Document:

Exhibit 10.3

          Baltimore, Maryland
                                                     $10,000,000.00
          March 23, 2000

                         REVOLVING LOAN PROMISSORY NOTE

          FOR VALUE  RECEIVED,  the  undersigned  GSE SYSTEMS,  INC., a Delaware
          corporation,  GSE PROCESS SOLUTIONS, INC., a Delaware corporation, and
          GSE  POWER  SYSTEMS,  INC.,  a  Delaware  corporation   (collectively,
          BORROWERS),  jointly and  severally,  promise to pay to the order of
          NATIONAL BANK OF CANADA, a Canadian chartered bank (LENDER),  at its
          New York branch, 125 West 55th Street, New York, New York 10019, or at
          such other places as the holder of this  Promissory Note may from time
          to  time   designate,   the  principal  sum  of  Ten  Million  Dollars
          ($10,000,000.00),  or so much as has been advanced to the BORROWERS as
          the proceeds of the LOAN,  as such term is defined and  described in
          the Loan And Security Agreement of even date herewith (as the same may
          be amended, modified,  extended,  renewed,  restated,  supplemented or
          replaced  from time to time  AGREEMENT  between  the LENDER and the
          BORROWERS, together with interest on the unpaid principal balance from
          time  to  time  outstanding  at the  rate or  rates  specified  in the
          AGREEMENT  until  paid in full and any and all other sums which may be
          owing to the holder of this Promissory Note by the BORROWERS  pursuant
          to this Promissory Note, on or before the TERMINATION  DATE, as such
          term is defined in the AGREEMENT,  or such earlier date as is required
          by the AGREEMENT.  This Promissory Note is the NOTE, as such term is
          defined in the  AGREEMENT.  The  following  terms  shall apply to this
          Promissory Note.

          1. Interest  Rates,  Calculation Of Interest,  And Terms Of Repayment.
          The BORROWERS, jointly and severally, promise to pay principal and all
          interest which accrues on the unpaid balance of this  Promissory  Note
          from  the  date  of  this  Promissory  Note  until  such  time  as the
          obligations  evidenced  hereunder have been paid in full, at the times
          and in accordance with the covenants,  procedures and requirements set
          forth in the AGREEMENT.  Interest shall accrue, be payable,  and shall
          be calculated as set forth in the AGREEMENT.  The  BORROWERS,  jointly
          and  severally,  further  promise to pay all  default  interest,  late
          payment   charges,   fees  and  other  expenses,   costs  and  payment
          obligations  as are required by the AGREEMENT to be made by any of the
          BORROWERS to or for the account of the LENDER.

          2.  Application  Of  Payments.  Except as  expressly  provided  to the
          contrary  in the  AGREEMENT,  all  payments  made  hereunder  shall be
          applied  first  to late  payment  charges  or other  sums  owed to the
          holder,  next to accrued interest,  and then to principal,  or in such
          other  order  or  proportion  as  the  holder,  in the  holders  sole
          discretion, may elect from time to time.

          3.  Prepayment.  The BORROWERS  rights to prepay this Promissory Note
          shall be governed by the terms and conditions of the AGREEMENT.

          4. Rights Upon Occurrence of an Event of Default.  Upon the occurrence
          of an EVENT OF  DEFAULT,  as such term is defined in the  AGREEMENT,
          the holder of this Promissory Note shall have the following  rights in
          addition to all other  rights and  remedies as are  authorized  by the
          AGREEMENT or otherwise available to the holder under applicable laws:

          4.1. Acceleration. The holder of this Promissory Note, in the holders
          sole  discretion  and without  notice or demand,  may  accelerate  and
          declare due and immediately  owing the entire unpaid principal balance
          plus  accrued  interest  and all other  sums  payable to the holder in
          accordance with the terms of any of the LOAN DOCUMENTS, as such term
          is defined in the AGREEMENT.

          4.2. Default Interest Rate. The holder of this Promissory Note, in the
          holders sole  discretion and without notice or demand,  may raise the
          rate of interest  accruing on the unpaid principal  balance by two (2)
          percentage  points  above the rate of interest  otherwise  applicable,
          independent  of whether  the holder  elects to  accelerate  the unpaid
          principal  balance as a result of such  default,  unless  prior to the
          imposition of the default rate of interest,  the  BORROWERS  cure such
          event to the satisfaction of the holder hereof.  Any individual waiver
          of the holders right to impose the default rate of interest shall not
          be  considered  a waiver of this  Section or any  future  right of the
          holder  to  impose  the  default  rate of  interest  pursuant  to this
          Section.

          4.3.  Confession  Of Judgment.  Each of the BORROWERS  authorizes  any
          attorney admitted to practice before any court of record in the United
          States  to  appear  on  its  behalf  in  any  court  in  one  or  more
          proceedings,  or before any clerk  thereof or  prothonotary,  or other
          court official, and to confess judgment against the BORROWERS in favor
          of the holder of this  Promissory  Note in the full amount due on this
          Promissory Note (including principal, accrued interest and any and all
          charges,  fees and  costs)  plus  attorneys  fees,  equal to  fifteen
          percent  (15%) of the amount then due,  plus court costs,  all without
          prior notice or opportunity  of the BORROWERS for prior hearing.  Each
          of the BORROWERS agrees and consents that venue and jurisdiction shall
          be proper in the Circuit  Court of any County of the State of Maryland
          or of Baltimore City, Maryland, or of the State of New York, or in the
          United  States  District  Court for the  District  of  Maryland or the
          United States  District  Court for the Southern  District of New York.
          Each of the  BORROWERS  waives the  benefit of any and every  statute,
          ordinance,  or rule of court which may be lawfully  waived  conferring
          upon it any right or privilege of exemption, homestead rights, stay of
          execution,  or  supplementary  proceedings,  or other  relief from the
          enforcement  or  immediate   enforcement  of  a  judgment  or  related
          proceedings on a judgment,  but without waiving any right the BORROWER
          may have to file a motion  to open,  modify or  vacate a  judgment  by
          confession in accordance  with Rule 2-611(c) of the Maryland  Rules or
          the equivalent  statute under New York law. The authority and power to
          appear for and enter  judgment  against  any or all of the  BORROWERS,
          jointly and severally, shall not be exhausted by one or more exercises
          thereof,  or by any  imperfect  exercise  thereof,  and  shall  not be
          extinguished by any judgment entered pursuant thereto;  such authority
          and power may be exercised on one or more occasions from time to time,
          in the same or different  jurisdictions,  as often as the holder shall
          deem necessary, convenient, or proper.

          5. Interest Rate After Judgment. If judgment is entered against any or
          all of the  BORROWERS  on this  Promissory  Note,  the  amount  of the
          judgment  entered (which may include  principal,  interest,  fees, and
          costs) shall bear interest at the higher of the maximum  interest rate
          imposed  upon  judgments  by  applicable  law or the  above  described
          default  interest  rate,  to be determined on the date of the entry of
          the judgment.

          6. Expenses Of Collection And Attorneys  Fees. Should this Promissory
          Note  be  referred  to an  attorney  for  collection,  whether  or not
          judgment  has been  confessed or suit has been filed,  the  BORROWERS,
          jointly and severally, shall pay all of the holders reasonable costs,
          fees and expenses,  including  reasonable  attorneys  fees, resulting
          from such referral.

          7. Waiver of  Defenses.  In the event any one or more  holders of this
          Promissory Note transfer this  Promissory Note for value,  each of the
          BORROWERS  agrees that all subsequent  holders of this Promissory Note
          who take for value and without actual  knowledge of a claim or defense
          of any of the BORROWERS against a prior holder shall not be subject to
          any claims or defenses  which any of the  BORROWERS may have against a
          prior holder, all of which are waived as to the subsequent holder, and
          that all such subsequent  holders shall have all rights of a holder in
          due course with respect to the  BORROWERS  even though the  subsequent
          holder may not qualify,  under applicable law, absent this section, as
          a holder in due  course.  The  BORROWERS  shall  retain all rights and
          claims which the BORROWERS may have against prior holders  despite any
          such transfers and the waiver of defenses  provided in this section as
          to subsequent holders.  Notwithstanding the foregoing,  nothing herein
          shall  represent  the waiver by any of the  BORROWERS  of any  defense
          based upon any payment  hereof made to any former  holder hereof prior
          to the  BORROWERS  having  been  notified  of  the  transfer  of  this
          Promissory Note to any subsequent holder.

          8. Waiver Of Protest.  Each of the BORROWERS,  and all parties to this
          Promissory  Note,  whether  maker,   indorser,  or  guarantor,   waive
          presentment, notice of dishonor and protest.

          9.  Extensions  Of  Maturity.  All  parties to this  Promissory  Note,
          whether maker, indorser, or guarantor, agree that the maturity of this
          Promissory Note, or any payment due hereunder,  may be extended at any
          time or from time to time without releasing, discharging, or affecting
          the liability of such party.

          10.  Manner and Method of  Payment.  All  payments  called for in this
          Promissory  Note shall be made in lawful money of the United States of
          America. If made by check,  draft, or other payment  instrument,  such
          check, draft, or other payment instrument shall represent  immediately
          available  funds.  In the holdes  discretion,  any payment made by a
          check,  draft, or other payment  instrument shall not be considered to
          have been made until such time as the funds  represented  thereby have
          been  collected  by the  holder.  Should  any  payment  date fall on a
          non-banking  day,  the  BORROWERS  shall make the  payment on the next
          succeeding banking day

          11.  Maximum Rate Of Interest.  Any provision  contained in any of the
          LOAN  DOCUMENTS  to the contrary  notwithstanding,  the holder of this
          Promissory Note shall not be entitled to receive or collect, nor shall
          the BORROWERS be obligated to pay, interest hereunder in excess of the
          maximum rate of interest permitted by the laws of any state determined
          to be  applicable  thereto or the laws of the United States of America
          applicable  to loans in such  applicable  state or states,  and if any
          provisions  of  this  Promissory  Note  or of any of  the  other  LOAN
          DOCUMENTS  shall ever be  construed  or held to permit or require  the
          charging, collection or payment of any amount of interest in excess of
          that permitted by such laws applicable thereto, the provisions of this
          paragraph   shall   control  and  shall   override   any  contrary  or
          inconsistent  provision.  The  intention  of the  parties is to at all
          times  conform  strictly  with all  applicable  usury laws,  and other
          applicable laws regulating the rates of interest which may be lawfully
          charged upon the credit facility  evidenced by this  Promissory  Note.
          The  interest  to be  paid  in  accordance  with  the  terms  of  this
          Promissory  Note  shall be held  subject  to  reduction  to the amount
          allowed under any usury or other laws as now or hereafter construed by
          the courts having  jurisdiction,  and any sums of money paid in excess
          of the  interest  rate allowed by law shall be applied in reduction of
          the principal amounts owing under this Promissory Note.

          12.  Notices.  Any notice or demand  required  or  permitted  by or in
          connection  with this  Promissory  Note  shall be given in the  manner
          specified  in the  AGREEMENT  for the  giving  of  notices  under  the
          AGREEMENT.  Notwithstanding  anything to the contrary, all notices and
          demands for payment  from the holder  actually  received in writing by
          the BORROWERS  shall be  considered  to be effective  upon the receipt
          thereof  by the  BORROWERS  regardless  of  the  procedure  or  method
          utilized to accomplish delivery thereof to the BORROWERS.

          13. Assignability.  This Promissory Note may be assigned by the LENDER
          or any  holder at any time or from time to time  without  notice to or
          consent from the BORROWERS.

          14. Binding Nature. This Promissory Note shall inure to the benefit of
          and be  enforceable  by the LENDER  and the  LENDERS  successors  and
          assigns  and any other  person to whom the  LENDER or any  holder  may
          grant an interest in the BORROWERS  obligations hereunder,  and shall
          be binding and enforceable against any or all of the BORROWERS and the
          BORROWERS respective successors and assigns.

          15.  Invalidity Of Any Part. If any provision or part of any provision
          of this Promissory Note shall for any reason be held invalid,  illegal
          or  unenforceable  in any  respect,  such  invalidity,  illegality  or
          unenforceability  shall  not  affect  any  other  provisions  of  this
          Promissory Note and this Promissory Note shall be construed as if such
          invalid,  illegal or unenforceable provision or part thereof had never
          been  contained  herein,  but only to the  extent  of its  invalidity,
          illegality, or unenforceability.

          16.  Choice  Of Law.  The laws of the  State  of New York  (excluding,
          however,  conflict of law  principles)  shall govern and be applied to
          determine all issues  relating to this  Promissory Note and the rights
          and  obligations  of  the  parties  hereto,  including  the  validity,
          construction,  interpretation,  and  enforceability of this Promissory
          Note and its various  provisions and the consequences and legal effect
          of all  transactions and events which resulted in the issuance of this
          Promissory  Note or which  occurred  or were to  occur as a direct  or
          indirect result of this Promissory Note having been executed.

          17.  Consent  To  Jurisdiction;  Agreement  As To  Venue.  Each of the
          BORROWERS  irrevocably  consents to the non-exclusive  jurisdiction of
          the courts of the State of New York and the State of  Maryland  and of
          the United  States  District  Courts for the Southern  District of New
          York and the District of Maryland, if a basis for federal jurisdiction
          exists. Each of the BORROWERS agrees that venue shall be proper in any
          circuit  court  of the  State of New  York or the  State  of  Maryland
          selected by the LENDER or in the United States  District Court for the
          Southern District of New York or the District of Maryland (as selected
          by the LENDER if a basis for federal  jurisdiction  exists and waives
          any right to object to the  maintenance  of a suit in any of the state
          or federal courts of the State of New York or the State of Maryland on
          the basis of improper venue or of inconvenience of forum.

          18. Unconditional Obligations.  The BORROWERS  obligations under this
          Promissory  Note  shall  be  the  joint  and  several,   absolute  and
          unconditional  duty and  obligation of each of the BORROWERS and shall
          be  independent of any rights of set-off,  recoupment or  counterclaim
          which any of the BORROWERS  might otherwise have against the holder of
          this Promissory Note. The BORROWERS,  jointly and severally, shall pay
          absolutely  the  payments of  principal,  interest,  fees and expenses
          required  hereunder,  free of any  deductions  and without  abatement,
          diminution or set-off.

          19. Seal and Effective  Date.  This  Promissory  Note is an instrument
          executed under seal and is to be considered  effective and enforceable
          as of the date set forth on the first page hereof,  independent of the
          date of actual execution and delivery

          20. Tense; Gender;  Defined Terms;  Section Headings.  As used herein,
          the singular includes the plural and the plural includes the singular.
          A reference  to any gender also applies to any other  gender.  Defined
          terms are entirely  capitalized  throughout.  The section headings are
          for convenience only and are not part of this Promissory Note.

          21. Actions Against Lender. Any action brought by any of the BORROWERS
          against the LENDER  which is based,  directly or  indirectly,  on this
          Promissory Note or any matter in or related to this  Promissory  Note,
          including but not limited to the making of the loan  evidenced  hereby
          or the administration or collection thereof,  shall be brought only in
          the courts of the State of New York or, if the  LENDER has  instituted
          action against any or all of the BORROWERS in such courts,  the courts
          of the State of  Maryland.  The  BORROWERS  agree that any forum other
          than the State of New York or the State of Maryland is an inconvenient
          forum and that a suit brought by the BORROWERS against the LENDER in a
          court of any  state  other  than the State of New York or the State of
          Maryland  should be  forthwith  dismissed  or  transferred  to a court
          located  in the State of New York or,  if the  LENDER  has  instituted
          action against the BORROWERS in such state, the State of Maryland,  by
          that Court.

          22. Waiver Of Jury Trial.  Each of the BORROWERS (by execution of this
          Promissory  Note) and the LENDER  (by  acceptance  of this  Promissory
          Note) agree that any suit,  action,  or  proceeding,  whether claim or
          counterclaim,  brought or  instituted  by or against any or all of the
          BORROWERS or the LENDER,  or any successor or assign any or all of the
          BORROWERS or the LENDER, on or with respect to this Promissory Note or
          any of the other LOAN DOCUMENTS, or which in any way relates, directly
          or indirectly, to the obligations of the BORROWERS to the LENDER under
          this  Promissory  Note  or any of the  other  LOAN  DOCUMENTS,  or the
          dealings of the parties with respect thereto, shall be tried only by a
          court and not by a jury. THE BORROWERS AND THE LENDER HEREBY EXPRESSLY
          WAIVE  ANY  RIGHT  TO A TRIAL  BY JURY IN ANY SUCH  SUIT,  ACTION,  OR
          PROCEEDING.
          IN WITNESS  WHEREOF,  each of the  BORROWERS  has duly  executed  this
          Promissory Note under seal as of the date first above written.

          WITNESS/ATTEST:                      GSE SYSTEMS, INC.

          _________________          By:      ____________________________(SEAL)
                                                 Jeffery G. Hough,
                                               Senior Vice President

                                              GSE PROCESS SOLUTIONS, INC.

         __________________          By:      ____________________________(SEAL)
                                                Jeffery G. Hough,
                                               Senior Vice President

                                                     GSE POWER SYSTEMS, INC.

          _________________          By:
                                              ____________________________(SEAL)
                                                    Jeffery G. Hough,
                                                 enior Vice President

                                 ACKNOWLEDGMENTS

          STATE OF MARYLAND, CITY/COUNTY OF BALTIMORE, TO WIT:

          I HEREBY  CERTIFY that on this ______ day of March,  2000,  before me,
          the  undersigned  Notary  Public of the State of Maryland,  personally
          appeared Jeffrey G. Hough,  and acknowledged  himself to be the Senior
          Vice President of GSE SYSTEMS, INC., a Delaware corporation,  and that
          he,  as  such,  being  authorized  so to do,  executed  the  foregoing
          instrument for the purposes  therein  contained by signing the name of
          GSE SYSTEMS, INC., by himself as Senior Vice President.

          IN WITNESS MY Hand and Notarial Seal.

                                               ___________________________(SEAL)
                                                  NOTARY PUBLIC
My Commission Expires:
______________________

STATE OFMARYLAND, CITY/COUNTY OF BALTIMORE, TO WIT:

          I HEREBY  CERTIFY that on this ______ day of March,  2000,  before me,
          the  undersigned  Notary  Public of the State of Maryland,  personally
          appeared Jeffery G. Hough,  and acknowledged  himself to be the Senior
          Vice President of GSE PROCESS SOLUTIONS, INC., a Delaware corporation,
          and  that  he,  as  such,  being  authorized  so to do,  executed  the
          foregoing instrument for the purposes therein contained by signing the
          name  of GSE  PROCESS  SOLUTIONS,  INC.  by  himself  as  Senior  Vice
          President.

         IN WITNESS MY Hand and Notarial Seal.

                                               ___________________________(SEAL)
                                                     NOTARY PUBLIC
My Commission Expires:
______________________

                                                   ACKNOWLEDGMENT

          STATE OF MARYLAND, CITY/COUNTY OF BALTIMORE, TO WIT:

          I HEREBY  CERTIFY that on this ______ day of March,  2000,  before me,
          the  undersigned  Notary  Public of the State of Maryland,  personally
          appeared Jeffrey G. Hough,  and acknowledged  himself to be the Senior
          Vice President of GSE POWER SYSTEMS, INC., a Delaware corporation, and
          that he, as such,  being  authorized so to do,  executed the foregoing
          instrument for the purposes  therein  contained by signing the name of
          GSE POWER SYSTEMS, INC., by himself as Senior Vice President.

          IN WITNESS MY Hand and Notarial Seal.

                                               ___________________________(SEAL)
                                                    NOTARY PUBLIC
My Commission Expires:
______________________Exhibit 10.4
          LIMITED GUARANTY AGREEMENT

          THIS LIMITED GUARANTY AGREEMENT  (GUARANTY) is given as of March 23,
          2000, by MANTECH INTERNATIONAL  CORPORATION,  a New Jersey corporation
          (GUARANTOR),  for the benefit of NATIONAL BANK OF CANADA, a Canadian
          chartered  bank  (LENDER),  with respect to the  obligations  of GSE
          SYSTEMS, INC., a Delaware corporation,  GSE PROCESS SOLUTIONS, INC., a
          Delaware  corporation,   and  GSE  POWER  SYSTEMS,  INC.,  a  Delaware
          corporation   (individually,   a  BORROWER  and  collectively,   the
          BORROWERS), to the LENDER.

                                 RECITALS

          The BORROWERS have requested  certain credit  accommodations  from the
          LENDER as set forth in the Loan and  Security  Agreement  of even date
          herewith by and between the  BORROWERS and the LENDER (as the same may
          be amended, modified,  extended,  renewed,  restated,  supplemented or
          replaced from time to time LOAN AGREEMENT). The LENDER has agreed to
          provide the requested credit accommodations to the BORROWERS, but only
          if, inter alia, the GUARANTOR provides to the LENDER the guaranties of
          payment and performance  set forth in this GUARANTY.  The GUARANTOR is
          willing to provide this  GUARANTY to the LENDER in order to induce the
          LENDER  to  provide  the  requested  credit   accommodations   to  the
          BORROWERS.

          All capitalized  terms used in this GUARANTY without  definition shall
          have the respective meanings given such terms in the LOAN AGREEMENT.

          NOW, THEREFORE,  in consideration of these premises and other good and
          valuable  consideration,  the  receipt  and  sufficiency  of which are
          hereby  acknowledged,  the  GUARANTOR  hereby agrees to provide to the
          LENDER the following guaranties and indemnifications.
          Section 1. Guaranty. The GUARANTOR guarantees:  (a) the payment of any
          and all sums now or  hereafter  due and  owing  to the  LENDER  by the
          BORROWERS (or any of them) arising out of, related to, as a result of,
          or in  connection  with the LOAN,  the  LETTERS OF CREDIT,  the CREDIT
          FACILITY, or any other existing or future indebtedness,  liability, or
          obligation  of every  kind,  nature,  type,  and  variety  owed by the
          BORROWERS  (or any of them) to the LENDER  from time to time,  arising
          out of,  related  to, as a result of, or in  connection  with the LOAN
          AGREEMENT,  or any  of  the  transactions  contemplated  by  the  LOAN
          DOCUMENTS (as defined  below),  including all renewals,  refinancings,
          extensions,  substitutions,  amendments, and modifications thereof, no
          matter when or how  created,  arising,  evidenced,  or  acquired,  and
          whether or not presently contemplated or anticipated, whether joint or
          several,  including,  but not limited  to, all  amounts of  principal,
          interest, charges,  reimbursements,  advancements,  escrows, and fees;
          (b) that all sums now or hereafter  due and owing by the BORROWERS (or
          any of them) to the LENDER arising out of, related to, as a result of,
          or in  connection  with the LOAN,  the  LETTERS OF CREDIT,  the CREDIT
          FACILITY, the LOAN AGREEMENT, or any of the transactions  contemplated
          by the LOAN  DOCUMENTS,  shall be paid  when  and as due,  whether  by
          reason of installment, maturity, acceleration or otherwise, time being
          of the essence; and (c) the timely, complete,  continuous,  and strict
          performance  and  observance  by the  BORROWERS  of each of the terms,
          covenants, agreements and conditions contained in any and all existing
          or future documents,  instruments,  agreements,  and writings of every
          kind, nature, type, and variety which evidence,  reflect, embody, give
          rise to or  secure  any  and all  existing  and  future  indebtedness,
          liabilities,  and  obligations of any kind of the BORROWERS (or any of
          them) to the LENDER  arising out of, related to, as a result of, or in
          connection with the LOAN, the LETTERS OF CREDIT,  the CREDIT FACILITY,
          the LOAN AGREEMENT,  or any of the transactions  contemplated  thereby
          (together with the LOAN AGREEMENT, collectively, LOAN DOCUMENTS). As
          used in this  GUARANTY,  the  term  OBLIGATIONS  shall  refer to the
          obligations of payment,  performance,  and  indemnification  which the
          GUARANTOR has undertaken and assumed  pursuant to this GUARANTY,  both
          as described in this Section and in other Sections of this GUARANTY

          Section 2. Maximum Amount of Guaranty.  The monetary  liability of the
          GUARANTOR with respect to the  OBLIGATIONS  hereunder shall be limited
          to  the  sum  of  One   Million   Eight   Hundred   Thousand   Dollars
          ($1,800,000.00)  (GUARANTY  MONETARY  AMOUNT);   provided  that  the
          proceeds of the  liquidation  of any of the  collateral  securing  the
          obligations  of the  BORROWERS  (or any of them) to the LENDER and any
          payments made by any of the BORROWERS or any other guarantor,  and any
          other  payments  obtained from any other source,  shall not be applied
          to,  or be  considered  a  discharge  of,  the  OBLIGATIONS  until all
          amounts,  other than those which have been guaranteed,  have been paid
          in full.  Notwithstanding  the  immediately  preceding  sentence,  the
          GUARANTY  MONETARY AMOUNT and the limitation set forth in this Section
          on  the  monetary  liability  of the  GUARANTOR  with  respect  to the
          OBLIGATIONS  shall not include nor be deemed a limit upon the LENDERS
          right  pursuant  to any other  Section  of this  GUARANTY  (including,
          without  limitation,  Section 19 hereof) to recover from the GUARANTOR
          costs and expenses, including reasonable attorneys fees, in enforcing
          or realizing upon this GUARANTY.  The GUARANTY  MONETARY AMOUNT may be
          reduced at each fiscal  year-end date  (beginning  with the BORROWERS
          fiscal year ending  December 31, 1999) upon the  determination  by the
          LENDER,  in each  instance,  that  the  BORROWERS  have  achieved  and
          satisfied the following conditions precedent:  (a) no EVENT OF DEFAULT
          (as  defined  below and as defined in the LOAN  AGREEMENT)  shall have
          occurred  hereunder or under the LOAN AGREEMENT during the fiscal year
          of the BORROWERS  ending on such fiscal  year-end date; (b) no DEFAULT
          (as  defined  in  the  LOAN  AGREEMENT)  shall  have  occurred  and be
          continuing on such fiscal year end date;  (c) no default  (defined for
          purposes  of this  clause  (c)  to mean  any  event,  occurrence  or
          omission  which,  with the giving of notice,  the passage of time,  or
          both,  would constitute an EVENT OF DEFAULT) under this GUARANTY shall
          have  occurred and be  continuing on such fiscal  year-end  date;  (d)
          EBITDA (as defined in the LOAN  AGREEMENT)  of the BORROWERS and their
          consolidated  subsidiaries for the fiscal year of the BORROWERS ending
          on such  fiscal  year-end  date,  and  reported  to the  LENDER by the
          BORROWERS in their audited annual financial statements for such fiscal
          year,  shall  have been equal to at least Five  Million  Five  Hundred
          Thousand  Dollars  ($5,500,000.00);  and (e) NET PROFIT  AFTER TAX (as
          defined in the LOAN AGREEMENT) of the BORROWERS and their consolidated
          subsidiaries  for the  fiscal  year of the  BORROWERS  ending  on such
          fiscal  year-end  date, and reported to the LENDER by the BORROWERS in
          their audited annual financial  statements for such fiscal year, shall
          have been equal to at least One Million Three Hundred Thousand Dollars
          ($1,300,000.00).  On the first fiscal year-end date as of which all of
          the foregoing  conditions  precedent are achieved and  satisfied,  the
          GUARANTY  MONETARY  AMOUNT  under this GUARANTY  shall be the sum of
          Nine Hundred  Thousand  Dollars  ($900,000.00).  On the second  fiscal
          year-end  date as of which all of the foregoing  conditions  precedent
          are achieved and satisfied,  this GUARANTY shall be released.  As used
          in this Section 2, the term fiscal year shall mean the FISCAL YEAR
          of the BORROWERS as defined in the LOAN AGREEMENT.

          Section 3. Letter of Credit.  (a) The  GUARANTOR has agreed to deliver
          to the  LENDER an  irrevocable  standby  letter  of  credit  having an
          original   undrawn  face  amount  of  Nine  Hundred  Thousand  Dollars
          ($900,000.00) naming the LENDER as beneficiary, issued by Mellon Bank,
          First Union National Bank or another bank acceptable to the LENDER, on
          terms and provisions acceptable to the LENDER and having an expiration
          date not less  than one (1) year from the date of  issuance  (ManTech
          L/C).  The ManTech L/C will serve as part of the  BORROWING  BASE for
          the LOAN to the BORROWERS.

          (b)  Effective  upon the due  delivery  to the LENDER of the  original
          fully executed, issued and effective ManTech L/C satisfying all of the
          conditions  set forth  above,  and so long as the ManTech L/C shall be
          effective,  the  provisions  of  Section 2 of this  GUARANTY  shall be
          deemed  amended to the effect that the  GUARANTY  MONETARY  AMOUNT set
          forth in Section 2 shall be reduced by an amount equal to the original
          undrawn face amount of the ManTech L/C. Upon expiration of the ManTech
          L/C, the amendments to the GUARANTY  MONETARY AMOUNT set forth in this
          clause (b) shall immediately and without further notice be void and of
          no further  force and effect and the  provisions of Section 2 shall be
          as stated in Section 2.

          Section 4. Nature Of Guaranty.  This GUARANTY: (a) is (i) irrevocable,
          (ii) absolute and unconditional, (iii) direct, immediate, and primary,
          and (iv) one of  payment  and not just  collection;  and (b) makes the
          GUARANTOR a surety to the LENDER with respect to the  OBLIGATIONS  and
          the equivalent of a co-obligor  with the BORROWERS.  Without  limiting
          the foregoing,  it is specifically  understood that any  modification,
          limitation or discharge of any of the  liabilities  or  obligations of
          the  BORROWERS  (or any of  them),  any other  guarantor  or any other
          obligor under any of the LOAN DOCUMENTS,  arising out of, or by virtue
          of, any bankruptcy, arrangement,  reorganization or similar proceeding
          for  relief of debtors  under  federal  or state law  initiated  by or
          against the  BORROWERS  (or any of them),  any other  guarantor or any
          obligor  under  any of the LOAN  DOCUMENTS  shall not  modify,  limit,
          lessen, reduce, impair,  discharge,  or otherwise affect the liability
          of the GUARANTOR hereunder in any manner whatsoever, and this GUARANTY
          shall remain and continue in full force and effect.

          Section 5. Accuracy Of Representations.  The GUARANTOR guaranties that
          all representations and warranties made by the GUARANTOR to the LENDER
          prior to or after the date of this  GUARANTY are and will  continue to
          be true, correct, accurate, and complete and not knowingly misleading,
          and,  subject to the  limitations  set forth in Section 2 hereof,  the
          GUARANTOR  agrees to indemnify  and hold the LENDER  harmless from any
          loss,  cost, or expense which the LENDER may suffer,  sustain or incur
          as a result of any  representation  or statement of the  BORROWERS (or
          any of them) or of the GUARANTOR being  materially  false,  incorrect,
          inaccurate, incomplete, or knowingly misleading.

          Section 6. Representations And Warranties Of Guarantor.  To induce the
          LENDER to accept this GUARANTY for the purposes for which it is given,
          the GUARANTOR represents and warrants to the LENDER as follows:

          (a) The GUARANTOR is a corporation  duly organized,  validly  existing
          and in good standing under the laws of the state of its incorporation.
          The GUARANTOR has the lawful power to own its properties and to engage
          in the  businesses  it  conducts,  and is duly  qualified  and in good
          standing as a foreign  corporation  in the  jurisdictions  wherein the
          nature of the business  transacted by it or property owned by it makes
          such qualification  necessary and the failure to so qualify would have
          a material  adverse  effect on the ability of the GUARANTOR to perform
          its OBLIGATIONS hereunder.

          (b) Any financial statements submitted by the GUARANTOR to the LENDER,
          including  any  schedules  and  notes  pertaining  thereto,  have been
          prepared in accordance with G.A.A.P. (as defined below), and fully and
          fairly  present the financial  condition of the GUARANTOR at the dates
          thereof and the results of operations for the periods covered thereby,
          and  there  has  been no  material  adverse  change  in the  financial
          condition or businesses of the GUARANTOR from the dates thereof to the
          date hereof,  other than as disclosed to the LENDER.  All  information
          submitted by or on behalf of the GUARANTOR in  connection  with any of
          the  OBLIGATIONS  is  true,  accurate  and  complete  in all  material
          respects  as of  the  date  made  and  contains  no  knowingly  false,
          incomplete or misleading statements.

          (c)  There  are  no  material  actions,  suits,   investigations,   or
          proceedings pending, or to the knowledge of the GUARANTOR,  threatened
          against  the  GUARANTOR  or the  assets  of the  GUARANTOR,  except as
          specifically disclosed on Schedule 5(c) attached hereto. The GUARANTOR
          has no material direct or contingent  liability known to the GUARANTOR
          and not  previously  disclosed to the LENDER,  nor does the  GUARANTOR
          know of or have any reason to expect any  material  adverse  change in
          the  GUARANTORS  assets,   liabilities,   properties,   business,  or
          condition, financial or otherwise.

          (d)  The  GUARANTOR  is  not in  default  with  respect  to any of its
          existing indebtedness, and the making and performance of this GUARANTY
          will  not  (immediately,  with the  passage  of time,  the  giving  of
          notices,  or  both),  (i)  violate  the  charter  or  by-laws  of  the
          GUARANTOR,  (ii) violate any laws, (iii) result in a default under any
          material contract,  agreement, or instrument to which the GUARANTOR is
          a party or by which the  GUARANTOR or its  property is bound,  or (iv)
          result in the creation or imposition  of any security  interest in, or
          lien or  encumbrance  upon,  any of the  assets of the  GUARANTOR.  No
          approval,  consent,  order,  authorization  or  license  by, or giving
          notice  to,  or  taking  any  other   action  with   respect  to,  any
          governmental  or  regulatory  authority  or agency is required for the
          execution  and delivery by the  GUARANTOR of this  GUARANTY or for the
          performance by the GUARANTOR of any of the agreements and  obligations
          hereunder.

          (e) The GUARANTOR has the power and legal  authority to enter into and
          perform  this  GUARANTY,  to incur the  OBLIGATIONS,  and to  perform,
          observe  and  comply  with  all  of  the  GUARANTORS  agreements  and
          obligations  hereunder.  The GUARANTOR has taken all corporate  action
          necessary to authorize the  execution,  delivery,  and  performance of
          this GUARANTY.

          (f)  This  GUARANTY,  when  delivered,  will be  valid,  binding,  and
          enforceable in accordance with its terms.

          (g) The incurring or  satisfaction of the OBLIGATIONS has not left and
          will not leave the GUARANTOR  insolvent,  with an  unreasonably  small
          capital, or unable to pay existing or future debts as they mature

          Section 7.  Reporting  Requirements.  The  GUARANTOR  shall submit the
          following items to the LENDER:

          (a) As soon as  available  and in any  event  within  forty-five  (45)
          calendar days after the end of each of the first three fiscal quarters
          of each fiscal year of the  GUARANTOR,  the GUARANTOR  shall submit to
          the  LENDER  a  statement  of  income  and  retained  earnings  of the
          GUARANTOR for the period  commencing at the end of the previous fiscal
          year and ending with the end of such  quarter and a statement  of cash
          flow for the  GUARANTOR  for the portion of the fiscal year ended with
          the last day of such quarter,  and a balance sheet of the GUARANTOR as
          of the  end of such  fiscal  quarter,  all in  reasonable  detail  and
          stating  in   comparative   form  the   respective   figures  for  the
          corresponding  date and  period in the  previous  fiscal  year and all
          prepared in accordance  with G.A.A.P.,  and certified by an officer of
          the GUARANTOR familiar with the financial  operations of the GUARANTOR
          (subject to year-end adjustments).

          (b) As soon as available  and in any event  within one hundred  twenty
          (120)  calendar  days  after  the  end  of  each  fiscal  year  of the
          GUARANTOR, the GUARANTOR shall submit to the LENDER annual audited and
          unqualified   consolidated   financial  statements,   which  shall  be
          accompanied  by  management  letters (if issued)  and  certified  by a
          nationally recognized independent certified public accountant.

          (c) All financial statements shall be in reasonable detail,  including
          all supporting  schedules and comments  necessary to verify or confirm
          entries in the financial statements. All financial statements shall be
          prepared in accordance  with G.A.A.P.  As used in this  GUARANTY,  the
          term  G.A.A.P.  means,  with  respect to any date of  determination,
          generally  accepted  accounting  principles  as used by the  Financial
          Accounting   Standards   Board  and/or  the   American   Institute  of
          Certificate Public  Accountants,  consistently  applied and maintained
          throughout the periods indicated. The costs of supplying the financial
          statements shall be paid by the GUARANTOR.

          Section 8. Lender Need Not Pursue  Other  Rights.  The LENDER shall be
          under no obligation to pursue any of the LENDERS  rights and remedies
          against any BORROWER or any of the collateral of any BORROWER securing
          the  obligations  of the  BORROWERS  (or any of them) to the LENDER or
          against any other  guarantor or any collateral of any other  guarantor
          before  pursuing  the  LENDERS   rights  and  remedies   against  the
          GUARANTOR.

          Section 9. Certain Rights Of Lender.  The GUARANTOR  hereby assents to
          any and all terms and agreements  between the LENDER and the BORROWERS
          (or any of them) or between  the LENDER and any other  guarantor,  and
          all amendments and modifications  thereof,  whether presently existing
          or  hereafter  made and whether  oral or in  writing.  The LENDER may,
          without compromising,  impairing, diminishing, or in any way releasing
          the GUARANTOR from the OBLIGATIONS and without  notifying or obtaining
          the prior approval of the GUARANTOR, at any time or from time to time:
          (a) waive or excuse a default by the BORROWERS (or any of them) or any
          other guarantor,  or delay in the exercise by the LENDER of any or all
          of the  LENDERS  rights or remedies  with  respect to such default or
          defaults;  (b) grant  extensions of time for payment or performance by
          the  BORROWERS  or  any  other  guarantor;  (c)  release,  substitute,
          exchange, surrender, or add collateral of any BORROWER or of any other
          guarantor, or waive, release, or subordinate, in whole or in part, any
          lien or security  interest  held by the LENDER on any real or personal
          property securing payment or performance,  in whole or in part, of the
          obligations  of the BORROWERS (or any of them) to the LENDER or of any
          other  guarantor;  (d) release the  BORROWERS  (or any of them) or any
          other  guarantor;  (e) apply  payments made by the BORROWERS or by any
          other  guarantor to any sums owed by the  BORROWERS to the LENDER,  in
          any order or manner,  or to any specific  account or accounts,  as the
          LENDER may elect; and (f) modify,  change,  renew, extend, or amend in
          any respect the LENDERS agreement with the BORROWERS (or any of them)
          or any  other  guarantor,  or any  document,  instrument,  or  writing
          embodying  or  reflecting  the  same,   including  without  limitation
          modifications  which  increase  the amount of the  obligations  of the
          BORROWERS  under the LOAN  DOCUMENTS  or extend  the  maturity  of the
          obligations of the BORROWERS under the LOAN DOCUMENTS.

          Section 10. Waivers By Guarantor.  The GUARANTOR  waives:  (a) any and
          all notices  whatsoever  with respect to this GUARANTY or with respect
          to any of the  obligations  of the  BORROWERS  (or any of them) to the
          LENDER,  including,  but not  limited to,  notice of (i) the  LENDERS
          acceptance  hereof or the  LENDERS  intention to act, or the LENDERS
          action,  in  reliance  hereon,  (ii) the present  existence  or future
          incurring of any of the  obligations of the BORROWERS (or any of them)
          to the LENDER or any terms or amounts  thereof or any change  therein,
          (iii) any  default by the  BORROWERS  (or any of them) or any  surety,
          pledgor,  grantor  of  security,  guarantor  or  any  person  who  has
          guarantied  or  secured  in whole or in part  the  obligations  of the
          BORROWERS  (or any of them) to the LENDER,  and (iv) the  obtaining or
          release of any guaranty or surety agreement,  pledge,  assignment,  or
          other security for any of the  obligations of the BORROWERS (or any of
          them) to the LENDER; (b) presentment and demand for payment of any sum
          due from the  BORROWERS  (or any of them) or any other  guarantor  and
          protest of nonpayment; (c) demand for performance by the BORROWERS (or
          any of  them) or any  other  guarantor;  and (d) any and all  defenses
          based on suretyship or impairment of collateral.

          Section  11.  Unenforceability  Of  Obligations  Of  Borrowers.   This
          GUARANTY  shall  be  valid,  binding,  and  enforceable  even  if  the
          obligations of the BORROWERS to the LENDER which are guarantied hereby
          are now or hereafter become invalid or unenforceable for any reason.

          Section 12. No Conditions Precedent.  This GUARANTY shall be effective
          and  enforceable   immediately  upon  its  execution.   The  GUARANTOR
          acknowledges   that  no  unsatisfied   conditions   precedent  to  the
          effectiveness and enforceability of this GUARANTY exist as of the date
          of its execution and that the effectiveness and enforceability of this
          GUARANTY is not in any way  conditioned or contingent  upon any event,
          occurrence,  or happening,  or upon any  condition  existing or coming
          into existence either before or after the execution of this GUARANTY.

          Section 13. No Duty To  Disclose.  The LENDER shall have no present or
          future duty or  obligation to discover or to disclose to the GUARANTOR
          any information,  financial or otherwise, concerning any BORROWER, any
          other guarantor,  or any collateral securing either the obligations of
          any  BORROWER  to the  LENDER  or of any  other  person  who may  have
          guarantied in whole or in part the obligations of the BORROWERS to the
          LENDER.  The  GUARANTOR  waives  any right to claim or assert any such
          duty or obligation on the part of the LENDER.  The GUARANTOR agrees to
          obtain    all    information    which    the    GUARANTOR    considers
          either appropriate  or relevant to this  GUARANTY  from sources  other
          than the  LENDER and to become  and  remain at all times  current  and
          continuously  apprised of all  information  concerning  the BORROWERS,
          other guarantors, and any collateral which is material and relevant to
          the obligations of the GUARANTOR under this GUARANTY.
          Section  14.  Existing Or Future  Guaranties.  The  execution  of this
          GUARANTY  shall  not  discharge,  terminate  or in any way  impair  or
          adversely affect the validity or  enforceability of any other guaranty
          given by the  GUARANTOR to the LENDER.  The  execution and delivery by
          the  GUARANTOR  of any future  guaranty  for the benefit of the LENDER
          shall not  discharge,  terminate,  or in any way  impair or  adversely
          affect the validity or enforceability of this GUARANTY. All guaranties
          provided by the  GUARANTOR to the LENDER are intended to be cumulative
          and shall remain in full force and effect unless and until  discharged
          and  terminated in accordance  with any expressly  stated  termination
          provisions set forth therein.

          Section 15. Cumulative Liability. The liability of the GUARANTOR under
          this  GUARANTY  shall  be  cumulative  to,  and  not in lieu  of,  the
          GUARANTORS liability under any other LOAN DOCUMENT or in any capacity
          other than as GUARANTOR hereunder

          Section 16. Obligations Are Unconditional. The payment and performance
          of the OBLIGATIONS  shall be the absolute and  unconditional  duty and
          obligation of the  GUARANTOR,  and shall be independent of any defense
          or  any  rights  of  setoff,  recoupment  or  counterclaim  which  the
          GUARANTOR might  otherwise have against the LENDER,  and the GUARANTOR
          shall pay and perform these  OBLIGATIONS,  free of any  deductions and
          without  abatement,  diminution  or  setoff.  Until  such  time as the
          OBLIGATIONS  have been fully paid and performed,  the  GUARANTOR:  (a)
          shall not suspend or discontinue any payments provided for herein; (b)
          shall  perform  and  observe  all  of  the  covenants  and  agreements
          contained in this GUARANTY;  and (c) shall not terminate or attempt to
          terminate  this  GUARANTY  for any  reason.  No delay by the LENDER in
          making  demand on the GUARANTOR for  satisfaction  of the  OBLIGATIONS
          shall  prejudice or in any way impair the LENDERS  ability to enforce
          this GUARANTY.

          Section 17. Defenses Against Borrowers. The GUARANTOR waives any right
          to assert against the LENDER any defense (whether legal or equitable),
          claim,  counterclaim,  or right of  setoff  or  recoupment  which  the
          GUARANTOR  may now or hereafter  have against the BORROWERS (or any of
          them) or any other guarantor.
          Section 18. Events  Authorizing  Acceleration Of The Obligations.  The
          occurrence of any of the following  (each an EVENT OF DEFAULT) shall
          entitle the LENDER,  without notice or demand,  to accelerate and call
          due the OBLIGATIONS, even if the LENDER has not accelerated and called
          due the sums owed to the LENDER by the BORROWERS: (a) the commencement
          by any of the  BORROWERS  or the  GUARANTOR  of a  voluntary  case  or
          proceeding  under  any  federal  or state  bankruptcy,  insolvency  or
          similar law; (b) the commencement of an involuntary case or proceeding
          against any of the  BORROWERS  or the  GUARANTOR  under any federal or
          state bankruptcy, insolvency, or similar law, and either (i) such case
          or proceeding is not dismissed  within ninety (90) calendar days after
          commencement, or (ii) an order for relief is entered in such case; (c)
          the appointment of a receiver, assignee, custodian, trustee or similar
          official  under any federal or state  insolvency or creditors  rights
          law  for  any  property  of any  BORROWER  or the  GUARANTOR;  (d) the
          GUARANTOR  shall  suffer  final  judgments  for the  payment  of money
          aggregating in excess of Two Hundred Fifty Thousand Dollars ($250,000)
          and shall not  discharge  the same within a period of thirty (30) days
          unless, pending further proceedings,  execution has not been commenced
          or if commenced has been effectively stayed; (e) the occurrence of any
          EVENT OF DEFAULT as such term is defined in the LOAN AGREEMENT;  (f)
          a failure  of the  GUARANTOR  to perform  any  covenant  or  agreement
          contained  in this  GUARANTY  or in any other  agreement  between  the
          GUARANTOR and the LENDER;  (g) any  representation or warranty made in
          this  GUARANTY or in any report or  financial  statement  furnished in
          connection  with this  GUARANTY,  shall  prove to have  been  false or
          misleading  when made;  (h) the  LENDER in the good  faith  reasonable
          exercise of the LENDERS discretion determines that a material adverse
          change has occurred in the financial  condition of the GUARANTOR;  (i)
          the  liquidation  or  dissolution  of any of the  BORROWERS  or of the
          GUARANTOR;  or (j) a failure of the  GUARANTOR  to satisfy  any of the
          obligations of the GUARANTOR to the LENDER with respect to any loan or
          extension of credit by the LENDER to the  GUARANTOR or under any other
          guaranty given by the GUARANTOR to the LENDER.

          Section 19.  Expenses Of Collection And Attorneys  Fees.  Should this
          GUARANTY  be referred to an attorney  for  collection,  the  GUARANTOR
          shall pay all of the  holders  reasonable  costs,  fees and  expenses
          resulting from such referral,  including reasonable  attorneys  fees,
          which the holder may incur, even though suit has not been filed.

          Section  20.  Interest  Rate After  Judgment.  If judgment is e ntered
          against the  GUARANTOR  on this  GUARANTY,  the amount of the judgment
          entered (which,  unless  applicable law  specifically  provides to the
          contrary,  and  subject  to the  limitations  set  forth in  Section 2
          hereof,  includes all principal,  prejudgment interest,  late charges,
          prepayment  charges  if any are  provided  for,  collection  expenses,
          attorneys  fees,  and court costs) shall bear interest at the highest
          rate after default  authorized by the LOAN DOCUMENTS as of the date of
          entry of the judgment to the extent  permitted by  applicable  law. In
          the event any statute or rule of court  specifies the rate of interest
          which a judgment on this GUARANTY may bear or the amount on which such
          interest  rate may  apply  and such  rate or  amount is less than that
          called  for in the  preceding  sentence  absent  a  restriction  under
          applicable law, the GUARANTOR agrees to pay to the order of the LENDER
          an amount as will equal the  interest  computed  at the  highest  rate
          after default provided for in the LOAN DOCUMENTS which would be due on
          the  judgment  amount  (which,  for this  purpose,  but subject to the
          limitations  set forth in  Section 2 hereof,  shall be  considered  to
          include all principal,  prejudgment interest, late charges, prepayment
          charges if any are provided for,  collection expense fees,  attorneys
          fees,  and court  costs)  less the  interest  due on the amount of the
          judgment which bears judgment interest.

          Section  21.  Enforcement  During  Bankruptcy.   Enforcement  of  this
          GUARANTY  shall not be stayed or in any way delayed as a result of the
          filing of a  petition  under the United  States  Bankruptcy  Code,  as
          amended, by or against any or all of the BORROWERS.  Should the LENDER
          be required to obtain an order of the United States  Bankruptcy  Court
          to begin  enforcement  of this GUARANTY after the filing of a petition
          under the United States Bankruptcy Code, as amended, by or against any
          or all of the BORROWERS,  the GUARANTOR hereby consents to this relief
          and agrees to file or cause to be filed all  appropriate  pleadings to
          evidence  and  effectuate  such  consent  and to enable  the LENDER to
          obtain the relief requested.

          Section  22.  Remedies  Cumulative.  All of the  LENDERS  rights  and
          remedies shall be cumulative and any failure of the LENDER to exercise
          any right hereunder shall not be construed as a waiver of the right to
          exercise  the same or any other  right at any  time,  and from time to
          time, thereafter.

          Section  23.  Continuing  Guaranty.  This  GUARANTY  is  a  continuing
          guaranty of all existing and future  obligations  of the BORROWERS (or
          any of them) to the LENDER arising out of, related to, as a result of,
          or in  connection  with the LOAN,  the  LETTERS OF CREDIT,  the CREDIT
          FACILITY, the LOAN AGREEMENT, or any of the transactions  contemplated
          by the LOAN  DOCUMENTS.  Except as provided in Section 2 hereof,  this
          GUARANTY  may not be  terminated  by the  GUARANTOR  until  after  the
          termination of the LOAN  DOCUMENTS,  in accordance with the provisions
          thereof,  and the  payment  (which  payment  shall not be  subject  to
          challenge or contest) in full of all of the OBLIGATIONS and all of the
          BORROWERS  obligations  and  liabilities to the LENDER under the LOAN
          DOCUMENTS.

          Section  24.  Reinstatement.  If at any time any  payment,  or portion
          thereof, made by, or for the account of, any BORROWER or the GUARANTOR
          on account of any of the obligations and liabilities  under any of the
          LOAN   DOCUMENTS  is  set  aside  by  any  court  or  trustee   having
          jurisdiction  as a voidable  preference,  or fraudulent  conveyance or
          must  otherwise be restored or returned by the LENDER to a BORROWER or
          any other person or entity under any  insolvency,  bankruptcy or other
          federal  and/or  state  laws  or  as  a  result  of  any  dissolution,
          liquidation or  reorganization  of any BORROWER or any other person or
          entity, or for any other reason, the GUARANTOR hereby agrees that this
          GUARANTY  shall  continue  and  remain in full  force and effect or be
          reinstated,  as the case may be, all as though such payment(s) had not
          been made.

          Section 25.  Rights Of  Subrogation,  Etc. In the event the  GUARANTOR
          pays any sum to or for the  benefit  of the  LENDER  pursuant  to this
          GUARANTY,  the  GUARANTOR  may not enforce any right of  contribution,
          indemnification,  exoneration,  reimbursement,  subrogation  or  other
          right or remedy  against any  BORROWER,  any other  guarantor,  or any
          collateral, whether real, personal, or mixed, securing the obligations
          of  any  BORROWER  to  the  LENDER  or the  obligations  of any  other
          guarantor to the LENDER until such time as the LENDER has been paid in
          full and has no further claim against any of the BORROWERS,  any other
          guarantor,  or any collateral.  The GUARANTOR  waives and releases any
          claim which the  GUARANTOR  hereafter  may have  against the LENDER if
          some action of the LENDER, whether intentional or negligent,  impairs,
          destroys,  or in any way adversely  affects any right of contribution,
          indemnification,  exoneration, reimbursement, subrogation, or the like
          which the GUARANTOR may have upon the payment of any sum to or for the
          benefit of the LENDER pursuant to this GUARANTY.

          Section 26.  Subordination Of Certain  Indebtedness.  If the GUARANTOR
          advances any sums to any BORROWER or its successors or assigns,  or if
          any  BORROWER or its  successors  or assigns  shall  hereafter  become
          indebted  to the  GUARANTOR,  such  sums  and  indebtedness  shall  be
          subordinate  in all respects to the amounts then or thereafter due and
          owing to the LENDER by such BORROWER.

          Section 27.  Renewals,  Etc. This GUARANTY shall apply to all sums now
          or  hereafter  owed by any of the  BORROWERS  to the LENDER and to all
          extensions,  modifications,  amendments, renewals,  substitutions, and
          refinancings thereof.

          Section  28.  Choice  Of  Law.  The  laws  of the  State  of New  York
          (excluding,  however,  conflict of law principles) shall govern and be
          applied to  determine  all issues  relating to this  GUARANTY  and the
          rights and obligations of the parties hereto,  including the validity,
          construction,  interpretation, and enforceability of this GUARANTY and
          its various  provisions and the  consequences  and legal effect of all
          transactions  and  events  which  resulted  in the  issuance  of  this
          GUARANTY  or which  occurred  or were to occur as a direct or indirect
          result of this GUARANTY having been executed.

          Section  29.  Consent  To  Jurisdiction;  Agreement  As To Venue.  The
          GUARANTOR  irrevocably  consents to the non-exclusive  jurisdiction of
          the courts of the State of  Maryland  and the State of New York and of
          the United States  District Court for the District of Maryland and for
          the Southern District of New York, if a basis for federal jurisdiction
          exists. The GUARANTOR agrees that venue shall be proper in any circuit
          court of the State of  Maryland  or the State of New York  selected by
          the LENDER or in the United States  District Court for the District of
          Maryland  or for the  Southern  District  of New  York if a basis  for
          federal  jurisdiction  exists  and  waives  any right to object to the
          maintenance  of a suit in any of the  state or  federal  courts of the
          State of  Maryland  or the State of New York on the basis of  improper
          venue or of inconvenience of forum.

          Section  30.  Proofs  Of  Sums  Due  On  Guaranty.  In any  action  or
          proceeding  brought  by the  LENDER to  collect  the sums owed on this
          GUARANTY,  a  certificate  signed by an officer of the LENDER  setting
          forth the unpaid  balances of  principal,  and any  accrued  interest,
          default interest,  attorneys fees, and late charges owed with respect
          hereto shall be presumed  correct and shall be  admissible in evidence
          for the purpose of establishing  the truth of what it asserts.  If the
          GUARANTOR  wishes to contest  the  accuracy of the figure set forth in
          any such  certificate,  the GUARANTOR shall have the burden of proving
          that the certificate is inaccurate or incorrect.

          Section 31.   Actions  Against  Lender.  Any  action  brought  by  the
          GUARANTOR  against the LENDER which is based,  directly or indirectly,
          on this  GUARANTY  or any  matter  in or  related  to  this  GUARANTY,
          including but not limited to the  obligations  of the BORROWERS to the
          LENDER, the administration,  collection, or enforcement thereof, shall
          be  brought  only in the courts of the State of New York or, if LENDER
          has instituted  action against the GUARANTOR in such court,  the State
          of Maryland.  The GUARANTOR agrees that any forum other than the State
          of Maryland or the State of New York is an inconvenient forum and that
          a suit brought by the  GUARANTOR  against the LENDER in a court of any
          state other than the State of New York or the State of Maryland should
          be forthwith  dismissed or transferred to a court located in the State
          of New York or,  if the  LENDER  has  instituted  action  against  the
          GUARANTOR in such state, the State of Maryland, by that court.

          Section 32.  Invalidity  Of Any Part.  If any provision or part of any
          provision  of this  GUARANTY  shall for any  reason  be held  invalid,
          illegal, or unenforceable in any respect, such invalidity, illegality,
          or  unenforceability  shall not  affect  any other  provisions  or the
          remaining part of any effective provisions of this GUARANTY,  and this
          GUARANTY  shall  be  construed  as  if  such  invalid,   illegal,   or
          unenforceable  provision  or part  thereof  had never  been  contained
          herein,  but only to the  extent  of its  invalidity,  illegality,  or
          unenforceability.

          Section 33. Amendment Or Waiver.  This GUARANTY may be amended only by
          a writing duly executed by the GUARANTOR and the LENDER.  No waiver by
          the LENDER of any of the  provisions  of this  GUARANTY  or any of the
          rights  or  remedies  of the  LENDER  with  respect  hereto  shall  be
          considered effective or enforceable unless in writing.

          Section  34.  Notices.  Any  notice  required  or  permitted  by or in
          connection with this GUARANTY shall be in writing and shall be made by
          facsimile  (confirmed  on the date the facsimile is sent by one of the
          other  methods of giving  notice  provided for in this  Section) or by
          hand delivery, by Federal Express, or other similar overnight delivery
          service, or by certified mail,  unrestricted delivery,  return receipt
          requested,  postage prepaid,  addressed to the LENDER or the GUARANTOR
          at the appropriate address set forth below or to such other address as
          may be  hereafter  specified  by  written  notice by the LENDER or the
          GUARANTOR.  Notice  shall  be  considered  given as of the date of the
          facsimile or the hand delivery, one (1) calendar day after delivery to
          Federal Express or similar overnight  delivery  service,  or three (3)
          calendar  days after the date of mailing,  independent  of the date of
          actual delivery or whether  delivery is ever in fact made, as the case
          may be,  provided  the giver of  notice  can  establish  the fact that
          notice was given as provided herein. If notice is tendered pursuant to
          the  provisions  of  this  Section  and is  refused  by  the  intended
          recipient thereof,  the notice,  nevertheless,  shall be considered to
          have been given and shall be effective as of the date herein provided.
         If to the LENDER:

                  NATIONAL BANK OF CANADA
                  125 West 55th Street
                  New York, New York 10019
         And
                  c/o NATIONAL BANK OF CANADA
                  401 E. Pratt Street, Suite 631
                  Baltimore, Maryland 21202
                  Attn: Robert A. Incorvati, Vice President
                  Facsimile: (410) 837-8359

         If to the GUARANTOR:

                  MANTECH INTERNATIONAL CORPORATION
                  12015 Lee Jackson Highway, 8th Floor
                  Fairfax, Virginia 22033
                  Attn.:   Tracy A. Wilson, Assistant Secretary
                  Fax No.:  (703) 218-8296

         With A Courtesy Copy To:

                  GOLDEN & NELSON, PLLC
                  8285 Highglade Court
                  Millersville, Maryland 21108
                  Attn.: Hedy L. Nelson, Esquire
                  Facsimile No.:  (410) 729-2246

          The  failure of the LENDER to send the above  courtesy  copy shall not
          impair  the  effectiveness  of notice  given to the  GUARANTOR  in the
          manner provided herein.

          Section 35. Binding  Nature.  This GUARANTY shall inure to the benefit
          of and be  enforceable  by the LENDER and the LENDERS  successors and
          assigns and any other  person to whom the LENDER may grant an interest
          in the  obligations  of the  BORROWERS  to the  LENDER,  and  shall be
          binding upon and enforceable against the GUARANTOR and the GUARANTORS
          successors, and assigns.

          Section 36. Assignability. This GUARANTY or an interest therein may be
          assigned by the LENDER,  or by any other  holder,  at any time or from
          time to  time,  without  any  prior  notice  to or  consent  from  the
          GUARANTOR.

          Section 37.  Final  Agreement.  This  GUARANTY  contains the final and
          entire agreement  between the LENDER and the GUARANTOR with respect to
          the guaranty by the  GUARANTOR of the  BORROWERS  obligations  to the
          LENDER. There are no separate oral or written  understandings  between
          the LENDER and the GUARANTOR with respect thereto.

          Section 38. Tense, Gender,  Defined Terms,  Captions.  As used herein,
          the plural  includes  the  singular,  and the  singular  includes  the
          plural. The use of any gender applies to any other gender. All defined
          terms  are  completely   capitalized  throughout  this  GUARANTY.  All
          captions are for the purpose of convenience only.

          Section 39. Seal And  Effective  Date.  This GUARANTY is an instrument
          executed under seal and is to be considered  effective and enforceable
          as of the date set forth on the first page hereof,  independent of the
          date of actual execution.

          Section 40. Waiver Of Trial By Jury. The GUARANTOR and the LENDER,  by
          their execution and acceptance,  respectively, of this GUARANTY, agree
          that any suit,  action, or proceeding,  whether claim or counterclaim,
          brought or  instituted  by either  party  hereto or any  successor  or
          assign of any party on or with  respect to this  GUARANTY  or which in
          any way  relates,  directly  or  indirectly,  to this  GUARANTY or any
          event,  transaction,  or  occurrence  arising  out  of or in  any  way
          connected  with this  GUARANTY,  or the  dealings of the parties  with
          respect  thereto,  shall be tried  only by a court  and not by a jury.
          EACH PARTY HEREBY EXPRESSLY WAIVES ANY RIGHT TO A TRIAL BY JURY IN ANY
          SUCH SUIT, ACTION, OR PROCEEDING.

          [Signatures Begin On Next Page]
          IN WITNESS WHEREOF,  the GUARANTOR has executed this GUARANTY with the
          specific intention of creating a document under seal.

          ATTEST/WITNESS: GUARANTOR:
                                            MANTECH INTERNATIONAL CORPORATION

          _________________________  By:            (SEAL)
                                                     Name:
                                                     Title:

         ACKNOWLEDGMENT

          COMMONWEALTH OF VIRGINIA, CITY/COUNTY OF _________________, TO WIT:

          I HEREBY  CERTIFY that on this ______ day of March,  2000,  before me,
          the  undersigned  Notary  Public  of  the  Commonwealth  of  Virginia,
          personally  appeared   __________________________,   and  acknowledged
          himself/herself  to  be  the  ___________________________  of  MANTECH
          INTERNATIONAL CORPORATION, a New Jersey corporation , and that he/she,
          as such, being authorized so to do, executed the foregoing  instrument
          for the  purposes  therein  contained  by signing  the name of MANTECH
          INTERNATIONAL       CORPORATION,       by      himself/herself      as
          ___________________________.

         IN WITNESS MY Hand and Notarial Seal.

                                               ___________________________(SEAL)
                                                 NOTARY PUBLIC
     My Commission Expires:
     ______________________

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