Stock without prior written
                           authorization from the Corporation (or, if the
                           Corporation serves as its own transfer agent, a
                           notation shall be made in



                                       13
<PAGE>

                           the Corporation's records indicating the transfer
                           restriction to which the Stock is subject);

                  (2)      That the Stock is being acquired under this Agreement
                           by them in good faith solely for their own account,
                           for investment and not with a view toward resale or
                           other distribution within the meaning of the Act, and
                           that the Stock shall not be offered for sale, sold or
                           otherwise transferred without either registration or
                           exemption from registration under the Act;

                  (3)      That they have such knowledge and experience in
                           financial and business matters that they are capable
                           of evaluating the merits and risks of their
                           investment in the Stock, and that they understand and
                           are able to bear any economic risks associated with
                           such investment (including the necessity of holding
                           the shares for an indefinite period of time, inasmuch
                           as the Stock has not been registered under the Act);

                  (4)      That they are personally familiar with and have full
                           knowledge of the business which is intended to be
                           conducted by the Corporation, including financial
                           matters relating to such business, that they have
                           been given the opportunity to ask questions of, and
                           receive answers from, each other concerning the
                           intended business and financial affairs of the
                           Corporation, and the terms and conditions of their
                           purchase of the Stock and that they have been given
                           the further opportunity to obtain any additional
                           information necessary to verify the accuracy of the
                           foregoing information; and

                  (5)      That they understand that, notwithstanding any other
                           provisions of this Agreement regarding sale to third
                           parties, if an exemption for such sales is not
                           available, registration of the shares may be
                           required, but that the Corporation is under no
                           obligation either to register the shares or to
                           facilitate compliance or to comply with any
                           exemption.

         The certificates representing the Stock of the Corporation shall bear
the following legend:

                           The shares represented by this Certificate have not
                           been registered under the Securities Act of 1933 (the
                           "Act") and cannot be offered, sold or transferred in
                           absence of registration or the availability of an
                           exemption from registration under the Act and the
                           regulations promulgated thereunder.



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