Document:

EXHIBIT 10.56

                         FORM OF STOCKHOLDERS' AGREEMENT

     STOCKHOLDERS'  AGREEMENT (this "Agreement"),  dated as of _______, 2001, by
and among Mobile Satellite  Ventures GP Inc., a Delaware  corporation  ("General
Partner")  and  General  Partner  of Mobile  Satellite  Ventures  LP, a Delaware
limited  partnership ("Newco LP") and the Stockholders of General Partner listed
on Schedule I hereto (each individually, a "Stockholder," and collectively,  the
"Stockholders", and together with General Partner, the "Parties").

                                    RECITALS

     WHEREAS, each Stockholder is also either a limited partner of Newco LP or a
holder of notes convertible into limited  partnership  interests in Newco LP and
owns a portion of the common  stock,  par value $0.01 per share (the "Stock") of
General  Partner in  proportionate  amounts based upon its respective  ownership
interests  in Newco LP (on an  as-converted  basis in the case of the holders of
the Convertible Notes); and

     WHEREAS,  the  Stockholders  have formed General Partner for the purpose of
having it serve exclusively as General Partner of Newco LP pursuant to the terms
of that certain Limited  Partnership  Agreement of Mobile Satellite Ventures LP,
dated as of [________ __, 2001], (the "Newco LP Agreement"); and

     WHEREAS,  the Stockholders wish to assure that General Partner performs its
duties under the Newco LP Agreement  and the other  agreements  by and among the
Stockholders strictly in accordance with the terms of this Agreement; and

     WHEREAS,  General  Partner  and the  Stockholders  are  entering  into this
agreement pursuant to the terms of that certain Amended and Restated  Investment
Agreement,  dated as of October __,  2001,  by and among the  Stockholders  (and
their  affiliates),  the LLC and certain other parties (as in effect on the date
hereof, and without giving effect to any modification,  amendment, supplement or
restatement thereof or waiver thereunder, the "October Investment Agreement");

     NOW, THEREFORE, in consideration of the agreements contained herein and for
other good and valuable  consideration,  the receipt and sufficiency of which is
hereby acknowledged, the Parties hereby agree as follows:

Section 1.  Definitions.  Initially  capitalized  terms  used,  but not  defined
herein,  shall have the meanings  ascribed thereto in the Newco LP Agreement or,
if not defined  therein,  in the October  Investment  Agreement,  as applicable.
Additionally,  terms  defined in this Section 1 shall,  for the purposes of this
Agreement, have the meanings herein specified.

     "Business  Day" means a day of the year on which banks are not  required or
authorized to close in New York City.

     "Columbia Investor Group" means the entities in Columbia Space (QP), Inc.'s
Investor Group as set forth in the October Investment Agreement.

     "Control Party" means (i) an Affiliate that has direct or indirect majority
voting control of a Limited Partner, or (ii) an Affiliate that has a majority of
its voting  interests held,  directly or indirectly,  by a Limited Partner or by
Persons that have direct or indirect voting control of a Limited Partner.

     "Excluded  Securities"  means any interests in the  Partnership  (i) issued
pursuant  to the  October  Investment  Agreement  or  any  of  the  transactions
contemplated  thereby,  (ii) issued in connection  with the  acquisition  of the
business of another entity, whether by the purchase of equity securities, assets
or  otherwise,  (iii)  issued as part of an  Initial  Public  Offering  or other
registered  underwritten public offering of the Partnership's  securities,  (iv)
issued under an employee  compensation plan approved by the General Partner, (v)
issued to financial institutions,  financial syndicates or lessors in connection
with bona fide commercial credit arrangements,  equipment financings, or similar
transactions for primarily other than equity financing purposes, and (vi) issued
pursuant to Section 8.1(h)(vi) of this Agreement.

     "Family Member" means, with respect to any Person (i) the spouse,  parents,
children,  siblings,  mother and father-in-law,  sons and  daughters-in-law  and
brothers and sisters-in-law of such Person or of any of the beneficial owners of
such Person, (ii) any trust whose  beneficiaries  consist of only one or more of
such Person and such  persons or (iii) any  partnership  or other  entity  whose
owners are one or more of such Person and such persons.

     "Intervening  Entity" shall mean, as applied to any Limited  Partner at any
time,  any Person the value of which at such time  consists  principally  of its
direct or indirect ownership of interests in, or obligations of, the Partnership
or Canadian Holdco. Without limiting the foregoing,  the parties stipulate that,
as of the date hereof, TMI and TMI's general partner are Intervening Entities.

     "Pledge  Agreement" means that certain Pledge  Agreement,  dated as of even
date  herewith,  by and among TMI,  TMI Sub and the other  parties  thereto,  as
amended, supplemented or revised from time to time.

     "Spectrum  Investor  Group"  means the  entities in Spectrum  Space  Equity
Investors  IV,  Inc.'s  Investor  Group as set forth in the  October  Investment
Agreement.

     "Telcom  Investor  Group" means the entities in Telcom  Satellite  Ventures
Inc.'s Investor Group as set forth in the October Investment Agreement.

Section 2.        Board Composition.
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     (a) Qualifications of Directors.  No person shall be elected or appointed a
director if that person is less than 18 years of age, is of unsound mind and has
been found so by a court, is not an individual, or has the status of a bankrupt.
Directors may, but need not, be Stockholders.

     (b) Each  Stockholder  agrees to use all  commercially  reasonable  efforts
(including  approving all necessary or advisable amendments to General Partner's
Certificate of  Incorporation  and/or Bylaws) to cause the board of directors of
General Partner (the "Board") to be composed as follows:

          (i)  Subject to clause  (ii)  below,  assuming  the First  Closing has
     occurred, the Board shall consist of twelve (12) directors as follows:

          (1) Each of the Telcom Investor Group, the Spectrum Investor Group and
          the Columbia  Investor  Group (or an Investor or group of Investors to
          which Limited Partners of any such Investor Group transferred at least
          a five percent (5%) Percentage Interest and expressly transferred such
          Investor  Group's right to designate a director  under this  Agreement
          (each such Person, an "Investor Group Assignee")),  acting through its
          respective Investor Group Designee, shall be entitled to designate one
          (1) director. For the avoidance of doubt, in no event shall the Telcom
          Investor Group, the Spectrum  Investor Group and the Columbia Investor
          Group,  or any  transferees  therefrom,  be entitled to designate more
          than three (3) directors in the aggregate.

          (2) Motient Sub shall be entitled to designate three (3) directors.

          (3) TMI Sub shall be entitled to designate three (3) directors.

          (4) The Note  Investors  shall be  entitled  to  designate  three  (3)
          directors.

          (ii) In the event that the Second Closing has not occurred on or prior
     to June 30, 2003,  then  beginning on July 1, 2003, the Board shall consist
     of ten (10) directors as follows:

          (1) The Telcom  Investor  Group,  the Spectrum  Investor Group and the
          Columbia  Investor Group (or an Investor Group Assignee),  as a group,
          shall be entitled to designate a total of one (1) director.

          (2) Motient Sub shall be entitled to designate three (3) directors.

          (3) TMI Sub shall be entitled to designate three (3) directors.

          (4) The Note  Investors  shall be  entitled  to  designate  three  (3)
          directors.

          (iii)  For so long as the  Spectrum  Investor  Group  continues  to be
     entitled  to  designate a director  under this  Agreement,  Spectrum  Space
     Equity Investors IV, Inc., a wholly-owned subsidiary of Spectrum Equity IV,
     L.P., shall be entitled to designate such director, and such director shall
     be a representative  of Spectrum Equity Investors IV, L.P.  Spectrum Equity
     Investors IV, L.P. shall be a third-party  beneficiary of this Agreement to
     the extent  necessary  in order to enforce  its rights  under this  Section
     2(b)(iii).

          (iv)  For so long  as the  Columbia  Investor  Group  continues  to be
     entitled to designate a director under this Agreement, Columbia Space (QP),
     Inc., a wholly-owned  subsidiary of Columbia  Capital Equity Partners (QP),
     L.P., shall be entitled to designate such director, and such director shall
     be a representative of Columbia Capital Equity Partners (QP), L.P. Columbia
     Capital Equity  Partners (QP),  L.P. shall be a third-party  beneficiary of
     this Agreement to the extent necessary in order to enforce its rights under
     this Section 2(b)(iv).

          (v) For so long as the  Note  Investors  continue  to be  entitled  to
     designate  directors  under  this  Agreement,  MSV  Investors  LLC shall be
     entitled  to  designate  such  directors,   and  such  directors  shall  be
     representatives of MSV Investors LLC.

     (c)  Resignation.  Any  director  may resign at any time by giving  written
notice to the President of General Partner (the  "President").  Such resignation
shall take  effect at the time  specified  in such notice or, if the time be not
specified,  upon receipt thereof by the President.  Unless  otherwise  specified
therein,  acceptance  of such  resignation  shall  not be  necessary  to make it
effective. In the event of the death, disability,  resignation or removal of any
director,  the Stockholder(s) which designated such director shall designate his
or her replacement.

Section 3.        Board Meeting.
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     (a) Regular  Meetings.  The Board shall meet no less often than  quarterly,
unless  otherwise  agreed by at least 4/5 of the Board.  Such meetings  shall be
held on such date as shall be  determined  by the President or a majority of the
Board.

     (b) Other Meetings. Other meetings of the Board shall be held at such times
as the Chairman of General Partner (the "Chairman"), the President or a majority
of the Board shall from time to time determine.

     (c) Notice of Meetings.  The Secretary of General Partner (the "Secretary")
shall give written  notice to the President and each director of each meeting of
the Board,  which notice shall state the place,  date,  time and purpose of such
meeting.  Notice of each such  meeting  shall be given to each  director,  if by
mail,  addressed to him at his  residence  or usual place of business,  at least
five (5) Business  Days before the day on which such  meeting is to be held,  or
shall be sent to him at such place by telecopy,  telegraph, cable, or other form
of recorded communication,  or be delivered personally or by telephone not later
than forty-eight (48) hours before the time at which such meeting is to be held;
provided,  however,  that if any  director  objects to the holding of such Board
meeting at the  requested  time and date,  such  meeting  shall be held five (5)
Business  Days  following the date of such notice.  A written  waiver of notice,
signed by the director  entitled to notice,  whether before or after the time of
the meeting  referred to in such waiver,  shall be deemed  equivalent to notice.
Neither the business to be transacted  at, nor the purpose of any meeting of the
Board, need be specified in any written waiver of notice thereof.  Attendance of
a director at a meeting of the Board shall constitute a waiver of notice of such
meeting.

     (d) Place of  Meetings.  The Board may hold its  meetings  at such place or
places within or without the State of Delaware as the President may from time to
time determine,  or as shall be designated in the respective  notices or waivers
of notice of such meetings.

     (e) Quorum and Manner of Acting.
     --------------------------------

     (1) A majority of the  directors  then in office (or who are members of any
     committee  of the  Board)  shall be  present  in  person or by proxy at any
     meeting of the Board (or a committee thereof,  as the case may be) in order
     to constitute a quorum for the transaction of business at such meeting, and
     the vote of a majority of those  directors,  or members of such  committee,
     present at any such meeting at which a quorum is present shall be necessary
     for the passage of any  resolution  or act of the Board or such  committee,
     except as  otherwise  expressly  required by this  Agreement or the October
     Investment  Agreement.  In the absence of a quorum for any such meeting,  a
     majority of the  directors  present  thereat may adjourn  such meeting from
     time to time until a quorum shall be present.

     (2) Organization.  At each meeting of the Board, one of the following shall
     act as  chairman  of the meeting and  preside,  in the  following  order of
     precedence:

          (1) the Chairman;

          (2) the President; or

          (3) any director chosen by a majority of the directors present.

The  Secretary  or, in the case of his absence,  any person whom the chairman of
the meeting  shall  appoint  shall act as secretary of such meeting and keep the
minutes thereof.

     (f)  Committees  of the Board.  The Board may,  by  resolution  passed by a
majority of the whole Board, designate one or more committees consisting of four
or more directors;  provided,  that each committee shall consist of at least one
Investor Group designee, one Motient Sub designee, one TMI Sub designee, and one
Note  Investor  designee.   Except  as  otherwise  expressly  required  by  this
Agreement,  any committee of the Board, to the extent provided in the resolution
of the Board  designating  such  committee,  shall have and may exercise all the
powers and authority of the Board in the  management of the business and affairs
of General Partner,  and may authorize the seal of General Partner to be affixed
to all papers  which may  require  it.  Each  committee  of the Board shall keep
regular minutes of its proceedings and report the same to Board and upon request
of the Stockholders, to the Stockholders.

     (g) Directors' Consent in Lieu of Meeting. Any action required or permitted
to be taken at any meeting of the Board or of any committee thereof may be taken
without a meeting,  without  prior  notice and  without a vote,  if a consent in
writing, setting forth the action so taken, shall be signed by all the directors
of the Board, in the case of a Board meeting, or all the members of a committee,
in the case of a committee  meeting,  and such consent is filed with the minutes
of the proceedings of the Board or such committee.

     (h) Action by Means of Telephone or Similar Communications  Equipment.  Any
one or more members of the Board, or of any committee  thereof,  may participate
in a meeting of the Board or such committee by means of conference  telephone or
similar communications  equipment by means of which all persons participating in
the meeting can hear each other,  and  participation  in a meeting by such means
shall constitute presence in person at such meeting.

     (i)  Compensation.  Directors  shall not receive any salary or compensation
for  their  services  as  directors  or as  members  of  committees,  except  as
authorized  by  Stockholders  holding a  majority  of the  shares of Stock  (the
"Shares").  The  directors  shall be entitled to be  reimbursed  for  travelling
expenses  properly  incurred by them in  attending  meetings of the Board or any
committee  thereof.  Nothing  herein shall  preclude  any director  from serving
General  Partner or Newco LP in any other  capacity and  receiving  compensation
therefor.

     (j) Selection of Officers. The initial officers of General Partner shall be
those set forth in General Partner's organizational  resolutions and any changes
thereto shall be approved by a vote of the majority of the Board members.

     (k) Agreements with Limited Partners or their  Affiliates.  Notwithstanding
the grant of  authority  to General  Partner  under  Section 6.1 of the Newco LP
Agreement,   without  the  prior   written   consent  of  the  majority  of  the
disinterested  directors  (or, if the majority of the directors are designees of
interested  parties,  the entire Board) and any prior written consent of Limited
Partners  of Newco LP required  by the Newco LP  Agreement,  the Board shall not
permit or cause General Partner or Newco LP to enter into  transactions with its
Limited  Partners or  Affiliates  of its Limited  Partners  except as  otherwise
permitted in the October Investment  Agreement;  provided that Newco LP shall be
permitted to enter into each of the other Ancillary Agreements.

     Section 4. Agreement to Vote Shares to Elect  Directors.  Each  Stockholder
hereby agrees to take all action  necessary  (including  voting or causing to be
voted,  or acting by written consent with respect to, any and all Shares held by
him or it on the record date for establishing the Stockholders  entitled to vote
for the  election  of  directors  of General  Partner)  to cause the  Investors'
designees,  the  Motient  Sub  designees,  the TMI Sub  designees,  and the Note
Investor designees to be elected to the Board, in accordance with the provisions
hereof.

     Section 5. Stockholder Meetings.
     --------------------------------

     (a)  Regular  Meetings.  The  Stockholders  shall  meet  annually,   unless
otherwise agreed by the Board. Such meetings shall be held on such date as shall
be determined by the a majority of the Board.

     (b) Special Meetings. Special meetings of the Stockholders shall be held at
such  times as the  Board,  the  President  or a  majority  in  interest  of the
Stockholders shall from time to time determine.

     (c) Notice of Meetings.  The  Secretary  shall give  written  notice to the
President and each Stockholder of each meeting of the Stockholders, which notice
shall state the place,  date,  time and purpose of such meeting.  Notice of each
such meeting shall be given to each Stockholder,  if by mail, to the address set
forth with respect to such Stockholder in Schedule I, at least five (5) Business
Days  before  the day on which such  meeting is to be held,  or shall be sent to
such  Stockholder  by  telecopy,  telegraph,  cable,  or other form of  recorded
communication,  or be  delivered  personally  or by  telephone  not  later  than
forty-eight  (48) hours  before  the time at which  such  meeting is to be held;
provided,  however,  that if any  Stockholder  objects  to the  holding  of such
Stockholder  meeting at the requested time and date,  such meeting shall be held
five (5) Business Days  following the date that such notice was given. A written
waiver of notice,  signed by the Stockholder entitled to notice,  whether before
or after the time of the  meeting  referred to in such  waiver,  shall be deemed
equivalent to notice.  Neither the business to be transacted at, nor the purpose
of any meeting of the  Stockholders  need be specified in any written  waiver of
notice  thereof.  Attendance of a Stockholder  at a meeting of the  Stockholders
shall constitute a waiver of notice of such meeting.

     (d) Place of Meetings.  The  Stockholders  may hold their  meetings at such
place or places  within or without the State of Delaware  as the  President  may
from time to time determine, or as shall be designated in the respective notices
or waivers of notice of such meetings.

     (e) Quorum and Manner of Acting.  The Stockholders  holding the majority of
the  Shares  shall be  present  in  person  or by proxy  at any  meeting  of the
Stockholders  in order to constitute a quorum for the transaction of business at
such  meeting,  and,  except as  otherwise  provided  herein  or in the  October
Investment  Agreement,  the vote of those Stockholders holding a majority of the
Shares,  present  at any such  meeting  at which a quorum is  present,  shall be
necessary for the passage of any resolution or act of the  Stockholders,  except
as otherwise  expressly  required by this Agreement.  In the absence of a quorum
for any such meeting,  holders of a majority of the Shares  present  thereat may
adjourn such meeting from time to time until a quorum shall be present.

     (f)  Stockholders'  Consent  in Lieu of  Meeting.  Any action  required  or
permitted to be taken at any meeting of the  Stockholders may be taken without a
meeting,  without  prior  notice and  without a vote,  if a consent in  writing,
setting forth the action so taken,  shall be signed by the Stockholders  holding
the  requisite  number of Shares  for the taking  the  relevant  action and such
consent is filed with the minutes of the proceedings of the Stockholders.

     (g) Action by Means of Telephone or Similar Communications  Equipment.  Any
one or more  Stockholders  may  participate in a meeting of the  Stockholders by
means of conference  telephone or similar  communications  equipment by means of
which  all  persons  participating  in the  meeting  can hear  each  other,  and
participation in a meeting by such means shall constitute  presence in person at
such meeting.

     Section  6.  Assignment;   Restriction  on  Transfer.  The  rights  of  the
     -----------------------------------------------------
Stockholders to designate directors hereunder may not be transferred,  except by
Investors to an Investor Group Assignee in accordance with Section 2(b)(i)(1).

     Section 7.  Transfer of Shares; Redemption.
     -------------------------------------------

     (a)  Transfer  of Shares.  The  Stockholders  each  undertake  to take such
actions  and  execute  such  documents  as may be  necessary  to insure that the
proportionate   ownership  of  General   Partner  at  all  times   reflects  the
then-current proportional ownership of Limited Partnership Interests in Newco LP
(on an as-converted basis in the case of the holders of the Convertible  Notes).
In furtherance of the foregoing,  except for Transfers made  simultaneously with
permitted transfers of Limited Partnership Interests made in accordance with the
terms  of  Section  8 of  this  Agreement  or  Articles  3 and 7 of the  October
Investment  Agreement,  each Stockholder  agrees not to, directly or indirectly,
sell, assign,  transfer,  pledge, encumber,  hypothecate,  mortgage or otherwise
dispose of, either  voluntarily or involuntarily (or to enter into any contract,
option or other  arrangement  or  understanding  to do any of the  foregoing) (a
"Transfer"),  any Shares; provided,  however, that TMI Sub shall be permitted to
pledge  its  Shares  pursuant  to  the  Pledge  Agreement.   In  addition,  each
Stockholder  hereby undertakes to, at the same time that it transfers any of its
Limited Partnership  Interests or Convertible Notes, Transfer its Shares (or the
same portion thereof as the Limited  Partnership  Interests or Convertible Notes
being  transferred  bear  to its  total  Limited  Partnership  Interests  (on an
as-converted basis in the case of the holders of the Convertible  Notes)) to the
purchaser or assignee of any of its Limited Partnership Interests or Convertible
Notes  in  accordance  with  Section  8 of  this  Agreement  or  the  applicable
provisions of the Convertible Notes.  Following a Transfer of such Shares,  such
Shares  shall  remain  subject  to the  provisions  of this  Agreement,  and the
transferee  shall execute and deliver to General Partner a written  agreement to
be bound by this  Agreement in form and  substance  reasonably  satisfactory  to
General Partner.  Notwithstanding the foregoing,  except as set forth in Section
2(b)(i)(1)  with  respect  to  Transfers  to  an  Investor  Group  Assignee,  in
connection with transfers of Limited Partnership  Interests pursuant to Sections
8.2(c) or (d) of this Agreement, no transferee shall have the right to designate
directors pursuant hereto.

     (b) Redemption;  Effect of Redemption and Transfer. In the event that Newco
LP repays any of the principal amount of Convertible Notes, in whole or in part,
General Partner shall purchase from each Note Investor whose  Convertible  Notes
are being repaid (in whole or in part), and each Note Investor whose Convertible
Notes are being  repaid (in whole or in part) shall sell to General  Partner,  a
number  of Shares  equal to the  product  of (I) the sum of the total  number of
Shares issued to such Note Investor by General Partner  (appropriately  adjusted
for stock splits, combinations,  stock dividends,  reorganizations and the like)
multiplied by (II) a fraction,  the numerator of which shall equal the amount of
principal of such Note Investor's  Convertible  Note so paid and the denominator
of which shall equal the original principal amount of such Convertible Note. The
consideration  for any such  purchase  shall be $0.01  per  Share,  and the Note
Investor  holding such Shares shall  deliver such Shares to General  Partner for
cancellation promptly following any such repayment.  Additionally,  in the event
that:

          (i)  Newco LP repays  in cash a total of more  than  one-third  of the
     original  aggregate  principal amount of the Convertible Notes, the size of
     the Board shall be reduced by one (1) director,  the Note  Investors  shall
     only be entitled to designate  two (2)  directors,  and the Note  Investors
     shall cause one (1) of the directors  designated by them to resign from the
     Board;

          (ii)  Newco LP repays in cash a total of more than  two-thirds  of the
     original  aggregate  principal amount of the Convertible Notes, the size of
     the  Board  shall  be  reduced  by a total of two (2)  directors,  the Note
     Investors shall only be entitled to designate one (1) director and the Note
     Investors shall cause all directors designated by them, other than such one
     (1) remaining director, to resign from the Board; and

          (iii)  Newco LP  repays in cash a total of more  than  ninety  percent
     (90%) of the original aggregate  principal amount of the Convertible Notes,
     the size of the Board  shall be reduced by a total of three (3)  directors,
     the Note Investors  shall not be entitled to designate any  directors,  the
     Note Investors shall not be entitled to designate any directors to serve on
     committees  of the Board and the Note  Investor  shall cause all  directors
     designated by them to resign from the Board.

     Section 8 Transfers, Admission of Limited Partners and Conversion.
     -------------------------------------------------------

     Section 8.1  Additional Issuances of Interests.
                   ---------------------------------

     (a) In order to raise capital for Newco LP operations or to acquire assets,
to redeem or retire  Newco LP debt,  or for any other valid  Newco LP  purposes,
General Partner may, subject to the provisions of this Section 8.1, from time to
time determine that it is in the best interests of Newco LP to cause Newco LP to
issue additional  interests in Newco LP to the Limited Partners or other Persons
and to admit  such  other  Persons to Newco LP as  Additional  Limited  Partners
pursuant to Section 8.4. General Partner shall determine the  consideration  for
and the terms and conditions with respect to any future issuance of interests in
Newco LP.

     (b)  Subject  to clause  (h)  below,  General  Partner  shall not issue any
interests in Newco LP unless it first delivers to each Limited  Partner and Note
Investor (each such Person being referred to in this Section 8.1 as a "Buyer") a
written  notice (the  "Notice of  Proposed  Issuance")  specifying  the type and
amount of such  interests  that Newco LP then  intends  to issue  (the  "Offered
Interests"),  all of the material terms,  including the price (cash or non-cash)
upon which Newco LP proposes to issue the Offered Interests and stating that the
Buyers  shall have the right to  purchase  the Offered  Interests  in the manner
specified  in this  Section  8.1 for the same price per share and in  accordance
with  the same  terms  and  conditions  specified  in such  Notice  of  Proposed
Issuance,  provided,  that if such price consists of non-cash  consideration,  a
Buyer  may  purchase  the  Offered  Interest  with the same  type and  amount of
non-cash  consideration  described  in such Notice of Proposed  Issuance or, may
instead, pay for such Offered Interests with the cash equivalent of such price.

     (c) During the ten (10) consecutive day period commencing on the date Newco
LP delivers to all of the Buyers the Notice of Proposed  Issuance  (the "Ten Day
Period"),  the Buyers shall have the option to purchase up to all of the Offered
Interests at the same price and upon the same terms and conditions  specified in
the  Notice of  Proposed  Issuance.  Each Buyer  electing  to  purchase  Offered
Interests must give written  notice of its election to General  Partner prior to
the expiration of the Ten Day Period.

     (d) Each Buyer shall have the right to purchase  up to that  percentage  of
the Offered Interests equal to the Percentage  Interest then held by such Buyer.
The amount of such  Offered  Interests  that each Buyer is  entitled to purchase
under this Section 8.1 shall be referred to as its "Proportionate Share."

     (e) Each  Buyer  shall  have a right of  oversubscription  such that if any
other Buyer fails to elect to purchase  his or its full  Proportionate  Share of
the Offered  Interests,  the other Buyer(s) shall, among them, have the right to
purchase up to the  balance of such  Offered  Interests  not so  purchased.  The
Buyers may exercise such right of  oversubscription by electing to purchase more
than their  Proportionate  Share of the Offered  Interests by so  indicating  in
their written notice given during the Ten Day Period.  If, as a result  thereof,
such oversubscription elections exceed the total number of the Offered Interests
available in respect to such  oversubscription  privilege,  the  oversubscribing
Buyers shall be cut back with respect to  oversubscriptions  on a pro rata basis
in accordance with their respective Proportionate Share or as they may otherwise
agree among themselves.

     (f) If all of the Offered  Interests  have not been purchased by the Buyers
pursuant to the foregoing provisions, then General Partner shall have the right,
until the expiration of one hundred eighty (180)  consecutive days commencing on
the first day  immediately  following the  expiration of the Ten Day Period,  to
issue the Offered Interests not purchased by the Buyers at not less than, and on
terms no more  favorable in any  material  respect to the  purchaser(s)  thereof
than, the price and terms specified in the Notice of Proposed Issuance.  If such
remaining  Offered Interests are not issued within such period and at such price
and on such terms,  the right to issue in accordance with the Notice of Proposed
Issuance shall expire and the provisions of this Agreement  shall continue to be
applicable to the Offered Interests.

     (g) Notwithstanding the foregoing, the rights described in this Section 8.1
shall not apply with respect to the issuance of Excluded Securities.

     (h)  Notwithstanding  the foregoing,  General  Partner may proceed with the
issuance of interests in Newco LP without  first  following  the  procedures  in
clauses  (b)-(f) above,  provided that the purchaser of such interests (the "New
Purchaser")  agrees in writing to take such interests  subject to the provisions
of this Section 8.1(h). In such event the following provisions shall apply:

          (i) Within ten (10) days  following  the  issuance of such  interests,
     General  Partner or the New  Purchaser  shall issue to each Buyer a written
     notice (the "Notice of  Issuance")  specifying  the type and amount of such
     interests  that Newco LP has issued (the  "Issued  Interests"),  all of the
     material terms,  including the price (the "Issued Interest Price") at which
     Newco LP issued the Issued Interests and stating that the Buyers shall have
     the right to purchase  Issued  Interests in the manner  specified below for
     the same  price  per  Unit  and in  accordance  with  the  same  terms  and
     conditions specified in such Notice of Issuance.

          (ii) During the ten (10) consecutive day period commencing on the date
     Newco LP or the New  Purchaser  delivers to all of the Buyers the Notice of
     Issuance (the "Issuance Ten Day Period"),  the Buyers shall have the option
     to purchase up to all of the Issued  Interests for the same type and amount
     per  Issued  Interest  of cash or  non-cash  consideration  paid by the New
     Purchaser or cash in an amount  equivalent in value to the Issued  Interest
     Price and upon the same  terms and  conditions  specified  in the Notice of
     Issuance.  Each Buyer  electing  to  purchase  Issued  Interests  must give
     written  notice of its election to the  deliverer of the Notice of Issuance
     prior to the expiration of the Issuance Ten Day Period.

          (iii)  Each  Buyer  shall  have  the  right to  purchase  from the New
     Purchaser  up to that  percentage  of the  Issued  Interests  equal  to the
     Proportionate Share held by such Buyer immediately prior to the issuance of
     the Issued Interests.

          (iv) Each Buyer  shall have a right of  oversubscription  such that if
     any other Buyer fails to elect to  purchase  his or its full  Proportionate
     Share of the Issued Interests,  the other Buyer(s) shall,  among them, have
     the right to purchase up to the  balance of such  Issued  Interests  not so
     purchased.  The  Buyers may  exercise  such  right of  oversubscription  by
     electing  to  purchase  more than their  Proportionate  Share of the Issued
     Interests  by so  indicating  in their  written  notice  given  during  the
     Issuance Ten Day Period.  If, as a result  thereof,  such  oversubscription
     elections  exceed the total  number of the Issued  Interests  available  in
     respect to such  oversubscription  privilege,  the  oversubscribing  Buyers
     shall be cut back with respect to  oversubscriptions on a pro rata basis in
     accordance  with  their  respective  Proportionate  Share  or as  they  may
     otherwise agree among themselves.

          (v) Any Issued  Interests  that have not been  purchased by the Buyers
     pursuant  to the  foregoing  provisions  shall  remain  owned  by  the  New
     Purchaser.

          (vi) Notwithstanding  anything in this clause (h) to the contrary,  in
     the event the Buyers elect, within the Issuance Ten Day Period, to purchase
     less  than  all of  the  Issued  Interests  then,  in  lieu  of the  Buyers
     purchasing  Issued  Interests from the New Purchaser,  General  Partner may
     elect to issue  directly to such  Buyers,  for the same type and amount per
     Issued Interest of cash or non-cash consideration paid by the New Purchaser
     or cash in an amount  equivalent in value to the Issued  Interest Price, an
     equivalent amount of additional securities that are identical to the Issued
     Interests in all material respects.

     Section 8.2 Transfers. Except as set forth in Sections 8.2(c) and (d) or in
the October Investment  Agreement,  until September 30, 2002, no Limited Partner
or Note Investor  shall be permitted to transfer any of its Limited  Partnership
Interests or  Convertible  Notes to any Person without the consent of a majority
in interest  (determined on an as-converted  basis) of the Limited  Partners and
Note Investors who are neither  transferors nor  transferees,  nor members of an
Investor Group which includes a transferee or  transferor.  After  September 30,
2002, no Limited Partner or Note Investor may assign or transfer all or any part
of its Limited Partnership  Interest or Convertible Notes to any Person,  except
in compliance with the following:

     (a) Right of First Refusal.  In the event that after  September 30, 2002, a
Limited Partner or Note Investor (a "Selling Party") proposes to transfer all or
a portion of its Limited Partnership  Interest or Convertible Notes to any third
party,  other than in accordance with Section 8.2(c) or (d),  pursuant to a bona
fide offer,  such Selling Party will provide  notice of such  proposed  transfer
(including the identity of the proposed  purchaser of such interest,  the amount
of interests or Convertible  Notes  proposed to be transferred  and the proposed
terms  thereof)  (the  "Transfer  Notice"),  at least fifteen (15) Business Days
prior to the proposed transfer, to each other Limited Partner and Note Investor,
whereupon  each other Limited  Partner and Note Investor shall have the right to
purchase,  at the same price and upon the same terms and conditions set forth in
the Transfer  Notice,  a pro rata portion of such interest or  Convertible  Note
based upon such Limited  Partner's or Note Investor's  portion of the Percentage
Interests  (determined on an  as-converted  basis with respect to holders of the
Convertible  Notes) held by all Limited  Partners and Note Investors  other than
the Selling Party. Except as set forth in the next sentence,  the purchase price
shall be payable in cash.  In the event that the Transfer  Notice  specifies the
payment of  consideration  other than cash,  the purchase  price for purposes of
this  Section   8.2(a)  shall  either  be  (x)  the  cash   equivalent  of  such
consideration,  determined by General Partner in good faith or (y) to the extent
the  participating  Limited Partner or Note Investor  elects,  the same type and
amount of non-cash consideration that is proposed to be paid as described in the
Transfer Notice.  The Transfer Notice shall  constitute an irrevocable  offer by
the Selling Party to sell to the other Limited  Partners and Note Investors such
interests  or  Convertible  Notes at the price and on the terms as  contained in
such  Transfer  Notice.  Each  Limited  Partner  or Note  Investor  desiring  to
participate  in such  purchase  shall  provide the Selling  Party and each other
Limited  Partner and Note Investor  notice of its agreement to participate  (the
"Participation Notice") within ten (10) Business Days of receipt of the Transfer
Notice  specifying such  participation  and whether and the extent to which such
Limited  Partner or Note Investor  wishes to acquire any remaining,  unallocated
portion of the proposed transfer (the "Unallocated  Portion"). In the event that
one or more of the other  Limited  Partners or Note  Investors  do not provide a
timely  Participation  Notice, the Unallocated Portion shall be allocated in pro
rata  proportion  to  the  Percentage  Interest  (after  giving  effect  to  the
conversion of the  Convertible  Notes) held by each of the Limited  Partners and
Note Investors who submits a Participation  Notice to the extent of such Limited
Partner's or Note  Investor's  indicated  willingness to acquire any Unallocated
Portion as provided in such Limited  Partners' or Note Investor's  Participation
Notice. The Participation Notice shall be deemed to be an irrevocable commitment
to  purchase  from the  Selling  Party,  at the  price  (or the cash  equivalent
thereof) and on the terms as contained in the Transfer Notice, the amount of the
interests  or  Convertible  Notes that such  Limited  Partner  or Note  Investor
specifies in the Participation Notice. In the event that the Limited Partners or
Note  Investors are not willing to purchase all of the interests or  Convertible
Notes offered pursuant to the Transfer Notice, and the amount of interests which
the Selling Party has offered to sell  pursuant to the Transfer  Notice less the
amount of interests or Convertible Notes the Limited Partners and Note Investors
are  willing  to  accept  is less  than  the  minimum  amount  of  interests  or
Convertible  Notes which the offeror is willing to purchase pursuant to the bona
fide offer described in the Transfer Notice,  then the Limited Partners and Note
Investors  shall be deemed to have rejected the offer  contained in the Transfer
Notice in its entirety and the Selling  Party shall be permitted to proceed with
the sale  described  in the  Transfer  Notice.  In the  event  that the  Limited
Partners and Note Investors  shall have accepted all or part of the interests or
Convertible  Notes offered  pursuant to the Transfer  Notice (and shall not have
been  deemed to have  rejected  the offer in its  entirety as  described  in the
immediately  preceding  sentence),  then the  Selling  Party  shall sell to such
Limited Partners and Note Investors such interests or Convertible  Notes as have
been accepted by such Limited  Partners and Note  Investors as specified in such
Limited Partner's or Note Investor's Participation Notice on the terms contained
in the  Transfer  Notice.  Any  interests or  Convertible  Notes not sold to the
Limited  Partners or Note  Investors  pursuant to the preceding  sentence may be
sold to a third  party,  including  the original  offeror,  at a price not lower
than,  and on such other terms and  conditions  not more favorable to such third
party than, those contained in the original  Transfer Notice, at any time within
one hundred eighty (180) days after the expiration of the offer required by this
Section  8.2(a).  In the  event  the  interests  or  Convertible  Notes  are not
transferred  by the Selling  Party on such terms during such one hundred  eighty
(180) day period,  the  restrictions  of this Section  8.2(a) shall again become
applicable  to any  transfer of interests  or  Convertible  Notes by the Selling
Party.

     (b)  Tag Along Rights.
          ----------------

          (i) General.  No Selling  Party may transfer  (other than  pursuant to
     Section 8.2(c) or 8.2(d)) Limited  Partnership  Interests or any portion of
     the Convertible Notes held by such Selling Party to any Person,  unless the
     terms and  conditions of such transfer  shall include an offer by the third
     party  transferee to the other Limited Partners and Note Investors (each, a
     "Tag Along Participant"),  at a price calculated using the same methodology
     used to  calculate  the price of the Selling  Party's  Limited  Partnership
     Interest taking into account the relative capital accounts and distribution
     rights of the Tag Along  Participants,  or, with respect to the Convertible
     Notes,  at a purchase  price per Unit  calculated  by dividing the purchase
     price of such offer  divided  by the number of Common  Units into which the
     portion  of  such  Convertible  Note  proposed  to be  transferred  is then
     convertible  (such price,  the "Tag Along Price") and on the same terms and
     conditions as the Selling Party has agreed to sell its Limited  Partnership
     Interest or portion of such Convertible Note, to include in the transfer to
     the third party transferee a portion of Limited Partnership Interests,  or,
     with  respect  to  transfers  of  Convertible  Notes,  a  number  of  Units
     determined in accordance with this Section 8.2(b).

          (ii) Obligation of Transferee to Purchase.  The third-party transferee
     of the Selling  Party shall  purchase from each Tag Along  Participant  the
     portion of such Tag Along  Participant's  Limited  Partnership  Interest or
     Convertible Note that such Tag Along Participant  desires to sell, provided
     that such portion does not exceed the Maximum Tag Along Portion (as defined
     below) and, if such  portion  exceeds  the Maximum Tag Along  Portion,  the
     transferee shall purchase only the Maximum Tag Along Portion.  For purposes
     hereof, the term "Maximum Tag Along Portion" means a portion of a Tag Along
     Participant's Limited Partnership Interest or Convertible Note the price of
     which (based on the Tag Along Price of such Limited Partnership Interest or
     Convertible  Note) equals the total  original  price proposed to be paid by
     the  transferee for the Selling  Party's  Limited  Partnership  Interest or
     portion of a Convertible  Note  multiplied by a fraction,  the numerator of
     which  is the Tag  Along  Price  of  such  portion  which  such  Tag  Along
     Participant desires to include in such sale and the denominator of which is
     the  aggregate  Tag Along Price of the  Limited  Partnership  Interests  or
     portion of a  Convertible  Note that the  Selling  Party and each Tag Along
     Participant desires to include in such sale.

          (iii) Exercise. The tag-along right may be exercised by each Tag-Along
     Participant  by delivery of a written notice to the Selling Party (the "Tag
     Along Notice")  within 15 calendar days  following  receipt of the Transfer
     Notice.  The  Tag  Along  Notice  shall  state  the  portion  of a  Limited
     Partnership  Interest or Convertible  Note that such Tag Along  Participant
     wishes to include in such transfer to the transferee.  Upon the giving of a
     Tag  Along  Notice,  such  Tag  Along  Participant  shall be  entitled  and
     obligated  to sell the  portion  of its  Limited  Partnership  Interest  or
     Convertible  Note set forth in the Tag Along Notice,  to the  transferee on
     the terms and conditions set forth in the Transfer Notice (the  "Transferee
     Terms"); provided, however, the Selling Party shall not consummate the sale
     of any Limited  Partnership  Interest or Convertible  Note offered by it if
     the  transferee  does not purchase all Limited  Partnership  Interests  and
     portions of Convertible  Notes which each Tag Along Participant is entitled
     and  desires  to  sell  pursuant   hereto.   After  expiration  of  the  15
     calendar-day  period  referred to above,  if the provisions of this Section
     have been  complied  with in all  respects,  the Selling Party and each Tag
     Along  Participant  that  delivered a Tag Along Notice  shall  transfer the
     Limited Partnership  Interests and portions of Convertible Notes determined
     in accordance  with Section  8.2(b)(ii) to the transferee on the Transferee
     Terms on the sale date proposed in the Transfer  Notice (or such other date
     within  sixty (60) days of such  proposed  sale date as may be agreed among
     the participants in such transfer).

          (iv)  Several  Liability.  Anything to the contrary  contained  herein
     notwithstanding,  the Selling Party agrees to use its reasonable good faith
     efforts to seek to ensure that the applicable  Transferee Terms provide for
     several, and not joint, liability,  with respect to the indemnification and
     comparable obligations contained within such Transferee Terms.

     (c)  Subject to  Sections  8.2(e),  (f) and (g), a Limited  Partner or Note
Investor  may at any time and from time to time (i) transfer all or part of such
Limited Partner's Limited  Partnership  Interest or Note Investor's  Convertible
Notes  to any of such  Limited  Partner's  or  Note  Investor's  Family  Members
provided  that such Limited  Partner or Note  Investor  shall  provide the other
Partners  and Note  Investors  notice  of the  identity  of such  Family  Member
transferee,  (ii)  transfer all or part of its Limited  Partnership  Interest or
Convertible  Notes  to its  members,  partners,  shareholders  or  other  equity
holders,  as the case may be  ("Distributee"),  pro-rata in accordance  with the
governing documents of the Limited Partner or Note Investor, as the case may be,
and  without  consideration,  or  (iii)  transfer  all or part  of such  Limited
Partner's  Limited  Partnership  Interest  to a  Control  Party of such  Limited
Partner or of such Note Investor's  Convertible Notes to a Control Party of such
Note Investor;  provided, that such Limited Partner or Note Investor and Control
Party agree with Newco LP in writing that such Control Party shall transfer such
Limited  Partnership  Interest or Convertible Notes back to such Limited Partner
or Note Investor  immediately  upon such Person ceasing to be a Control Party of
such Limited Partner or Note Investor. A Limited Partner or Note Investor may at
any time and from time to time pledge or  hypothecate,  in  connection  with its
bona fide financing arrangements  (including,  in the case of Motient, under its
current  guaranteed  bank  facilities),  its  Limited  Partnership  Interest  or
Convertible  Notes,  provided,  that upon  foreclosure or other execution of the
pledge or hypothecation, any assignment or transfer shall be subject to Sections
8.2(e),  (f) and (g). Subject to Sections 8.2(e), (f) and (g), a Class A Limited
Partner  may at any  time  and  from  time to time  transfer  all or part of its
Limited Partnership Interest to another Class A Limited Partner.

     (d) Each of TMI Sub,  Motient Sub and the Lead Note Investor shall have the
right,  subject to Sections 8.2(a), (e), (f), and (g), to assign or transfer its
interest in Newco LP to any Person owning 10% or more of the outstanding  common
stock of BCE Inc.,  Motient or Rare Medium Group,  Inc.  respectively,  and each
other Limited  Partner shall have the right,  subject to Sections  8.2(a),  (e),
(f),  and (g),  to assign or  transfer  its  interest  in Newco LP to any Person
owning ten percent  (10%) or more of the  ownership  interests  in such  Limited
Partner;  provided  that in the case of a transfer by TMI Sub,  such  transferee
agrees  to be bound by the  terms  and  conditions  of (i) the  Non-Interference
Agreement,  of the  date  even  herewith  between  BCE  Inc.  and  Newco LP (the
"Non-Interference  Agreement")  applicable  to BCE Inc.,  (ii) the  Stockholders
Agreement,  of the date even  herewith,  by and among  TMI,  Newco LP,  Canadian
Holdco and Canadian License Co. and (iii) the Pledge Agreement.

     (e) In addition to any other  requirements of this Agreement  relating to a
transfer of Limited  Partnership  Interests  or  Convertible  Notes,  no Limited
Partnership Interest or Convertible Note shall be transferred or assigned unless
the  transferee  (i)  executes an  instrument  satisfactory  to General  Partner
accepting all of the terms and conditions  relating to a Limited Partner or Note
Investor set forth in this  Agreement and the Newco LP Agreement,  (ii) pays any
reasonable  expenses of Newco LP incurred in  connection  with such  transfer or
assignment (including, without limitation,  attorney's fees) and (iii) is either
an  "accredited  investor"  (as  defined  in  Rule  501  promulgated  under  the
Securities  Act of 1933,  as amended  (the  "Securities  Act")) or  provides  an
opinion of counsel  reasonably  acceptable to General  Partner that the transfer
will not require registration under the Securities Act.

     (f) Notwithstanding any other provisions of this Agreement to the contrary,
General  Partner  may  prohibit  any  proposed  transfer  if, in the  reasonable
determination  of the General  Partner,  such  transfer  would (i) result in the
close of Newco LP's taxable year with  respect to all Limited  Partners,  in the
termination  of Newco LP within the meaning of ss.  708(b) of the Code or in the
termination of its status as a partnership  under the Code,  (ii) cause Newco LP
to be in violation of any applicable  state or federal  securities laws or (iii)
result in an interest in Newco LP being held by a Person whose  participation in
the ownership of Newco LP would be detrimental to Newco LP;  provided,  however,
that no  transfer  made  pursuant  to  Section  8.2(c)  hereof  shall be  deemed
detrimental to Newco LP.

     (g) To the  extent  that any  regulatory  approval,  notification  or other
submission or procedure is required or customarily  provided in connection  with
the exercise of any right or  obligations  as set forth in this Agreement or the
Newco LP Agreement  with respect to the transfer or  assignment  of interests in
Newco LP (including,  but not limited to, FCC approvals (if  required),  filings
under the HSR Act and applicable  securities  laws), such transfer or assignment
pursuant to this  Agreement  will be delayed and will only take place after such
approval,  notification  or other  submission  or procedure  has been  obtained,
submitted or completed, as determined by General Partner.

     (h) In  addition  to any other  restrictions  regarding  TMI Sub's right to
transfer the Limited Partnership Interests held by it contained herein or in any
Ancillary  Agreement,  TMI Sub shall not be  permitted  to transfer  its Limited
Partnership  Interests  except to a Person (or an Affiliate of such Person) that
is also simultaneously acquiring TMI's direct or indirect ownership interests in
Canadian  Holdco and Canadian  License Co. Any  purported  transfer of TMI Sub's
Limited  Partnership  Interests in contravention of this subsection (h) shall be
void and of no effect.

     (i) Any transfer of Limited Partnership Interests hereunder shall be deemed
to  include a  proportional  transfer  of the  transferor's  Units  and  Capital
Account,  adjusted for all prior allocations and  distributions  with respect to
the  transferred  Capital  Account for  purposes of Articles VII and VIII of the
Newco LP Agreement.

     (j) Except as set forth in the last  sentence of this  paragraph,  (1) upon
any transfer of Class A Preferred Units and Limited  Partnership  Interests by a
Class A Limited  Partner to Motient Sub,  TMI Sub or any  Affiliate of either of
them,  or (2) if any Class A Preferred  Units  otherwise  become held by Motient
Sub, TMI Sub or any  Affiliate of either of them,  except with the prior written
consent  of the Class A Limited  Partners  other than the  transferring  Class A
Limited  Partner,  none of Motient  Sub,  TMI Sub or any  Affiliate of either of
them,  shall be deemed to be a Class A Limited  Partner or shall be  entitled to
vote as a Class A Limited Partner and the Class A Preferred Units so acquired or
held shall  automatically  convert  into the number of Common Units which at the
time of such conversion equals the Percentage Interest  represented by the Class
A Preferred Units so acquired.  Notwithstanding the foregoing, in the event that
any of Motient Sub, TMI Sub, or any  Affiliates  of either of them pay a portion
of the Investor  Purchase Price at the Second Closing pursuant to Section 2.3 of
the October  Investment  Agreement,  such Units purchased by such Persons at the
Closing  shall be Class A  Preferred  Units and shall  not be  converted,  or be
deemed to have been  converted,  into Common  Units by operation of this Section
8.2(j).

     (k) For purposes of this  Agreement,  the sale or transfer of any equity or
other ownership  interests in any  Intervening  Entity (an  "Intervening  Entity
Ownership  Change")  shall be deemed to  constitute a transfer of the  aggregate
Limited  Partnership  Interests  held by that Limited  Partner or the  aggregate
amount of  Convertible  Notes owned  directly or indirectly by such  Intervening
Entity  multiplied  by a  fraction,  the  numerator  of which is the  percentage
ownership of the  Intervening  Entity so sold or transferred and the denominator
of which is 100%. If such a deemed transfer of Limited Partnership  Interests or
Convertible  Notes  occurs  without  compliance  with  the  provisions  of  this
Agreement then, without limiting the rights of Newco LP or the other Partners or
Note  Investors  at law or in  equity,  all of the  Limited  Partners  and  Note
Investors (other than the Limited Partner which is so deemed to have transferred
Limited  Partnership  Interests  or Note  Investor  deemed  to have  transferred
Convertible  Notes)  shall have the right to purchase  the  Limited  Partnership
Interests  or  Convertible  Notes  so  deemed  transferred  as if  such  Limited
Partnership  Interests or Convertible Notes were being offered for sale pursuant
to the  provisions  of  Section  8.2(a)  (the  provisions  of which  are  hereby
incorporated   by   reference,   mutatis   mutandis)  for  the  same  amount  of
consideration to be given to the Intervening Entity or its owners, in respect of
the Intervening Entity Ownership Change.

     (l) Any  attempted  transfer of Units,  Limited  Partnership  Interests  or
Convertible Notes in violation of this Agreement shall be void and of no effect.

Section 8.3 Admission of Substituted Limited Partners.

     (a) An  assignee  or  transferee  of an  interest  in Newco LP shall not be
admitted to Newco LP as a substituted Limited Partner until (i) such assignee or
transferee  and  transferring  Limited  Partner  has  complied  with  all of the
conditions  and  procedures  set forth in Section  8.2 , (ii) such  assignee  or
transferee has confirmed in writing to General  Partner that it has reviewed the
terms and  conditions of this  Agreement,  the Newco LP  Agreement,  the October
Investment  Agreement and each of the Ancillary  Agreements  including,  without
limitation,  the events of  default,  remedy and  forfeiture  provisions  of the
Pledge  Agreement,  and (iii)  payment of any  reasonable  expenses  of Newco LP
incurred in  connection  with such  admission  (including,  without  limitation,
attorney's fees). Such assignee or transferee shall automatically be admitted to
Newco LP as a Limited Partner  following  satisfaction of the provisions of this
Section 8.3(a).

     (b) A Person who  acquires any Limited  Partnership  Interests of a Limited
Partner pursuant to Section 8.2 but who is not admitted as a substituted Limited
Partner  pursuant to Section  8.3(a) shall be entitled only to  allocations  and
distributions  with respect to such acquired  Limited  Partnership  interests in
accordance with this Agreement,  but shall have no right to vote or give consent
hereunder,  to obtain any  information or accounting of the affairs of Newco LP,
shall not  solely as a result of its  acquisition  of such  Limited  Partnership
Interests  obtain or have the right to obtain  any  shares in  General  Partner,
shall not be  entitled to inspect the books or records of Newco LP and shall not
have any rights of a Limited  Partner under the Delaware Act, this  Agreement or
the Newco LP Agreement.

     (c) A transferor  of interests  shall remain a Limited  Partner of Newco LP
with respect to such  transferred  interests  until such time,  if ever,  as the
transferee  of such  interests is admitted as a substituted  Limited  Partner in
accordance with this Agreement.

     Section 8.4 Admission of Additional Limited Partners.  A Person (other than
a current Limited Partner) who purchases from Newco LP interests issued pursuant
to Section 8.1 shall be admitted to Newco LP as an  Additional  Limited  Partner
upon furnishing to Newco LP (a) a subscription  agreement,  in form satisfactory
to the General  Partner,  which  agreement  shall  include an acceptance by such
Person of all the terms and  conditions  of this  Agreement,  and (b) such other
documents as the General  Partner deems  necessary or advisable.  Such admission
shall become effective on the date that the General Partner determines that such
conditions have been satisfied. Additionally, any Note Investor who converts its
Convertible Notes into Limited Partnership  Interests shall be admitted to Newco
LP as an  Additional  Limited  Partner  (to the extent  that such  holder is not
already  a  Limited  Partner)  on the  terms  and  conditions  set forth in such
Convertible Notes and this Agreement. Additionally, any Second Closing Investors
who  purchase  Limited  Partnership  Interests  at the Second  Closing  shall be
admitted  to  Newco  LP as an  Additional  Limited  Partner  on  the  terms  and
conditions set forth in the October Investment Agreement.

     Section 8.5 Corporate Conversion; Drag Along Rights.
                 ---------------------------------------

     (a) At any time prior to the Second  Closing,  upon the  consent of Motient
Sub, TMI Sub and Class A Limited  Partners  holding a majority of the Percentage
Interests held by all Class A Limited Partners, and at any time after the Second
Closing, at the General Partner's  discretion,  Newco LP shall be converted into
corporate form ("Newco") by merger, statutory conversion or any other method set
forth in such consent (the "Corporate Conversion").  If the Corporate Conversion
is in  connection  with  an  initial  public  offering  of  Newco  LP's  (or its
successor's)  securities,  the  outstanding  interests  in  Newco  LP  shall  be
converted into common stock of Newco in accordance with the Percentage Interests
represented  by such  Limited  Partnership  Interests,  and each  holder of such
interests  shall take such steps as may be  reasonably  requested by the General
Partner in connection  therewith,  whereupon the rights and  obligations  of the
Limited Partners hereunder,  including,  without limitation, those arising under
Article 6, shall  cease and have no further  force and  effect.  If a  Corporate
Conversion is approved for any purpose other than in connection  with an initial
public  offering  of  Newco  LP's  (or  its  successor's)  securities,  (i)  the
respective  outstanding interests of Newco LP shall be converted into securities
of Newco which track, as closely as practicable,  the economic, voting and other
rights  represented  by such  outstanding  interests  immediately  prior  to the
Corporate  Conversion and (ii) the holders of such interests  shall enter into a
shareholders   agreement  and  such  other  agreements  and  the  organizational
documents of Newco will contain such  provisions as may be  necessary,  to allow
Newco to mimic,  as closely as  practicable,  the governance and other operating
provisions  of  the  Newco  LP  Agreement,  including,  without  limitation,  an
agreement by all  shareholders  holding stock with special  voting,  economic or
other rights to convert such stock into common  stock  immediately  prior to the
initial  public  offering  of  Newco  securities  on a  basis  similar  to  that
contemplated  by the  second  sentence  of this  Section  8.5(a).  To the extent
permitted by applicable law (including without limitation, Section 17-219 of the
Delaware Act), the consents of Limited Partners,  required by the first sentence
of this Section 8.5(a) shall be the only consents of Limited Partners  necessary
for  Newco LP to  effect a  Corporate  Conversion  and no other  class  votes or
consents  of Limited  Partners  or the  General  Partner  shall be  required  in
connection therewith.

     (b) At any  time  after  the  Second  Closing,  if  the  Required  Majority
determines  to  transfer  or  exchange  (in a merger,  business  combination  or
otherwise)  in one or a series of related  bona fide  arm's-length  transactions
(collectively,  the "Drag-Along  Transaction")  to an unrelated and unaffiliated
third  party  all of the  Limited  Partnership  Interests  held by such  Limited
Partners,  then,  upon thirty  (30) days'  written  notice to the other  Limited
Partners and Newco LP (the  "Drag-Along  Notice"),  which  notice shall  include
reasonable details of the proposed  transaction,  including the consideration to
be received by the Limited  Partners,  each other Limited  Partner and holder of
Limited  Partnership  Interests shall be obligated to, and shall sell,  transfer
and  deliver,  or cause to be sold,  transferred  and  delivered,  to such third
party, all of its Limited  Partnership  Interests in the same transaction at the
closing  thereof (and will deliver such Limited  Partnership  Interests free and
clear of all liens,  claims, or encumbrances  except this Agreement or the Newco
LP Agreement) (or shall vote in favor of or consent to any transaction requiring
the vote or consent of Limited Partners),  and shall otherwise  cooperate in the
consummation  of  such  transaction,  and  the  consideration  to be paid to the
Limited Partners shall be deemed to be Capital Proceeds and shall be distributed
to the Limited Partners  pursuant to Section 8.6 of the Newco LP Agreement as if
such transaction were a Capital Event. In the event a Drag Along  Transaction is
initiated  by the  Investors,  unless the  consideration  to be  received by the
Limited Partners is based solely on the respective  Percentage Interests held by
such  Limited  Partners,  (i) until the  second  anniversary  of the date of the
Second Closing,  the consent of the Limited  Partners  holding a majority of the
Common  Units shall be required  with respect to any Drag Along  Transaction  in
which the value of the aggregate  consideration  to be paid to the Investors for
their  Limited  Partnership  Interests is less than an amount equal to twice the
sum of such Investors' aggregate Capital Contributions and (ii) after the second
anniversary  date of the  Second  Closing,  each of  Motient  and TMI shall have
thirty (30) days from receipt of the Drag Along Notice to make, or cause a third
party to make, a bona fide offer that is no less  favorable to the Investors and
the other Limited Partners than the terms,  conditions and  consideration of the
Drag Along  Transaction  described  in such Drag Along  Notice and which will be
consummated within thirty (30) days after such offer is made.

     Section 9. Legends.  Each Stockholder consents to General Partner inserting
appropriate  legends  referencing the restrictions and obligations  contained in
this  Agreement  on  the  certificates  representing  the  Shares  held  by  the
Stockholders on or after the date of this Agreement.

     Section  10.   Stockholders'   Representation.   Each  Stockholder   hereby
                    -------------------------------
represents that, notwithstanding anything herein to the contrary, it has no plan
or intention to consummate any Transfer of Shares.

     Section 11. Miscellaneous.
     --------------------------

     (a) Representation. No Stockholder is a party to any other agreement, other
than the Newco LP Agreement and the October Investment  Agreement,  with respect
to the transfer or disposition of voting rights with respect to any Shares.

     (b)  Severability.  Should  any  one or  more  of the  provisions  of  this
Agreement be determined to be illegal or unenforceable,  each other provision of
this Agreement shall be given effect separately from the provision or provisions
determined to be illegal or unenforceable and shall not be affected thereby.

     (c) No Waiver.  No failure or delay on the part of any party in  exercising
any right,  power or remedy  hereunder  shall operate as a waiver  thereof;  nor
shall any single or partial exercise of any such right, power or remedy preclude
any other or further exercise thereof or the exercise of any other right,  power
or remedy hereunder.

     (d) Entire Agreement.  This Agreement, the October Investment Agreement and
the Newco LP Agreement, together with the exhibits thereto constitute the entire
agreement  among  the  parties  pertaining  to the  subject  matter  hereof  and
supersede all prior agreements and  understandings  of the parties in connection
herewith.

     (e) Amendment and Modification. This Agreement may be amended, modified and
supplemented  only by written  agreement  of the  holders  of a majority  of the
Shares (or, in the event the provision to be amended contains language requiring
the consent of a greater  percentage  of the Shares,  such greater  percentage);
provided,  however,  that any  amendment,  modification  or  supplement  to this
Agreement that would adversely  affect any individual  Stockholder,  or group of
Stockholders, in a manner different than its effect on other Stockholders, shall
require the prior written consent of such  Stockholder(s).  Notwithstanding  the
foregoing,  if Newco LP shall admit any new limited partner (other than upon the
conversion  of any  Convertible  Notes) and the Board shall  determine  that the
Board  should be expanded to allow for  representation  on the Board by such new
limited partner,  this Agreement may be amended by the written  agreement of the
holders  of a  majority  of the  Shares to  provide  for one or more  additional
directors   (the  number  of  such   additional   directors  to  be   reasonably
proportionate  to the  Percentage  Interest in Newco LP held by such new limited
partner  (after giving effect to the  conversion of the  Convertible  Notes then
outstanding)),  which  director(s)  shall  be  designated  by such  new  limited
partner.  Additionally,  any Second Closing Investors who purchase Shares at the
Second Closing shall be added by General  Partner as a Party hereto on the terms
and conditions set forth in the October Investment Agreement.

     (f) Remedies.  The Parties  acknowledge and agree that the breach of any of
the terms of this Agreement will cause irreparable  injury for which an adequate
remedy at law is not available. Accordingly, it is agreed that each party hereto
shall be entitled to an injunction,  restraining order or other equitable relief
to prevent breaches of this Agreement and to enforce  specifically the terms and
provisions hereof in any court of competent jurisdiction in the United States or
any state  thereof,  without the  requirement  of the posting of any bond.  Such
remedies shall be cumulative and  non-exclusive  and shall be in addition to any
other rights and remedies the Parties may have under this Agreement.

     (g)  Notices.  All  notices  provided  for in this  Agreement  shall  be in
writing,  duly signed by the party  giving such  notice,  and shall be delivered
personally,  sent by a nationally  recognized  overnight courier,  telecopied or
mailed by registered or certified mail, as follows:

          (i) If given to General Partner,  at General Partner's mailing address
          set forth below:

                  Mobile Satellite Ventures GP Inc.
                  10802 Parkridge Boulevard
                  Reston, Virginia 20191-5416
                  Fax:  (703) 758-6134
                  Attention:  President

                  with a copy to each  Stockholder as set forth in clause (ii)
                  below.

          (ii) If given to any Stockholder, at the address set forth on Schedule
          I hereof  (or as  modified  from  time to time by a  Stockholder  upon
          written notice to General Partner).

          Notices  delivered  personally  to an  addressee  or sent by overnight
     courier shall be deemed to have been given upon such delivery. Notices sent
     by  telecopier  shall be deemed to have been  given  upon  confirmation  by
     telecopy  answerback  (provided  that the  sending  of any such  notice  is
     followed  promptly by the mailing of the original of such notice).  Notices
     mailed by registered  or certified  mail shall be deemed to have been given
     upon the  expiration  of five (5) Business  Days after such notice has been
     deposited in the mail.

     (h)  Governing  Law;  Consent  to  Jurisdiction.  This  Agreement  shall be
governed by and construed in  accordance  with the laws of the State of Delaware
without  regard to any  applicable  principles  of conflicts of law.  Each party
agrees  that,  in  connection  with any legal suit or  proceeding  arising  with
respect to this Agreement, it shall submit to the non-exclusive  jurisdiction of
the United States  District  Court for the Southern  District of New York or the
applicable  New York state court  located in New York County and agrees to venue
in such courts.

     (i)  Counterparts.  This  Agreement  may  be  executed  in  any  number  of
counterparts,  each of which shall be deemed an original  but all of which shall
constitute one and the same instrument.

<PAGE>

     IN WITNESS  WHEREOF,  the parties hereto have executed this Agreement as of
the day and year first written above.

                               GENERAL PARTNER:

                               MOBILE SATELLITE VENTURES GP INC.

                               By:__________________________
                                  Name:
                                  Title:

                               STOCKHOLDERS:

                               [MOTIENT SUB]

                               By:__________________________
                                  Name:
                                  Title:

                               [TMI SUB]

                               By:__________________________
                                  Name:
                                  Title:

                               INVESTORS:
                               ---------

                               EXISTING INVESTORS:
                               ------------------

                               TELCOM SATELLITE VENTURES INC.

                               By:__________________________
                                  Name:
                                  Title:

                               NOTE INVESTORS:
                               --------------

                               TELCOM SATELLITE VENTURES II INC.

                               By:__________________________
                                  Name:
                                  Title:

                               EXISTING INVESTORS:
                               ------------------

                               COLUMBIA SPACE (QP), INC.

                               By:__________________________
                                  Name:
                                  Title:

                               COLUMBIA SPACE (AI), INC.

                               By:__________________________
                                  Name:
                                  Title:

                               COLUMBIA SPACE PARTNERS, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               NOTE INVESTORS:
                               --------------

                               COLUMBIA SPACE (QP) II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               COLUMBIA SPACE (AI) II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               COLUMBIA SPACE PARTNERS II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               EXISTING INVESTORS:
                               ------------------

                               SPECTRUM SPACE EQUITY
                               INVESTORS IV, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               SPECTRUM SPACE IV PARALLEL, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               SPECTRUM SPACE IV MANAGERS, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               NOTE INVESTORS:
                               --------------

                               SPECTRUM SPACE EQUITY INVESTORS IV-II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               SPECTRUM SPACE IV PARALLEL II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               SPECTRUM SPACE IV MANAGERS II, INC.

                               By:__________________________
                                  Name:
                                  Title:

                               MSV INVESTORS LLC

                               By:__________________________
                                  Name:
                                  Title:

<PAGE>

                                   SCHEDULE I

                                  STOCKHOLDERS
<TABLE>
<CAPTION>

------------------------------ --------------------------------------------------- ------------------------------
            Name                                    Address                              Number of Shares
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

<S>                            <C>                                                 <C>
Motient Sub                    10802 Parkridge Boulevard                           8,387,804.87
                               Reston, Virginia 20191-5416
                               Tel:  (703) 758-6130
                               Fax:  (703) 758-6134
                               Attention:  David Engvall, Vice President and
                               General Counsel,

                               with a copy to:
                               Hogan & Hartson L.L.P.
                               8300 Greensboro Drive
                               Suite 1100
                               McLean, Virginia  22102
                               Tel:  (703) 610-6123
                               Fax:  (703) 610-6200
                               Attention:  Richard K.A. Becker, Esq.
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Telcom Satellite Ventures      211 North Union Street                              720,000
Inc.                           Suite 300
                               Alexandria, Virginia 22314
                               Attention:  Hal B. Perkins
                               Tel:    (703) 706-3800
                               Fax:    (703) 706-3801
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Telcom Satellite Ventures II   211 North Union Street                              139,609.75
Inc.                           Suite 300
                               Alexandria, Virginia 22314
                               Attention:  Hal B. Perkins
                               Tel:    (703) 706-3800
                               Fax:    (703) 706-3801
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space (QP), Inc.      211 North Union Street                              345,042.42
                               Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:    (703) 519-3000
                               Fax:    (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space (AI), Inc.      211 North Union Street                              19,061.12
                               Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:    (703) 519-3000
                               Fax:   (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:    (617) 951-2233
                               Fax:   (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space Partners, Inc.  211 North Union Street                              275,896.46
                               Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:  (703) 519-3000
                               Fax:  (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space (QP) II, Inc.   211 North Union Street                              66,904.57
                               Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:  (703) 519-3000
                               Fax:  (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space (AI) II, Inc.   211 North Union Street                              3,696.00
                               Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:  (703) 519-3000
                               Fax:  (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Columbia Space Partners II,    211 North Union Street                              53,496.99
Inc.                           Suite 300
                               Alexandria, Virginia 22314
                               Attention:  James Fleming
                               Tel:  (703) 519-3000
                               Fax:  (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------
                               One International Place
Spectrum Space Equity          29th Floor                                          618,048.00
Investors IV, Inc.             Boston, MA 82110
                               Attention:  Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:   (617) 951-2233 Fax:  (888)
                               325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Spectrum Space IV Parallel,    One International Place                             14,464.00
Inc.                           29th Floor
                               Boston, MA 82110
                               Attention:  Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Spectrum Space IV Managers,    One International Place                             7,488.00
Inc.                           29th Floor
                               Boston, MA 82110
                               Attention: Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------
                               One International Place
Spectrum Space Equity          29th Floor                                          119,841.01
Investors IV-II, Inc.          Boston, MA 82110
                               Attention:  Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:   (617) 951-2233 Fax:  (888)
                               325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Spectrum Space IV Parallel     One International Place                             2,804.60
II, Inc.                       29th Floor
                               Boston, MA 82110
                               Attention:  Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------

Spectrum Space IV Managers     One International Place                             1,451.94
II, Inc.                       29th Floor
                               Boston, MA 82110
                               Attention: Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------
                                                                                   6,636,481.51
TMI Sub                        1601 Telesat Court
                               Gloucester Court
                               Canada K1B 1B9
                               Attn:  Rory McCormick

                               with a copy to:
                               Salans Hertzfeld Heilbronn Christy & Viener
                               Rockefeller Center
                               620 Fifth Avenue
                               New York, NY  10020-2457
                               Attn:  Owen D. Kurtin, Esq.
                               Tel:  (212) 623-8374
                               Fax: (212) 632-5555

------------------------------ --------------------------------------------------- ------------------------------
------------------------------ --------------------------------------------------- ------------------------------
                               c/o Rare Medium Group, Inc.
MSV Investors LLC              28 West 23rd Street                                 7,756,097.42
                               New York, New York 10010
                               Attention:  General Counsel
                               Tel:    (646) 638-9600
                               Fax:    (646) 638-9716

                               with a copy to:

                               Skadden, Arps, Slate, Meagher & Flom LLP
                               Four Times Square
                               New York, New York 10036
                               Attn:  Gregory A. Fernicola, Esq.
                               Tel:   (212) 735-3000
                               Fax:   (212) 735-2000

------------------------------ --------------------------------------------------- ------------------------------
</TABLE>EXHIBIT 10.57

                                    Exhibit D
                         to October Investment Agreement

                                    FORM OF

                          LIMITED PARTNERSHIP AGREEMENT

                                       OF

                          MOBILE SATELLITE VENTURES LP

     THIS LIMITED  PARTNERSHIP  AGREEMENT OF MOBILE  SATELLITE  VENTURES LP (the
"Partnership")  dated as of  [________  __,] 2001 is  entered  into by and among
Mobile Satellite  Ventures GP Inc., a Delaware  corporation,  as General Partner
("General  Partner"),  the Converting  Limited Partners,  [Motient Sub] and [TMI
Sub] (each  individually,  a "Limited Partner," and collectively,  together with
any  Additional  Limited  Partners  hereafter  admitted  to the  Partnership  in
accordance  with this  Agreement,  the "Limited  Partners" and together with the
General Partner, the "Partners.").

     WHEREAS,  Motient, as sole member,  formed a limited liability company (the
"LLC")  pursuant to the Delaware  Limited  Liability  Company Act (6 Del. C. ss.
18-101, et seq., the "LLC Act") by filing a Certificate of Formation on June 16,
2000  with the  Secretary  of State of  Delaware  and  entering  into a  limited
liability company operating agreement dated as of June 16, 2000; and

     WHEREAS,  the Converting  Limited  Partners were admitted as members of the
LLC on June 29,  2000 and the  Operating  Agreement  of the LLC was  amended and
restated  effective as of June 29, 2000 by a certain  First Amended and Restated
Limited Liability Company Agreement (the "LLC Agreement"); and

     WHEREAS,  the  members  of the LLC and the  General  Partner  approved  the
conversion of the LLC to a Delaware  Limited  Partnership in accordance with the
terms and  conditions  set forth in the LLC  Agreement  and  pursuant to Section
18-216 of the LLC Act and Section  17-217 of the  Delaware  Act,  whereupon  the
members of the LLC and the other Persons listed as LIMITED  PARTNERS on Schedule
I hereto  became  Limited  Partners  of the  Partnership  and  Mobile  Satellite
Ventures GP, Inc. was admitted as General Partner of the Partnership; and

     WHEREAS,  the  Note  Investors  have  on  the  date  hereof  purchased  the
Convertible  Notes which are convertible  into limited partner  interests in the
Partnership pursuant to their terms; and

     WHEREAS,  the Note Investors shall be entitled to vote or take other action
on an as-converted  basis as provided in this Agreement on the same basis as the
Limited Partners; and

     WHEREAS,  the General Partner has executed,  delivered and filed (or caused
to be delivered and filed) the  Certificate of Conversion and the Certificate of
Limited Partnership pursuant to the terms of Section 17-204 of the Delaware Act;
and

     WHEREAS,  the  parties  hereto  desire to  continue  the  existence  of the
Partnership on the terms set forth in this Agreement and in accordance  with the
October Investment Agreement and the Ancillary Agreements;

     NOW,  THEREFORE,  in  consideration  of the agreements and  obligations set
forth  herein and for other good and  valuable  consideration,  the  receipt and
sufficiency  of which are hereby  acknowledged,  the  Partners  hereby  agree as
follows:

                                   ARTICLE I

                                  DEFINED TERMS

Section  1.1  Definitions.  Unless the  context  otherwise  requires,  the terms
defined in this Article I shall,  for the purposes of this  Agreement,  have the
meanings herein specified.

     "Additional  Limited Partner" means a Person admitted to the Partnership as
a Limited Partner pursuant to Section 8.4 of the Stockholders' Agreement.

     "Adjusted Capital Account" means, with respect to any Limited Partner,  the
balance in such Limited  Partner's  Capital  Account,  increased by such Limited
Partner's share of the Minimum Gain and "partner  nonrecourse debt minimum gain"
(as defined in Treasury Regulations Section 1.704-2(i)(2)).

     "Adjusted  Capital  Account  Deficit"  means,  with  respect to any Limited
Partner,  the deficit balance, if any, in such Limited Partner's Capital Account
as of the end of the relevant Fiscal Year,  after giving effect to the following
adjustments:

          (i) Credit to such  Capital  Account  any amounts  which such  Limited
     Partner is  obligated  to restore or is deemed to be  obligated  to restore
     pursuant  to the  penultimate  sentences  of  Treasury  Regulations  ss.ss.
     1.704-2(g)(1) and 1.704-2(i)(5); and

          (ii) Debit to such  Capital  Account the items  described  in Treasury
     Regulations ss. 1.704-1(b)(2)(ii)(d)(4), (5) and (6).

The foregoing  definition  of Adjusted  Capital  Account  Deficit is intended to
comply with the provisions of Treasury Regulations ss.  1.704-1(b)(2)(ii)(d) and
shall be interpreted consistently therewith.

     "Affiliate"  means with  respect to a  specified  Person,  any Person  that
directly or indirectly  controls,  is controlled  by, or is under common control
with, the specified Person. As used in this definition, the term "control" means
the  possession,  directly  or  indirectly,  of the power to direct or cause the
direction of the management and policies of a Person,  whether through ownership
of voting securities, by contract or otherwise.

     "Agreement" means this Limited Partnership Agreement of the Partnership, as
amended, modified, supplemented or restated from time to time.

     "Ancillary  Agreements" has the meaning set forth in the October Investment
Agreement.

     "Bankruptcy" means, with respect to any Person, such Person shall generally
not pay its debts as such  debts  become  due,  or shall  admit in  writing  its
inability to pay its debts generally, or shall make a general assignment for the
benefit of creditors,  or any proceeding  shall be instituted by or against such
Person seeking to adjudicate it a bankrupt or insolvent, or seeking liquidation,
winding up,  reorganization,  arrangement,  adjustment,  protection,  relief, or
composition of it or its debts under any law relating to bankruptcy,  insolvency
or  reorganization  or relief of  debtors,  or seeking the entry of an order for
relief or the  appointment  of a receiver,  trustee,  custodian or other similar
official for it or for any substantial  part of its property and, in the case of
any such  proceeding  instituted  against it (but not instituted by it),  either
such proceeding shall remain  undismissed or unstayed for a period of sixty (60)
days,  or any of the  actions  sought  in such  proceeding  (including,  without
limitation,  the entry of an order for relief  against,  or the appointment of a
receiver,  trustee,  custodian  or other  similar  official  for it,  or for any
substantial  part of its  property)  shall occur;  or such Person shall take any
action to authorize any of the actions set forth above.

     "Capital Account" means,  with respect to any Limited Partner,  the account
maintained for such Limited Partner in accordance with the provisions of Section
4.4 hereof.

     "Capital  Contribution"  means,  with respect to any Limited  Partner,  the
aggregate  of its  Initial  Capital  Contribution,  if any,  together  with  any
contributions  made to the  Partnership  pursuant  to Section 4.1 hereof by such
Limited  Partner  with  respect  to  the  Limited  Partnership  Interest  in the
Partnership now or hereafter held or purchased by such Limited Partner.

     "Capital Event" means (a) a sale, transfer,  or other disposition of all or
substantially  all the  assets of the  Partnership  or (b) any  dissolution  and
liquidation of the Partnership.

     "Capital  Proceeds"  means  the  proceeds  received  (or in the  case  of a
distribution  of the  Partnership  in kind deemed  received if the property were
sold for its Gross  Asset  Value) by the  Partnership  from a Capital  Event but
excluding  any  amounts  reasonably  determined  by the  General  Partner  to be
necessary to provide a reasonable reserve for working-capital needs or any other
contingencies of the Partnership.

     "Certificate  of  Conversion"  means the  Certificate  of Conversion of the
Partnership and any and all amendments  thereto and  restatements  thereof filed
with the office of the  Secretary of State of the State of Delaware  pursuant to
the Delaware Act.

     "Certificate  of  Limited  Partnership"  means the  Certificate  of Limited
Partnership  of  the  Partnership  and  any  and  all  amendments   thereto  and
restatements  thereof filed on behalf of the Partnership  with the office of the
Secretary of State of the State of Delaware pursuant to the Delaware Act.

     "Class A Limited Partners" means Limited Partners holding Class A Preferred
Units.

     "Class A Preferred Unit" means a unit of interest in the  Partnership  with
the rights and  privileges  specified  herein  for Class A  Preferred  Units and
representing a Percentage Interest equal to one divided by the number of Class A
Preferred Units and Common Units then held by all Limited Partners.

     "Code"  means the Internal  Revenue  Code of 1986,  as amended from time to
time, or any  corresponding  federal tax statute  enacted after the date of this
Agreement.  A reference to a specific  section (ss.) of the Code refers not only
to such specific section but also to any corresponding  provision of any federal
tax statute enacted after the date of this Agreement,  as such specific  section
or  corresponding  provision  is in  effect  on the date of  application  of the
provisions of this Agreement containing such reference.

     "Common Unit" means a unit of interest in the  partnership  with the rights
and privileges  specified  herein for Common Units and representing a Percentage
Interest  equal to one  divided  by the  number of Class A  Preferred  Units and
Common Units then held by all Limited Partners.

     "Control Party" means (i) an Affiliate that has direct or indirect majority
voting control of a Limited Partner, or (ii) an Affiliate that has a majority of
its voting  interests held,  directly or indirectly,  by a Limited Partner or by
Persons that have direct or indirect voting control of a Limited Partner.

     "Convertible  Notes" has the meaning  set forth in the  October  Investment
Agreement.

     "Converting  Limited Partner" means the Persons listed on Schedule I hereto
who  were  members  of the LLC  prior to the date  hereof  and who hold  Class A
Preferred Units as a result of the conversion of the LLC to the Partnership.

     "Covered  Person"  means any Limited  Partner,  any  Affiliate of a Limited
Partner or any officers,  directors,  representatives,  shareholders,  partners,
employees,  representatives  or agents of a Limited Partner or their  respective
Affiliates,  or any  directors,  officers,  shareholders,  partners,  employees,
representatives   or  agents  of  the  Partnership  or  its  Affiliates  or  any
liquidating trustee under Section 13.3.

     "Delaware Act" means the Delaware Revised Uniform Limited  Partnership Act,
6 Del. C.ss. 17-101, et seq., as amended from time to time.

     "Depreciation" means, for each Fiscal Year or other period, an amount equal
to the  depreciation,  amortization or other cost recovery  deduction  allowable
with  respect  to an asset  for such  Fiscal  Year or  other  period;  provided,
however,  that if the Gross Asset Value of an asset  differs  from its  adjusted
basis for federal  income tax  purposes at the  beginning of such Fiscal Year or
other period,  Depreciation shall be an amount that bears the same ratio to such
beginning Gross Asset Value as the federal income tax depreciation, amortization
or other cost recovery deduction with respect to such asset for such Fiscal Year
or other  period  bears to such  beginning  adjusted  tax  basis;  and  provided
further, that if the federal income tax depreciation, amortization or other cost
recovery  deduction  for such Fiscal Year or other period is zero,  Depreciation
shall be determined with reference to such beginning Gross Asset Value using any
reasonable method selected by the General Partner.

     "Fiscal  Year" means (i) the period  commencing  upon the  formation of the
Partnership  and ending on December 31, 2001,  (ii) any  subsequent  twelve (12)
month  period  commencing  on January 1 and ending on December  31, or (iii) any
portion of the period  described  in clause (ii) of this  sentence for which the
Partnership  is  required  to  allocate  Profits,  Losses  and  other  items  of
Partnership income, gain, loss or deduction pursuant to Article VII hereof.

     "General  Partner"  shall mean Mobile  Satellite  Ventures GP, Inc., or any
Person who or which, at the time of reference thereto,  has been admitted to the
Partnership  as a General  Partner of the  Partnership  as a successor to Mobile
Satellite  Ventures GP, Inc. or as an additional  General Partner.  "Gross Asset
Value" means, with respect to any asset, such asset's adjusted basis for federal
income tax purposes, except as follows:

          (i) the  initial  Gross  Asset  Value of any  asset  contributed  by a
     Limited Partner to the Partnership  shall be the gross fair market value of
     such  asset,  as  agreed to by the  contributing  Limited  Partner  and the
     General Partner;

          (ii) the Gross Asset Value of all Partnership assets shall be adjusted
     to equal their respective  gross fair market values,  as determined in good
     faith  by  the  General  Partner,  as  of  the  following  times:  (a)  the
     acquisition  of an  additional  interest in the  Partnership  by any new or
     existing  Limited  Partner  or  any  other  adjustment  in  the  Percentage
     Interests of the Limited Partners;  (b) the distribution by the Partnership
     to a Limited Partner of more than a de minimis amount of Partnership assets
     as consideration for such Limited Partner's Limited  Partnership  Interest;
     and (c) the liquidation of the  Partnership  within the meaning of Treasury
     Regulations ss. 1.704-1(b)(2)(ii)(g); and

          (iii) the Gross Asset Value of any  Partnership  asset  distributed to
     any Limited  Partner  shall be the gross fair market value of such asset on
     the date of distribution, as determined by the General Partner.

If the Gross Asset Value of an asset has been determined or adjusted pursuant to
clause (i) or (ii) above, such Gross Asset Value shall thereafter be adjusted by
the  Depreciation  taken into account with respect to such asset for purposes of
computing Profits and Losses.

     "Initial  Capital  Contribution"  means,  with  respect  to any  Converting
Limited Partner,  such Limited Partner's  Capital  Contribution to the LLC as of
June 29,  2000 and with  respect to any Note  Investor  means any portion of the
principal  amount of any  Convertible  Note  elected by the Note  Investor to be
converted pursuant to the terms of such Convertible Note.

     "Initial   Public   Offering"  means  the  closing  of  a  firm  commitment
underwritten  public  offering of equity  interests  in the  Partnership  or its
successor.

     "Investors"  means each Limited Partner listed on the signature page hereof
as an Investor,  each other Person admitted as an Investor after the date hereof
and,  subject  to  Section  8.2(i) of the  Stockholders'  Agreement,  any Person
acquiring all or part of the Limited Partnership Interest of an Investor that is
admitted as a Limited Partner as provided herein.

     "Limited  Partner"  has the meaning set forth in the opening  paragraph  of
this Agreement.

     "Limited  Partnership  Interest" means a Limited Partner's aggregate rights
in the  Partnership  in  accordance  with this  Agreement  and the Delaware Act,
including such Limited Partner's right to share in the Profits and Losses of the
Partnership and right to receive distributions of the Partnership's assets.

     "LLC" has the meaning set forth in the first "Whereas" clause.

     "LLC Agreement" has the meaning set forth in the second "Whereas" clause.

     "Minimum  Gain" has the meaning set forth in  Treasury  Regulations  ss.ss.
1.704-2(b)(2) and 1.704-2(d).

     "Motient" means Motient Corporation, a Delaware corporation.

     "Motient Sub" means __________,  a Delaware corporation,  a special-purpose
wholly  owned  subsidiary  of Motient,  which  holds the number of Common  Units
reflected on Schedule I.

     "Non-Qualifying  Capital  Event"  means  any  Capital  Event  other  than a
Qualifying Capital Event.

     "Note  Investors"  has the  meaning  set  forth in the  October  Investment
Agreement, but shall not include any person or entity who, at the relevant time,
is not the holder of a Convertible Note.

     "Notes" shall mean the MSI Note and the TMI Note, as such terms are defined
in the October Investment Agreement.

     "October Investment  Agreement" means the Investment  Agreement dated as of
October __, 2001 among the LLC,  Motient,  TMI, and the  Investors  and the Note
Investors, as amended, restated, supplemented or revised from time to time.

     "Partner"  shall mean General  Partner or Limited Partner or any Person who
or which, at the time of reference thereto, has been admitted to the Partnership
as the General  Partner or an  Additional  Limited  Partner of the  Partnership.
"Partners" shall refer to all Partners at the time of reference thereto.

     "Partnership"  means  Mobile  Satellite  Ventures  LP, a  Delaware  limited
Partnership and, when the context so requires, its predecessor, the LLC.

     "Percentage  Interest" means with respect to any Limited Partner, the ratio
(expressed as a percentage) of the Units  actually held by such Limited  Partner
as of the date of  determination  to the  aggregate  Units  actually held by all
Limited  Partners  on such  date,  and  shall  be  reflected  on  Schedule  I in
accordance  with Section 2.1(c).  For purposes of voting and providing  consents
under  this  Agreement  and  for  purposes  of  Section  8 of the  Stockholders'
Agreement, but not, for the avoidance of doubt, for purposes of distributions of
cash  or tax  and  other  economic  rights  under  this  Agreement,  "Percentage
Interests"  means,  with respect to each Limited Partner and each Note Investor,
the ratio  (expressed as a percentage) of the Units (on an  as-converted  basis)
held by such Limited  Partner or such Note  Investor,  as the case may be, as of
the date of  determination  to all Units (on an as-converted  basis) held by all
Limited Partners and all Note Investors.

     "Person"  means  any  individual,  corporation,   association,  partnership
(general or limited),  joint venture,  trust, estate, limited liability company,
or other legal entity or organization.

     "Profits" and "Losses"  means,  for each Fiscal Year an amount equal to the
Partnership's  taxable  income  or loss  for such  Fiscal  Year,  determined  in
accordance with ss. 703(a) of the Code (but including in taxable income or loss,
for this purpose,  all items of income,  gain, loss or deduction  required to be
stated  separately  pursuant to ss.  703(a)(1) of the Code),  with the following
adjustments:

          (i) any income of the  Partnership  exempt from federal income tax and
     not otherwise taken into account in computing Profits or Losses pursuant to
     this definition shall be added to such taxable income or loss;

          (ii) any expenditures of the Partnership described in ss. 705(a)(2)(B)
     of the Code (or treated as  expenditures  described in ss.  705(a)(2)(B) of
     the Code pursuant to Treasury Regulations ss. 1.704-1(b)(2)(iv)(i)) and not
     otherwise  taken into  account in computing  Profits or Losses  pursuant to
     this definition shall be subtracted from such taxable income or loss;

          (iii) in the event the Gross Asset Value of any  Partnership  asset is
     adjusted  in  accordance  with clause  (ii) or (iii) of the  definition  of
     "Gross Asset Value"  above,  the amount of such  adjustment  shall be taken
     into  account  as gain or loss  from  the  disposition  of such  asset  for
     purposes of computing Profits or Losses;

          (iv) gain or loss resulting  from any  disposition of any asset of the
     Partnership  with respect to which gain or loss is  recognized  for federal
     income tax purposes shall be computed by reference to the Gross Asset Value
     of the asset  disposed of,  notwithstanding  that the adjusted tax basis of
     such asset differs from its Gross Asset Value; and

          (v) in lieu of the depreciation,  amortization and other cost recovery
     deductions  taken into  account in computing  such taxable  income or loss,
     there  shall be taken into  account  Depreciation  for such  Fiscal Year or
     other period,  computed in accordance with the definition of "Depreciation"
     above.

Any items of income, gain, deduction and loss included within Profits and Losses
shall be determined in a manner  consistent  with Section 704(b) of the Code and
the Treasury Regulations thereunder.

     "Qualifying  Capital  Event"  means any Capital  Event  occurring  when the
Partnership  is not Solvent  (before  giving effect to such Capital Event or the
proceeds  thereof)  and  pursuant  to which the  Capital  Proceeds  would not be
sufficient to satisfy completely the distributions  required to be made pursuant
to Section 8.6(b)(ii) and (iii).

     "Required  Majority" means Limited  Partners and Note Investors  holding at
least a majority of the Percentage  Interests  held by the Limited  Partners and
Note Investors  entitled to vote on any matter as of the date of  determination.
For  purposes  of this  Agreement,  each  holder of  Convertible  Notes  will be
entitled  to vote on any matter put to a vote of Limited  Partners  pursuant  to
this Agreement on an as-converted basis as of the date of determination.

     "Second  Closing"  has the  meaning  set  forth in the  October  Investment
Agreement.

     "Solvent" means, with respect to any Person on a particular date, that such
Person is able to pay such Person's debts as they fall due.

     "Stockholders'  Agreement" means the  Stockholders'  Agreement by and among
General Partner, the Limited Partners and the Note Investors.

     "Subsequent  Capital  Contribution"  means,  with  respect  to any  Limited
Partner,  the aggregate  Capital  Contributions  of such Limited Partner made on
this date or hereafter.

     "Tax Matters Partner" has the meaning set forth in Section 11.1.

     "TMI" means TMI Communications and Company Limited  Partnership,  a limited
partnership  organized  under the laws of the Province of Quebec and  indirectly
wholly-owned by BCE Inc.

     "TMI  Sub"  means  ________,  a  Delaware  limited  partnership  which is a
special-purpose  wholly-owned  subsidiary  of TMI and which  holds the number of
Common Units reflected on Schedule I.

     "Treasury   Regulations"  means  the  income  tax  regulations,   including
temporary  regulations,  promulgated  under the Code, as such regulations may be
amended from time to time  (including  corresponding  provisions  of  succeeding
regulations).

     "Units" means Common Units and Class A Preferred Units.

     "Unreturned  Initial  Capital  Contribution"  means,  with  respect  to any
Limited Partner,  the excess,  if any, of such Limited Partner's Initial Capital
Contribution over the cumulative  distributions to such Limited Partner pursuant
to Section 8.6(b)(ii).

     "Unreturned  Subsequent Capital  Contributions"  means, with respect to any
Limited  Partner,  the excess,  if any,  of such  Limited  Partner's  Subsequent
Capital Contributions over the cumulative  distributions to such Limited Partner
pursuant to Section 8.6(b)(iii) hereof.

Section 1.2  Headings.  The  headings  and  subheadings  in this  Agreement  are
included for convenience and  identification  only and are in no way intended to
describe,  interpret,  define  or limit  the  scope,  extent  or  intent of this
Agreement or any provision hereof.

Section 1.3 Interpretation. Throughout this Agreement, nouns, pronouns and verbs
shall be construed as masculine, feminine, neuter, singular or plural, whichever
shall be applicable. All references herein to "Articles", "Sections" and clauses
shall refer to  corresponding  provisions of this  Agreement,  unless  otherwise
specified.

                                   ARTICLE II

                              CONTINUATION AND TERM

Section 2.1 Continuation.
            ------------

(a) At the time set forth in the  Certificate  of  Conversion,  the  Partnership
shall continue as a limited  partnership under and pursuant to the provisions of
the Delaware  Act, the members of the LLC shall become the Limited  Partners and
the Partners agree that the rights, duties and liabilities of the Partners shall
be as provided in the Delaware Act, except as otherwise provided herein.

(b) Mobile Satellite Ventures GP, Inc. is hereby admitted as the General Partner
of the  Partnership  and the  Limited  Partners  are hereby  admitted as Limited
Partners of the Partnership and the Limited  Partners shall be issued the number
and class of Units, and the Percentage  Interests  represented  thereby,  listed
opposite such Person's name on such Schedule I.

(c) The name and mailing address of each Limited  Partner,  the number and class
of Units issued to such Limited Partner,  the Percentage  Interests  represented
thereby,  and the amount  contributed to the capital of the  Partnership by such
Limited  Partner  shall be listed on  Schedule I attached  hereto.  The  General
Partner  shall  update  Schedule  I from time to time as  necessary  to  reflect
accurately the information  therein,  including updates to reflect new issuances
of Limited Partnership Interests or assignments and transfers of all or any part
of a Limited Partner's Limited Partnership Interest, in each case, in accordance
with this Agreement and the October Investment Agreement and indicating the name
and address of such new Limited  Partner,  transferee or assignee  along with an
accurate  description of the Limited Partnership  Interest so issued transferred
or assigned,  including whether such new Limited Partner, transferee or assignee
has been or will be admitted to the Partnership as a substituted Limited Partner
or an Additional Limited Partner,  as the case may be, and provide copies of the
same to the Partners. Any amendment or revision to Schedule I made in accordance
with this Agreement and the October Investment  Agreement shall not be deemed an
amendment to this Agreement. Any reference in this Agreement to Schedule I shall
be deemed to be a reference  to Schedule I as amended and in effect from time to
time.  Section  2.2 Name.  The name of the  limited  partnership  formed by this
Agreement and by the filing of the Certificate of Conversion and the Certificate
of Limited  Partnership is "Mobile  Satellite  Ventures LP." The business of the
Partnership  may be conducted upon compliance with all applicable laws under any
other name designated, from time to time, by the General Partner.

Section  2.3  Term.  The term of the  Partnership  commenced  on the date of the
filing of the certificate of formation of the LLC in the office of the Secretary
of  State of the  State of  Delaware  and  shall  continue  until  dissolved  in
accordance  with this Agreement,  or if sooner,  in accordance with the Delaware
Act.

Section 2.4 Registered Agent and Office. The Partnership's  registered agent and
office in Delaware shall be CT Corporation System, Wilmington,  Delaware, 19801.
At any time, the General Partner may designate  another  registered agent and/or
registered office,  provided such new designation shall not adversely affect any
Partner.

Section 2.5 Principal Place of Business.  The principal place of business of the
Partnership shall be at 10802 Parkridge  Boulevard,  Reston,  Virginia 20191. At
any time,  the  General  Partner may change the  location  of the  Partnership's
principal place of business.

Section 2.6  Qualification  in Other  Jurisdictions.  The General  Partner shall
cause the  Partnership  to be qualified,  formed or registered  under assumed or
fictitious  name  statutes  or  similar  laws in any  jurisdiction  in which the
Partnership  transacts  business  in  which  such  qualification,  formation  or
registration is required or desirable.

Section 2.7 Agreement. This Agreement completely amends, restates and supersedes
the LLC Agreement.

                                  ARTICLE III

                      PURPOSE AND POWERS OF THE PARTNERSHIP

Section 3.1 Purpose.  The  Partnership  is formed for the object and purpose of,
and the nature of the business to be conducted  and promoted by the  Partnership
is, engaging in any lawful act or activity in which limited  partnerships may be
engaged under the Delaware Act and engaging in any and all activities necessary,
convenient, desirable or incidental to the foregoing.

Section 3.2 Powers of the Partnership.  The Partnership shall have the power and
authority to take any and all actions necessary, appropriate, proper, advisable,
convenient or incidental to or for the  furtherance of the purposes set forth in
Section 3.1.

Section 3.3  Limitations on Partnership  Powers.  Notwithstanding  the foregoing
provisions  of  Section  3.2,  the  Partnership  shall  not do  business  in any
jurisdiction  that would jeopardize the limitation on liability  afforded to the
Limited  Partners under the Delaware Act or this Agreement in such  jurisdiction
or elsewhere.

                                   ARTICLE IV

                   CAPITAL CONTRIBUTIONS AND CAPITAL ACCOUNTS

Section 4.1 Capital Contributions.

(a) The General  Partner shall not be required to make any Capital  Contribution
to the capital of the  Partnership,  shall have no Capital Account and shall not
acquire a Percentage  Interest or any Units, but shall  nonetheless be obligated
to serve as the general partner of the Partnership pursuant to Section 17-401(a)
of the Delaware Act.

(b) The Initial Capital Contributions,  and the Subsequent Capital Contributions
made by the Limited Partners as of the date of this Agreement are each set forth
on  Schedule  I hereto.  At the Second  Closing,  the  Investors  shall make the
respective  Capital  Contributions  and receive the additional number of Class A
Preferred  Units described in Section 2.1 of the October  Investment  Agreement.
Capital  Contributions  shall  be paid in the  manner  provided  in the  October
Investment Agreement or subscription  agreement,  as the case may be. Subject to
Section 8.1 of the Stockholders' Agreement, the Partnership may admit Persons as
Limited  Partners  and issue Units and  Limited  Partnership  Interests  to such
Persons without obligating such Persons to make Capital Contributions.

(c) Following the funding of the Subsequent Capital  Contributions being made as
of the date of this Agreement  described in clause (b) above, no Limited Partner
shall  be  required  or  permitted  to  contribute  additional  capital  to  the
Partnership except (i) as contemplated by the October Investment Agreement,  and
(ii)  subject to the  pre-emptive  rights  and other  applicable  provisions  of
Section 8 of the  Stockholders'  Agreement  hereof,  a Limited  Partner shall be
permitted to make additional  Capital  Contributions  pursuant to a subscription
agreement approved by the General Partner and the Required Majority.

Section 4.2       Status of Capital Contributions.
                  -------------------------------

(a) Except as otherwise  provided in this  Agreement,  no Limited  Partner shall
demand  or  receive  a return  of its  Capital  Contribution  and no return of a
Limited  Partner's  Capital   Contribution  shall  be  made  hereunder  if  such
distribution would violate applicable state law. Under circumstances requiring a
return of any Capital  Contribution,  no Limited Partner shall have the right to
demand or  receive  property  other  than  cash,  except as may be  specifically
provided in this Agreement.

(b) No Limited  Partner  shall  receive  any  interest,  salary or drawing  with
respect to its  Capital  Contribution  or its  Capital  Account or for  services
rendered on behalf of the  Partnership or otherwise in its capacity as a Limited
Partner,  except as otherwise  specifically provided in this Agreement.  Nothing
herein shall  preclude  any Limited  Partner  from  serving the  Partnership  in
another  capacity,  including  as an  employee,  contractor  or  consultant,  or
otherwise dealing with the Partnership in its individual  capacity and receiving
compensation or consideration therefor.

(c) Except as otherwise provided herein or by applicable state law, the Partners
shall be liable only to make Capital  Contributions  as provided in Section 4.1,
and no Partner  shall be  required to lend any funds to the  Partnership  nor to
make any additional  Capital  Contributions.  No Partner shall have any personal
liability  for the  repayment of any Capital  Contribution  of any other Limited
Partner.

Section 4.3 Limited Partnership  Interest.  A Limited Partnership Interest shall
for all  purposes be  personal  property.  A Limited  Partner has no interest in
specific Partnership property.

Section 4.4       Capital Accounts.
                  ----------------

(a) An individual  Capital  Account shall be established and maintained for each
Limited Partner.

(b)  The  Capital  Account  of each  Limited  Partner  shall  be  maintained  in
accordance with the following provisions:

     (i) to such Limited  Partner's Capital Account there shall be credited such
     Limited Partner's Capital Contribution, such Limited Partner's distributive
     share of Profits  and items of gross  income and gain and the amount of any
     Partnership  liabilities  that are assumed by such Limited  Partner or that
     are secured by any Partnership assets distributed to such Limited Partner;

     (ii) to such Limited  Partner's  Capital Account there shall be debited the
     amount  of  cash  and the  Gross  Asset  Value  of any  Partnership  assets
     distributed  to such  Limited  Partner  pursuant to any  provision  of this
     Agreement, such Limited Partner's distributive share of Losses and items of
     gross  deduction and loss and the amount of any liabilities of such Limited
     Partner  that are  assumed by the  Partnership  or that are  secured by any
     property contributed by such Limited Partner to the Partnership; and

     (iii) in  determining  the amount of any  liability  for  purposes  of this
     Subsection 4.4(b), there shall be taken into account ss. 752(c) of the Code
     and  any  other  applicable   provisions  of  the  Code  and  the  Treasury
     Regulations.

                                   ARTICLE V

                                    PARTNERS

Section  5.1  Powers  of  Limited  Partners.  Except as  otherwise  specifically
provided by this  Agreement or required by the Delaware Act, or Sections 2.4 and
7 of the October Investment Agreement, no Person other than the General Partner,
including any Limited Partner acting in its capacity as such, (a) shall have any
right to "participate in the control of the business" of the Partnership as such
phrase is construed under Section  17-303(b) of the Delaware Act, (b) shall have
the  power to be an agent of the  Partnership  or (c) shall  take any  action or
exercise any right with respect to the  Partnership not permitted to be taken or
exercised by a Limited Partner  pursuant to this Agreement and Section 17-303 of
the Delaware Act. In no event shall any Person,  other than the General Partner,
have any right,  power or authority  (1) to transact any business in the name of
the Partnership, (2) to act for, or on behalf of, the Partnership or (3) to bind
the Partnership,  such powers being vested solely and exclusively in the General
Partner.

Section 5.2 No General  Partner  Liability.  The General  Partner  shall have no
personal liability for the repayment of the Capital Contributions of the Limited
Partners.

Section  5.3  Actions of the  Limited  Partners.  Any action of the  Partnership
requiring  the consent or approval of the Limited  Partners,  or any  percentage
thereof,  shall be taken by a consent  in  writing  signed by  Limited  Partners
holding not less than the  Percentage  Interests  necessary  to take such action
pursuant to this Agreement.

Section 5.4  Partition.  Each Limited  Partner waives any and all rights that it
may have to maintain an action for partition of the Partnership's property.

Section 5.5 Withdrawal.  A Limited Partner may not withdraw from the Partnership
prior to the dissolution  and winding up of the Partnership  except as set forth
in this  Agreement  or the  October  Investment  Agreement.  A  Limited  Partner
attempting  to resign in  violation of this  Agreement  shall not be entitled to
receive any distribution and shall not otherwise be entitled to receive the fair
value of its Limited Partnership Interest except as otherwise expressly provided
for in this  Agreement.  The  withdrawal  of any Limited  Partner for any reason
shall not result in the dissolution of the Partnership.

Section  5.6  Removal of the  General  Partner by Limited  Partners.  A Required
Majority  of the  Limited  Partners  may at any time  effect the  removal of the
General  Partner with or without cause by  delivering  to the General  Partner a
notice of removal,  such removal to become  effective as provided in such notice
of removal.

Section 5.7 Bankruptcy, Resignation,  Withdrawal, Etc. of General Partner. After
the  resignation,  withdrawal,  dissolution,  Bankruptcy  or  insolvency  of the
General  Partner  which  would  otherwise  result  in  the  dissolution  of  the
Partnership  by operation of law, the  Partnership  will be  dissolved,  unless,
within  ninety  (90)  days  after  the  date  of such  resignation,  withdrawal,
dissolution,  Bankruptcy, or insolvency,  the Required Majority agree in writing
to continue the business of the Partnership and to the appointment, effective as
of the date of withdrawal or removal, of one or more successor General Partners.

                                   ARTICLE VI

                                   MANAGEMENT

Section 6.1  Management by the General  Partner.  Except as otherwise  expressly
provided herein and subject to the restrictions  contained in Sections 5.1, 5.6.
5.7,  6.2 and 6.6  hereof,  management  of the  Partnership  and  control of its
business shall be vested solely in the General Partner. Except for situations in
which the approval of the Limited  Partners is required by this  Agreement,  the
October  Investment  Agreement or by non-waivable  provisions of applicable law,
the General  Partner shall have the  exclusive  right,  power and  discretion to
manage,  operate and  control the  Partnership,  to do all things  necessary  or
appropriate to carry on its business and purposes, including but not limited to,
the  right to incur  and  satisfy  obligations  relating  to the  formation  and
operation of the  Partnership,  and to exercise all rights and powers  conferred
upon the General  Partner by the Delaware Act, in each case subject to the terms
and conditions set forth in this Agreement.

The General  Partner shall have the power to delegate  authority to the officers
and such other employees,  agents and  representatives  of the Partnership as it
may from time to time deem  appropriate  and in accordance  with this Agreement.
Any  delegation  of authority by the General  Partner to take any action must be
approved by the General  Partner in the same manner as would be required for the
General Partner to take such action directly.

Unless  authorized  to do so by this  Agreement  or by the General  Partner,  no
attorney-in-fact,  employee,  Limited  Partner or other agent of the Partnership
shall have any power or authority to bind the  Partnership in any way, to pledge
its credit or to render it liable monetarily for any purpose.

Section 6.2       Restrictions.
                  ------------

(a)  Notwithstanding the grant of authority to the General Partner under Section
6.1 hereof,  without the prior written  consent of the Required  Majority of the
disinterested  Limited  Partners,  the General Partner shall not permit or cause
the  Partnership  to enter  into  transactions  with  its  Limited  Partners  or
Affiliates of its Limited Partners except as otherwise  permitted in the October
Investment Agreement, this Agreement or the Ancillary Agreements;  provided that
the  Partnership  shall be permitted  to enter into each of the other  Ancillary
Agreements,  the  execution,  delivery and  performance  of which by the General
Partner on behalf of the Partnership is hereby approved and consented to by each
of the Limited Partners.

(b) Any  vacancy  in the  position  of  General  Partner  shall be filled by the
affirmative written consent of the Required Majority.

Section 6.3 General  Partner's Time. The General Partner shall devote all of its
time to the affairs of the Partnership.

Section 6.4 No Liability;  Indemnity. Neither the General Partner nor any of its
officers,  directors,  employees  or  agents  shall be  liable,  responsible  or
accountable to the Partnership or any Partner for any act or omission  performed
or omitted  pursuant to the authority  granted to it hereunder or by law, or for
any claim, loss, cost, damage, liability, demand or expense (including,  without
limitation,  attorneys'  fees),  resulting from the  performance of their duties
hereunder in  accordance  with the  requirements  of this  Agreement;  provided,
however,  that any such Person shall be liable,  accountable and responsible for
their willful  misconduct.  The Partnership shall indemnify the General Partner,
its  officers,  directors,  employees and agents and hold them harmless from any
claim,  loss, cost, damage,  liability,  demand or expense  (including,  without
limitation, attorneys' fees and disbursements), incurred or sustained by them by
reason of any act performed by them, or any omission by them for or on behalf of
the  Partnership  and  in  furtherance  of its  interest,  consistent  with  the
requirements  of this  Agreement,  but this  indemnity  shall  not  require  the
Partners to make any Capital  Contribution  therefor;  provided,  however,  such
indemnity shall not extend to the willful misconduct of any such Person.

Section  6.5  Reliance  by Third  Parties.(a)  Third  parties  dealing  with the
Partnership  may rely  conclusively  upon the power and authority of the General
Partner to act as set forth  herein and shall not be required to inquire into or
ascertain the authority of the General Partner so to act.

Section 6.6 General Authority.(a) The General Partner shall, except as otherwise
provided in this Agreement,  have all the rights and powers and shall be subject
to all the  restrictions  and  liabilities  of a  general  partner  in a limited
partnership under the Delaware Act.

Section  6.7  Limited  Liability.(a)  Performance  of one or  more  of the  acts
described in Article V and this  Article VI with  respect to the Partners  shall
not in any way impose any personal liability on any Limited Partner.  No Partner
or, in the  appropriate  case,  former  Partner shall be liable for any debts or
obligations of the Partnership in excess of its Capital  Contributions  (subject
to the obligation of a Limited Partner of the Partnership under the Delaware Act
to repay any funds wrongfully  distributed to it). All undistributed cash, which
would  otherwise be distributed to the Limited  Partners,  shall be available to
creditors to satisfy the debts and obligations of the  Partnership  prior to the
time of actual distribution.

Section 6.8 Special Purpose Provision.  The General Partner,  and any additional
or substitute  General Partner of the Partnership,  may not be an individual and
shall at all times have as its sole purpose to act as the General Partner of the
Partnership,  and  shall be  engaged  in no  other  business  or have any  other
purpose.  Any General Partner of the  Partnership (a) shall have  organizational
documents which conform in all material respects to the organizational documents
of the initial General  Partner,  and (b) shall be owned by the Limited Partners
and the Note Investors pro rata in accordance  with their  Percentage  Interests
(on an as-converted basis) from time to time.

Section 6.9       Grant of Power of Attorney.
                  --------------------------

Each  Limited  Partner,  by its  execution  hereof,  hereby  irrevocably  makes,
constitutes   and  appoints   the  General   Partner  as  its  true  and  lawful
attorney-in-fact,  with power and  authority  in its name,  place and stead,  to
make, execute,  sign, acknowledge and file on behalf of such Limited Partner and
on behalf of the Partnership:

(a) Such  amendments to the  Certificate  of Limited  Partnership as the General
Partner  shall  reasonably  deem  necessary  or desirable  consistent  with this
Agreement;

(b) All papers which may be deemed necessary or desirable by the General Partner
to effect the termination of the  Partnership  after its dissolution as provided
in this Agreement;

(c) All such other  instruments,  documents and certificates which may from time
to time be required or permitted by the laws of any state,  the United States of
America,  or  any  political  subdivision  or  agency  thereof,  to  effectuate,
implement,  continue and defend the valid and subsisting  existence,  rights and
property of the Partnership as a limited  partnership and its power to carry out
its  purposes  as set  forth  in this  Agreement;  provided,  however,  that any
decisions other than  administrative  ones shall first have been approved by the
applicable approvals as provided herein.

Section 6.10      Terms of Grant.
                  --------------

The foregoing appointment in Section 6.9:

(a) Is  irrevocable  and shall be deemed to be a special  power  coupled with an
interest in  recognition  of the fact that the General  Partner  will be relying
upon such power of attorney to act as  contemplated  by this  Agreement  in such
execution,  acknowledgment  and  filing and such  other  actions by the  General
Partner on behalf of the Limited Partners and the Partnership;

(b) Shall survive the dissolution or Bankruptcy of any Limited Partner  granting
the same and the  transfer,  by  operation of law or  otherwise,  by any Limited
Partner of the whole or any part of its interest in and to the Partnership,  its
capital, Profits or Losses hereunder; and

(c) May be exercised by the General  Partner on behalf of any Limited Partner by
a facsimile  signature  of the General  Partner,  as  attorney-in-fact  for such
Limited Partner.

Section 6.11      Separate Form.

The foregoing  appointment is self operative but, in confirmation  thereof, each
Limited Partner hereby agrees to execute, acknowledge and deliver to the General
Partner,  promptly  upon  request  therefor by the General  Partner,  a power of
attorney in recordable form  satisfactory to the General Partner  evidencing the
foregoing appointment.

                                   ARTICLE VII

                                   ALLOCATIONS

Section 7.1       Profits and Losses.
                  ------------------

(a) Except as  otherwise  set forth in Section 7.2 hereof,  Profits,  Losses and
items of income,  gain,  deduction and loss of the  Partnership  for each Fiscal
Year shall be allocated among all Persons who were Limited  Partners during such
Fiscal Year in a manner that will,  as nearly as  possible,  cause the  Adjusted
Capital  Account  balance of each  Limited  Partner (as computed for purposes of
section  704(b) of the Code) at the end of such  Fiscal  Year to be equal to the
sum  of the  amounts  of  cash  or the  Gross  Asset  Value  of  other  property
distributable  to such Limited  Partner  pursuant to Article VIII hereof at such
time  assuming that all the remaining  assets of the  Partnership  were sold for
their Gross Asset Values,  all debts of the  Partnership  were paid according to
their terms (with any  nonrecourse  debt for U.S.  Federal  income tax  purposes
deemed paid in amounts  not in excess of the Gross  Asset Value of the  property
securing  such  nonrecourse  debt)  and the  cash  or  other  property  received
therefrom  was  distributed  to the  Limited  Partners  in  accordance  with the
priorities set forth in Article VIII hereof.

(b) Notwithstanding  Section 7.1(a), Losses allocated pursuant to Section 7.1(a)
to any Limited  Partner for any Fiscal Year shall not exceed the maximum  amount
of Losses that may be  allocated to such Limited  Partner  without  causing such
Limited  Partner to have an Adjusted  Capital Account Deficit at the end of such
Fiscal Year. Any Losses in excess of the limitation in this Section 7.1(b) shall
be specially  allocated  solely to the other Limited Partners in accordance with
the  priorities in Article VIII hereof to the maximum  extent  permitted by this
Section 7.1(b). In addition,  notwithstanding  Section 7.1(b),  Profits shall be
allocated to reverse any Losses  specially  allocated  pursuant to the preceding
sentence in inverse order to those special loss  allocations and then to reverse
any  Losses  allocated  under  Section  7.1(a) in  inverse  order to those  loss
allocations.

(c) An allocation of Profits or Losses to a Limited  Partner shall be treated as
an allocation to such Limited  Partner of the same share of each item of income,
gain, loss and deduction that is taken into account in computing such Profits or
Losses, as the case may be.

Section 7.2 Special Allocations. The following special allocations shall be made
in the following order:

(a)  Minimum  Gain  Chargeback.  If  there is a net  decrease  in  Minimum  Gain
(determined  as  provided  in  Treasury   Regulations   ss.ss.   1.704-2(d)  and
1.704-2(g)) during any Fiscal Year, certain items of income and gain,  including
gross income or gain,  shall be allocated to the Limited Partners in the amounts
and manner described in Treasury Regulations ss. 1.704-2(f). This Section 7.2(a)
is intended to comply with the minimum gain chargeback  requirement  relating to
partnership  non-recourse  liabilities  (as defined in Treasury  Regulations ss.
1.704-2(f)) and shall be so interpreted.

(b)  Partner  Non-recourse  Debt  Minimum  Gain  Chargeback.  If  there is a net
decrease in Minimum Gain  attributable to partner  non-recourse debt (determined
pursuant to Treasury Regulations ss. 1.704-2(i)) during any Fiscal Year, certain
items of income and gain,  including gross income or gain, shall be allocated as
quickly as possible to those Limited  Partners  which had a share of the Minimum
Gain  attributable  to the  partner  non-recourse  debt (such  share  determined
pursuant to Treasury  Regulations ss.  1.704-1(i)(5))  in the amounts and manner
described in Treasury Regulations ss. 1.704-2(i) and (j). This Section 7.2(b) is
intended to comply  with the minimum  gain  chargeback  requirement  relating to
partner non-recourse debt set forth in Treasury  Regulations ss.  1.704-2(i)(4))
and shall be so interpreted.

(c)  Allocation  of   Non-recourse   Deductions.   Deductions   attributable  to
obligations  with respect to which a Limited  Partner bears the economic risk of
loss  within the  meaning of  Treasury  Regulation  ss.  1.704-2(b)(4)  shall be
allocated to the Limited Partner or Limited Partners that bear the economic risk
of loss for such debt in accordance with the requirements of Treasury Regulation
ss. 1.704-2(i)(1). "Nonrecourse Deductions" (as such term is defined in Treasury
Regulations  ss.ss.  1.704-2(b)(1)  and 1.704-2(c)) of the Partnership  shall be
allocated to the Limited Partners in proportion to their Percentage Interests.

(d)  Qualified  Income  Offset.  In the event any Limited  Partner  unexpectedly
receives any  adjustments,  allocations or  distributions  described in Treasury
Regulations ss. 1.704-1(b)(2)(ii)(d)(4), (5) or (6), items of Partnership income
and gain  (consisting of a pro rata portion of each item of Partnership  income,
including gross income, and gain for such year) shall be specially  allocated to
such Limited  Partner in an amount and manner  sufficient to  eliminate,  to the
extent  required by the  Treasury  Regulations,  the  Adjusted  Capital  Account
Deficit  of such  Limited  Partner  as quickly  as  possible,  provided  that an
allocation  pursuant  to this  Section  7.2(d)  shall be made if and only to the
extent that such Limited Partner would have an Adjusted  Capital Account Deficit
after  all  other  allocations  provided  for in  this  Article  VII  have  been
tentatively made as if this Section 7.2(d) were not in the Agreement.

(e) Gross  Income  Allocation.  In the event any  Limited  Partner has a deficit
Capital  Account at the end of any  Fiscal  Year that is in excess of the sum of
(i) the amount such Limited  Partner is obligated to restore and (ii) the amount
such  Limited  Partner  is deemed to be  obligated  to restore  pursuant  to the
penultimate   sentences  of  Treasury   Regulations  ss.ss.   1.704-2(g)(1)  and
1.704-2(i)(5),  such  Limited  Partner  shall be  specially  allocated  items of
Partnership  income and gain  (consisting  of a pro rata portion of each item of
Partnership  income,  including  gross  income,  and gain for such  year) in the
amount of such  excess as  quickly  as  possible,  provided  that an  allocation
pursuant  to this  Section  7.2(e)  shall be made if and only to the extent that
such Limited  Partner would have a deficit Capital Account in excess of such sum
after  all  other  allocations  provided  for in  this  Article  VII  have  been
tentatively  made as if Section 7.2(d) above and this Section 7.2(e) were not in
the Agreement.

(f) Regulatory  Allocations.  The  allocations  set forth in Section  7.2(a)-(e)
hereof (the  "Regulatory  Allocations")  are  intended  to comply  with  certain
requirements  of the  Treasury  Regulations.  It is the  intent  of the  Limited
Partners  that, to the extent  possible,  all  Regulatory  Allocations  shall be
offset either with other Regulatory  Allocations or with special  allocations of
other items of  Partnership  income,  gain,  loss or deduction  pursuant to this
Section  7.2(f).  Therefore,  the  General  Partner  shall make such  offsetting
special allocations of Partnership income,  gain, loss and deduction in whatever
manner it determines appropriate, so that, after such offsetting allocations are
made, each Limited Partner's Capital Account balance is, to the extent possible,
equal to the Capital  Account  balance  such Limited  Partner  would have if the
Regulatory  Allocations were not part of the Agreement and all Partnership items
were  allocated  pursuant to Section  7.1. In  exercising  its  discretion,  the
General  Partner  shall  take into  account  how future  Regulatory  Allocations
pursuant to Sections  7.2(a) and (b) hereof  that,  although  not yet made,  are
likely to offset other  Regulatory  Allocations  previously  made under  Section
7.2(c) hereof.

(g) Section 754  Adjustment.  To the extent an  adjustment  to the  adjusted tax
basis of any  Partnership  asset pursuant to ss. 734(b) or 743(b) of the Code is
required, pursuant to Treasury Regulations ss. 1.704-1(b)(2)(iv)(m), to be taken
into account in determining  Capital Accounts,  the amount of such adjustment to
the  Capital  Accounts  shall be treated  as an item of gain (if the  adjustment
increases  the basis of the  asset) or loss (if the  adjustment  decreases  such
basis),  and such  gain or loss  shall be  specially  allocated  to the  Limited
Partners in a manner  consistent with the manner in which their Capital Accounts
are required to be adjusted pursuant to such regulation.

Section 7.3       Allocation Rules.
                  ----------------

(a) For purposes of determining the Profits, Losses or any other items allocable
to any period, Profits, Losses and any such other items shall be determined on a
daily,  monthly or other basis,  as determined by the General  Partner using any
method  that  is  permissible  under  ss.  706  of the  Code  and  the  Treasury
Regulations thereunder.

(b) Except as otherwise  provided in this  Agreement,  all items of  Partnership
income,  gain, loss,  deduction and any other allocations not otherwise provided
for shall be divided among the Limited  Partners in the same proportions as they
share Profits and Losses for the Fiscal Year in question.

(c) The  Limited  Partners  are  aware of the  income  tax  consequences  of the
allocations  made by this  Article  VII and  hereby  agree  to be  bound  by the
provisions of this Article VII in reporting  their shares of Partnership  income
and loss for income tax purposes.

Section 7.4       Section 704(c) of the Code.
                  --------------------------

(a) In  accordance  with ss.  704(c)  of the Code and the  Treasury  Regulations
thereunder,  income,  gain,  loss and  deduction  with  respect to any  property
contributed  to the  capital  of the  Partnership  shall,  solely for income tax
purposes,  be allocated among the Limited  Partners so as to take account of any
variation  between the adjusted  basis of such property to the  Partnership  for
federal income tax purposes and its initial Gross Asset Value.

(b) In the event the Gross  Asset  Value of any  Partnership  asset is  adjusted
pursuant to the  definition  of "Gross  Asset  Value"  contained  in Section 1.1
hereof,  subsequent allocations of income, gain, loss and deduction with respect
to such asset shall take account of any variation  between the adjusted basis of
such asset for federal income tax purposes and its Gross Asset Value in the same
manner as under ss. 704(c) of the Code and the Treasury Regulations thereunder.

(c) Allocations  pursuant to this Section 7.4 shall be calculated by the General
Partner  using the remedial  method  under Code Section  704(c) and the Treasury
Regulations  promulgated  thereunder  and are solely for  purposes  of  federal,
state, and local taxes and shall not affect, or in any way be taken into account
in computing, any Limited Partner's Capital Account or share of Profits, Losses,
other items, or distributions pursuant to any other provision of this Agreement.

Section 7.5 Uncertainties in Allocations and  Distributions.  In the event there
is an ambiguity  regarding the  application  of this Section 7 or Section 8 to a
particular  transaction,  the income and expense from such transaction  shall be
allocated among the Limited  Partners,  and  distributions of cash in respect of
such transaction shall be made, in such proportions that the General Partner, in
its reasonable discretion, deems equitable, practicable and consistent with this
Agreement,  the regulations  under the Code and other applicable law;  provided,
however,  that no such  allocation or  distribution by the General Partner shall
discriminate against any Limited Partner.

                                  ARTICLE VIII

                                  DISTRIBUTIONS

Section 8.1  Distributions(a)  . Except as  otherwise  provided in Section  8.2,
Section 8.6 and Section 13.3 below, the Partnership shall make  distributions of
cash to the  Limited  Partners  in  proportion  to their  respective  Percentage
Interests at such time or times and in such  amounts as the General  Partner may
determine in its sole discretion.

Section 8.2 Distributions to Pay Taxes.  Prior to March 15 of the next following
Fiscal Year,  the General  Partner shall  distribute to the Limited  Partners an
amount sufficient for the Limited Partners out of cash available therefor to pay
their tax  liabilities  which arise in respect of their shares of cumulative net
taxable income and gain of the Partnership  for such Fiscal Year,  determined as
set forth below by the General Partner, prior to the making of any distributions
pursuant to Sections 8.1 and 8.6 hereof. Any funds distributed  pursuant to this
Section  8.2 shall  reduce the amount  that a Limited  Partner  would  otherwise
receive  pursuant to Sections 8.1 and 8.6. For purposes of this Section 8.2, the
amount of tax distributions  made to a Limited Partner for any Fiscal Year shall
be equal to the excess, if any, of (i) the product of (A) the excess, if any, of
(I) its  cumulative  share of net taxable  income or gain for the current Fiscal
Year and all prior  Fiscal Years over (II) its  cumulative  share of net taxable
loss and  deduction  for all prior  Fiscal  Years and (B) the sum of the highest
rate of Canadian  or United  States  federal,  state,  provincial  and local tax
imposed on any Limited  Partner  calculated,  with respect to a Limited  Partner
that is a  pass-through  entity (for  Canadian or United  States tax  purposes),
based on the type of taxpayer which the  beneficial  owners of interests in such
pass-through  entity  are for  such  year  with  respect  to  items  of the same
character as such net income and gain,  taking into account the deductibility or
creditability  of federal,  state,  provincial  and local taxes for  Canadian or
United  States  federal  income  tax  purposes  and  based  on  such  reasonable
assumptions  as the General  Partner  determines in good faith to be appropriate
(such  assumptions not to include the effect of any net operating  losses or any
other similar tax benefits available to a Limited Partner), over (ii) the amount
of any  distributions  made to such Limited Partner pursuant to this Section 8.2
in a prior Fiscal Year.

Section 8.3 Dissolution. Upon the dissolution and winding up of the Partnership,
the assets of the  Partnership  shall be distributed to the Limited  Partners as
provided in Section 13.3 below.

Section 8.4 Withholding  Taxes. All amounts withheld pursuant to the Code or any
provision  of any state,  local or foreign tax law with  respect to any payment,
distribution  or allocation to the Limited  Partners shall be treated as amounts
distributed  to the  Limited  Partners  pursuant  to this  Article  VIII for all
purposes of this  Agreement.  The  Partnership  is  authorized  to withhold from
distributions and to pay over to any federal, state, local or foreign government
any amounts required to be so withheld  pursuant to the Code or any provision of
any other federal,  state,  local or foreign law and shall allocate such amounts
to those Limited Partners with respect to which such amounts were withheld. Each
Limited Partner shall indemnify the Partnership and each of the Partners against
any losses  (including,  without  limitation,  any tax  penalties  and interest)
incurred by reason of any failure by the Partnership to make adequate  deduction
or withholding from any distribution made to such Partner.

Section 8.5 Limitations on  Distribution.  Notwithstanding  any provision to the
contrary  contained  in  this  Agreement,  the  Partnership  shall  not  make  a
distribution to the Limited Partners if such distribution in the aggregate would
violate Section 17-607 of the Delaware Act or other applicable law.

Section 8.6  Capital  Proceeds.  Following  the  receipt by the  Partnership  of
Capital Proceeds, a portion of such Capital Proceeds sufficient for each Limited
Partner to pay its tax  liabilities  which arise in respect of the Capital Event
giving rise to such  Capital  Proceeds,  determined  as set forth in Section 8.2
above,  shall be  distributed  to the Limited  Partners  pursuant to Section 8.2
above.  If the General  Partner,  in its sole  discretion,  determines  that the
Partnership  shall  distribute  any  remaining  Capital  Proceeds,  such Capital
Proceeds shall be distributed among the Limited Partners as follows:

(a) First,  to pay the creditors of the  Partnership,  including all outstanding
amounts then due under the Notes and the  Convertible  Notes in accordance  with
the terms  thereof;  Second,  to the  Limited  Partners in a manner to cause the
cumulative prior and current Capital Proceeds distributed to each of the Limited
Partners  to be in  the  same  relative  proportions  as the  Limited  Partners'
respective Percentage Interests;  provided, however, that Capital Proceeds shall
be distributed in accordance  with this Section 8.6(a) only if it results in the
receipt by the Class A Limited  Partners of cumulative  distributions of Capital
Proceeds  in an  amount  at least  equal to twice the sum of the Class A Limited
Partners' aggregate Capital Contributions;

(b) Upon a Qualifying  Capital Event, the Capital Proceeds  resulting  therefrom
shall be distributed as follows:

     (i)  First,  to  pay  the  creditors  of  the  Partnership,  including  all
     outstanding  amounts then due under the Notes and the Convertible  Notes in
     accordance with the terms thereof;

     (ii) Second,  to the Class A Limited  Partners in  proportion to and to the
     extent of each such Class A Limited  Partners'  Unreturned  Initial Capital
     Contributions; and

     (iii) Third, to the Limited  Partners in proportion to and to the extent of
     their Unreturned Subsequent Capital Contributions.

(c) In the event of a  Non-Qualifying  Capital  Event to which  clause (a) above
does not apply, the Capital Proceeds resulting therefrom shall be distributed as
follows:

     (i)  First  to  pay  the  creditors  of  the  Partnership,   including  all
     outstanding  amounts then due under the Notes and the Convertible  Notes in
     accordance with the terms thereof;

     (ii)  Second,  to the  Class A  Limited  Partners  in  proportion  to their
     respective  Percentage  Interests  in an  aggregate  amount  equal  to  the
     cumulative  amount  (including  interest) paid to the holders of the Notes;
     and

     (iii) Thereafter, to the Limited Partners in proportion to their Percentage
     Interests.

                                   ARTICLE IX

                   TRANSFERS; PARTNERSHIP REGISTRATION RIGHTS

Section  9.1  Incorporation  of Section 8 of the  Stockholders'  Agreement.  The
provisions of Section 8 of the Stockholders'  Agreement are hereby  incorporated
by reference in their entirety in this Agreement.

Section 9.2 Partnership  Registration  Rights.  Upon an Initial Public Offering,
the  Partnership  shall  grant  to  each  of  the  Limited  Partners   customary
registration rights in the securities of the Partnership  commensurate with such
Limited Partner's Percentage Interest,  provided,  that such rights shall not be
exercisable in connection  with the Initial Public  Offering  itself and further
provided that such registration rights shall be subject to the provisions of any
underwriting  agreement  entered  into by the  Partnership  with respect to such
Initial Public Offering.

                                   ARTICLE X

                                BOOKS AND RECORDS

Section 10.1      Books, Records and Financial Statements.
                  ---------------------------------------

(a) At all times during the continuance of the Partnership,  the General Partner
shall maintain  separate books of account for the Partnership  that shall show a
true and accurate record of all costs and expenses  incurred,  all charges made,
all credits  made and  received and all income  derived in  connection  with the
operation of the Partnership  business,  in accordance  with generally  accepted
accounting  principles  consistently applied to the extent not inconsistent with
this  Agreement.  Such books of account,  together with a copy of this Agreement
and of the Certificate of Limited Partnership,  shall at all times be maintained
at the  principal  place of  business  of the  Partnership  (or at the  place of
business  of the  Person  to whom  the duty to  maintain  these  books  has been
delegated  in  accordance  herewith  and  identified  in writing to the  Limited
Partners) and shall be open to inspection and examination at reasonable times by
each  Limited  Partner and its duly  authorized  representative  for any purpose
reasonably  related to such Limited  Partner's  interest as a Limited Partner of
the Partnership.

(b) The General Partner shall prepare and maintain,  or cause to be prepared and
maintained,  the books of account of the  Partnership.  The following  financial
information,  which shall be certified  to by an  independent  certified  public
accountant,  shall be transmitted by the General Partner to each Limited Partner
within four (4) months after the close of each Fiscal Year:

     (i) balance sheet of the  Partnership as of the beginning and close of such
     Fiscal Year;

     (ii) statement of Partnership profits and losses for such Fiscal Year;

     (iii) statement of such Limited  Partner's  Capital Account as of the close
     of such Fiscal Year, and changes therein during such Fiscal Year; and

     (iv)  statement  indicating  such Limited  Partner's  share of each item of
     Partnership  income,  gain, loss,  deduction or credit for such Fiscal Year
     for income tax purposes.

(c) Within  three (3) months  after the close of each Fiscal  Year,  the General
Partner  shall  send to each  Limited  Partner a Form K-1 tax  statement  or any
successor form thereto.

(d) The General  Partner  shall  prepare,  or cause to be  prepared,  such other
statements as it deems necessary or advisable.

Section 10.2 Accounting  Method.  For both financial and tax reporting  purposes
and for purposes of determining profits and losses, the books and records of the
Partnership  shall be kept on the  accrual  method of  accounting  applied  in a
consistent  manner  and  shall  reflect  all  Partnership  transactions  and  be
appropriate for the Partnership's business.

Section 10.3 Audit. The financial statements of the Partnership shall be audited
at the end of each Fiscal Year by an  independent  certified  public  accountant
selected by the General  Partner,  with such audit to be accompanied by a report
of such  accountant  containing its opinion.  The cost of such audits will be an
expense of the Partnership.  A copy of any such audited financial statements and
accountant's  report  will be  made  available  for  inspection  by the  Limited
Partners.

                                   ARTICLE XI

                                   TAX MATTERS

Section 11.1 Tax Matters  Partner.  A Required  Majority of the Limited Partners
shall designate a Limited Partner, with such Limited Partner's prior consent, as
the "Tax Matters  Partner" of the Partnership for purposes of ss.  6231(a)(7) of
the  Code.  The Tax  Matters  Partner  and shall  have the  power to manage  and
control,  on  behalf  of  the  Partnership,  any  tax  audit  or  administrative
proceeding at the Partnership  level with the Internal  Revenue Service relating
to the determination of any item of Partnership income, gain, loss, deduction or
credit for federal income tax purposes;  provided, however, that the Tax Matters
Partner shall not settle any tax audit or administrative  proceeding without the
consent of a majority in  interest of the  affected  Limited  Partners.  The Tax
Matters  Partner shall be fully  indemnified by the Partnership for all expenses
incurred  by the Tax  Matters  Partner  with  respect  to any such tax  audit or
administrative  proceeding.  The Tax  Matters  Partner  may be  replaced  by the
holders of a Required Majority of the Limited Partnership Interests.

Section 11.2 Election.  Upon the reasonable request of any Limited Partner,  the
Tax  Matters  Partner  shall  make or take all  reasonable  efforts to revoke an
election on behalf of the  Partnership,  in accordance with ss. 754 of the Code,
so as to adjust the basis of Partnership  property in the case of a distribution
of  property  within the  meaning  of ss. 734 of the Code,  and in the case of a
transfer of a  Partnership  interest  within the meaning of ss. 743 of the Code.
Each Limited Partner shall, upon request of the Tax Matters Partner,  supply the
information necessary to give effect to such an election.

Section 11.3 Taxation as  Partnership.  The Partners intend that the Partnership
will be treated as a partnership  for U.S.  federal  income tax purposes and, to
the extent permitted under applicable law, all other income tax purposes and the
Partner  will  take such  action,  as is  reasonably  requested  by the  General
Partner, to make all elections and perform all acts as are necessary to have the
Partnership treated as such.

                                  ARTICLE XII

                   LIABILITY, EXCULPATION AND INDEMNIFICATION

Section 12.1      Liability.
                  ---------

(a) Except as otherwise provided by the Delaware Act, the debts, obligations and
liabilities of the Partnership,  whether arising in contract, tort or otherwise,
shall be solely the debts,  obligations and liabilities of the Partnership,  and
no Covered Person shall be obligated personally for any such debt, obligation or
liability of the Partnership solely by reason of being a Covered Person.

(b) Except as otherwise  expressly  required by law, a Limited  Partner,  in its
capacity as Limited Partner, shall have no liability in excess of (a) the amount
of its Capital  Contributions  and its  obligations  hereunder  to make  Capital
Contributions,  (b) its share of any  assets  and  undistributed  profits of the
Partnership, (c) its obligation to make other payments expressly provided for in
this Agreement,  and (d) the amount of any distributions  wrongfully distributed
to it as determined under the Delaware Act.

Section 12.2      Exculpation.
                  -----------

(a) No Covered  Person shall be liable to the  Partnership  or any other Covered
Person for any loss,  damage or claim  incurred by reason of any act or omission
performed,  or omitted to be performed,  by such Covered Person in good faith on
behalf of the Partnership and in a manner  reasonably  believed to be within the
scope of authority  conferred on such Covered Person by this  Agreement,  except
that a  Covered  Person  shall be  liable  for any such  loss,  damage  or claim
incurred by reason of such Covered Person's  willful  misconduct,  fraud,  gross
negligence or breach of this Agreement.

(b) A Covered Person shall be fully  protected in relying in good faith upon the
records  of the  Partnership  and upon such  information,  opinions,  reports or
statements  presented to the Partnership by any Person as to matters the Covered
Person reasonably believes are within such other Person's professional or expert
competence and who has been selected with reasonable care by or on behalf of the
Partnership,  including information,  opinions,  reports or statements as to the
value and amount of the assets, liabilities, profits, losses, or any other facts
pertinent  to the  existence  and amount of assets from which  distributions  to
Limited Partners might properly be paid.

Section 12.3      Indemnification.
                  ---------------

(a) To the fullest extent permitted by applicable law, each Covered Person shall
be entitled to indemnification  from the Partnership for any loss, damage, claim
or liability  incurred by such  Covered  Person by reason of any act or omission
performed,  or omitted to be performed,  by such Covered Person in good faith on
behalf of the  Partnership  and within the scope of authority  conferred on such
Covered  Person  by this  Agreement,  except  that no  Covered  Person  shall be
entitled to be  indemnified in respect of any loss,  damage,  claim or liability
incurred by such Covered Person by reason of willful  misconduct,  fraud,  gross
negligence or breach of this  Agreement  with respect to such acts or omissions;
provided,  however, that any indemnity under this Section 12.3 shall be provided
out of and to the extent of Partnership assets only, and no Covered Person shall
have any personal liability on account thereof.

(b) If any claim shall be asserted against a Covered Person, in respect of which
such Covered Person proposes to demand  indemnification  under this Section 12.3
from the  Partnership,  such Covered Person shall notify the General  Partner to
that effect with reasonable  promptness  after such  assertion,  and the General
Partner on behalf of the  Partnership  shall have the right to assume the entire
control  of the  defense  or  settlement  of any  such  claim,  through  its own
attorneys and at its expense, and in connection  therewith,  such Covered Person
shall  cooperate  fully to make  available  to the  Partnership  and the General
Partner all information under its control relating thereto.

(c) All rights to indemnification  provided herein shall survive the termination
of this  Agreement  and the  withdrawal,  removal or  insolvency of any Partner;
provided, that a claim for indemnification  hereunder is made by or on behalf of
the Covered Person seeking such  indemnification  prior to the time distribution
in  liquidation  of the assets of the  Partnership  is made  pursuant to Article
XIII.

(d) The Partnership may enter into indemnity  contracts with Covered Persons and
adopt  written  procedures  pursuant  to  which  arrangements  are  made for the
advancement  of expenses and the funding of  obligations  under Section 12.4 and
containing such other procedures regarding indemnification as are appropriate.

Section  12.4  Expenses.  To the fullest  extent  permitted by  applicable  law,
expenses  (including  legal fees)  incurred by a Covered Person in defending any
claim, demand,  action, suit or proceeding shall, from time to time, be advanced
by the Partnership prior to the final disposition of such claim, demand, action,
suit or proceeding upon receipt by the Partner of an undertaking by or on behalf
of the Covered  Person to repay such amount if it shall be  determined  that the
Covered  Person is not entitled to be  indemnified as authorized in Section 12.3
hereof.

Section 12.5 Insurance.  The Partnership may purchase and maintain insurance, to
the extent and in such amounts as the General Partner shall deem  advisable,  on
behalf of Covered  Persons and such other  Persons as the General  Partner shall
determine,  against any liability that may be asserted  against or expenses that
may be incurred  by any such Person in  connection  with the  activities  of the
Partnership or such  indemnities,  regardless of whether the  Partnership  would
have the  power to  indemnify  such  Person  against  such  liability  under the
provisions of this Agreement.

Section 12.6 Outside  Businesses.  The parties  acknowledge that Covered Persons
have and may in the future  have  investments  in other  businesses  that may be
similar  to  or  competitive  with  the  Partnership  (collectively,  "Competing
Businesses")  independent of their investments in the Partnership.  By virtue of
its rights under this Section,  no Covered  Person shall have any  obligation to
the Partnership to refrain from making investments in Competing  Businesses,  or
otherwise engaging in any commercial  activity;  and neither the Partnership nor
any other Covered Person shall have any right hereunder with respect to any such
investments or activities undertaken by such Covered Person.  Without limitation
of the foregoing,  this Agreement  shall not be deemed to restrict the rights of
each  Covered  Person to engage in or  possess  an  interest  in other  business
ventures of any nature or description,  independently or with others, similar or
dissimilar to the business of the Partnership, and the Partnership and the other
Covered  Persons  shall have no rights or  expectancy  by virtue of such Covered
Person's relationships with the Partnership,  this Agreement or otherwise in and
to such independent ventures or the income or profits derived therefrom; and the
pursuit of any such venture, even if such investment is in a Competing Business,
shall not be deemed wrongful or improper  hereunder.  No Covered Person shall be
obligated to present any particular  investment  opportunity to the  Partnership
even  if  such  opportunity  is  of  a  character  that,  if  presented  to  the
Partnership,  could be pursued by the  Partnership,  and Covered  Persons  shall
continue  to have the  right to take for  their  own  respective  account  or to
recommend to others any such particular investment  opportunity.  The provisions
of this  Section 12.6 shall in no way limit or  eliminate  (i) Covered  Persons'
duties,  responsibilities  and  obligations  with  respect  to  any  proprietary
information of the Partnership, including any applicable duty not to disclose or
use such  proprietary  information  improperly  or obtain  therefrom an improper
personal  benefit,  or (ii)  Covered  Persons'  obligations  under  the  October
Investment  Agreement or any agreement,  instrument or  obligations  (other than
this Agreement).

                                  ARTICLE XIII

                    DISSOLUTION, LIQUIDATION AND TERMINATION

Section 13.1  Dissolution.  The  Partnership  shall be dissolved and its affairs
shall be wound up upon the first to occur of any of the following:

(a)  consent of Limited  Partners  and Note  Investors  holding  the  Percentage
Interests equal to at least eighty percent (80%); or

(b) the  occurrence  of any of the  events  set  forth in  Sections  5.7 and the
failure of the  Required  Majority to agree to continue the  Partnership  as set
forth therein; or

(c) the entry of a decree of judicial  dissolution  under Section  17-802 of the
Delaware Act.

Section 13.2 Notice of Dissolution. Upon the dissolution of the Partnership, the
General Partner shall promptly notify the Limited Partners of such dissolution.

Section 13.3  Liquidation.  Upon  dissolution  of the  Partnership,  the General
Partner or, if such dissolution has occurred in accordance with Section 13.1(b),
the Required Majority shall appoint a liquidating  trustee who shall immediately
commence  to  wind  up the  Partnership's  affairs;  provided,  however,  that a
reasonable  time shall be allowed for the orderly  liquidation  of the assets of
the Partnership and the satisfaction of liabilities to creditors so as to enable
the Limited  Partners and Note Investors to minimize the normal losses attendant
upon a  liquidation.  The Limited  Partners  shall continue to share Profits and
Losses during  liquidation in the same proportions,  as specified in Article VII
hereof, as before liquidation. The proceeds of liquidation shall be distributed,
as realized, in accordance with the provisions of Article VIII hereof.

Section 13.4 Termination. The Partnership shall terminate when all of the assets
of the  Partnership  have been  distributed  in the manner  provided for in this
Article  XIII,  and the  Certificate  of  Limited  Partnership  shall  have been
canceled in the manner required by the Delaware Act.

Section  13.5 Claims of the Limited  Partners.  The Limited  Partners and former
Limited Partners shall look solely to the Partnership's assets for the return of
their  Capital  Contributions,  and if the assets of the  Partnership  remaining
after payment of or due provision for all debts,  liabilities and obligations of
the  Partnership  are  insufficient  to return such Capital  Contributions,  the
Limited  Partners and former Limited Partners shall have no recourse against the
Partnership or any other Partner.

                                  ARTICLE XIV

                                   AMENDMENTS

Section 14.1  Amendments.  Any  amendments  to this  Agreement or any waivers or
consents hereunder,  shall be adopted and be effective as an amendment hereto or
waiver or consent  hereunder  only if approved by the Required  Majority and, if
such amendment,  waiver or consent would adversely affect the particular  rights
and interests of any Limited Partner or Note Investor  disproportionately to the
adverse  effects of such  action on the rights and  interests  of other  Limited
Partners,  such action shall also require the consent of such Limited Partner or
Note Investor;  provided,  however,  that no provision of this  Agreement  which
establishes a class vote and/or minimum Percentage Interest required to take any
action  shall  be  amended  in  any  respect  which  would  reduce  such  voting
requirement, unless such amendment is approved by such Limited Partners and Note
Investors   holding  at  least  the  Percentage   Interest   (determined  on  an
as-converted  basis) that would have been required to take the action  permitted
to be taken under the provision to be amended.

                                   ARTICLE XV

                                  MISCELLANEOUS

Section 15.1 Further  Assurances.  The Partners shall  cooperate with each other
and the  Partnership  and shall promptly  execute,  acknowledge  and deliver any
assurances,  approvals or documents  reasonably  requested by a Limited  Partner
that is necessary for the requesting  Partner or the  Partnership to satisfy its
obligations hereunder or obtain the benefits contemplated hereby.

Section 15.2 Notices.  All notices  provided for in this  Agreement  shall be in
writing,  duly signed by the party  giving such  notice,  and shall be delivered
personally,  sent by a nationally  recognized  overnight courier,  telecopied or
mailed by registered or certified mail, as follows:

(a) If given to the Partnership,  at the Partnership's mailing address set forth
below:

                           Mobile Satellite Ventures LP
                           10802 Parkridge Boulevard
                           Reston, Virginia  20191-5416
                           Fax:  (703) 758-6134
                           Attention:       General Counsel

                           with a copy to:

                           Mobile Satellite Ventures LP
                           c/o Telcom Ventures LLC
                           211 North Union Street, Suite 300
                           Alexandria, Virginia  22314
                           Fax:  (703) 706-3801
                           Attention:       Hal Perkins, Esq.

(b) If given to the General Partner,  at the General  Partner's  mailing address
set forth below:

                           Mobile Satellite Ventures GP, Inc.
                           10802 Parkridge Boulevard
                           Reston, Virginia  20191-5416
                           Fax:  (703) 758-6134
                           Attention:  General Counsel

          with a copy to each Limited Partner as set forth in clause (c) below.

(c) If given to any  Limited  Partner,  at the  address  set forth on Schedule I
hereof  (or as  modified  from time to time by a Limited  Partner  upon  written
notice to the General Partner).

(d) If given to any Note  Investors,  at the  address  set forth on  Schedule II
hereof (or as modified from time to time by a Note Investor upon written  notice
to the General Partner).

     Notices  delivered  personally to an addressee or sent by overnight courier
shall  be  deemed  to have  been  given  upon  such  delivery.  Notices  sent by
telecopier  shall be deemed to have been given  upon  confirmation  by  telecopy
answerback (provided that the sending of any such notice is followed promptly by
the mailing of the original of such  notice).  Notices  mailed by  registered or
certified  mail shall be deemed to have been given upon the  expiration  of five
(5) days after such notice has been deposited in the mail.

Section  15.3  Failure  to Pursue  Remedies.  The  failure  of any party to seek
redress  for  violation  of, or to insist  upon the strict  performance  of, any
provision of this Agreement shall not prevent a subsequent act, which would have
originally  constituted  a  violation  from  having  the  effect of an  original
violation.  No waiver of any breach of any of the terms of this Agreement  shall
be effective  unless such waiver is in writing and signed by the Partner against
whom such waiver is claimed.

Section  15.4  Cumulative  Remedies.  The rights and  remedies  provided by this
Agreement  are  cumulative  and the use of any one  right or remedy by any party
shall not  preclude  or waive its right to use any or all other  remedies.  Said
rights and  remedies  are given in addition to any other  rights the parties may
have by law, statute, ordinance or otherwise.

Section 15.5 Binding  Effect.  This Agreement shall be binding upon and inure to
the  benefit  of  all of the  parties  and,  to the  extent  permitted  by  this
Agreement, their successors, legal representatives and assigns.

Section 15.6 Severability.  The invalidity or unenforceability of any particular
provision of this Agreement shall not affect the other  provisions  hereof,  and
this  Agreement  shall  be  construed  in all  respects  as if such  invalid  or
unenforceable provision were omitted.

Section  15.7  Counterparts.  This  Agreement  may be  executed in any number of
counterparts  with the same effect as if all parties  hereto had signed the same
document.  All counterparts shall be construed together and shall constitute one
instrument.

Section 15.8 Integration.  This Agreement constitutes the entire agreement among
the  parties  hereto  pertaining  to the subject  matter  hereof and thereof and
supersedes all prior agreements and understandings pertaining thereto.

Section 15.9  Confidentiality.  Each Partner  acknowledges that in the course of
the  formation,  and during the  operation,  of the  Partnership it has or shall
receive confidential and proprietary information concerning the assets, business
plans,  intellectual  property  rights and operations of the Partnership and the
other Partners and Affiliates of such Persons ("Confidential Information"). Each
Partner  agrees that the  Confidential  Information  is a valuable  asset of the
Partnership  or its owner,  as the case may be and its public  disclosure or use
outside  of the  Partnership's  activities  without  the  prior  consent  of the
Partnership  and/or the relevant  Partner  would cause  substantial  harm to the
Partnership,  such disclosing Partner or other Person.  Therefore,  each Partner
agrees to treat all Confidential  Information  received by it with the amount of
care that a reasonable  business person would use to protect to its own valuable
and proprietary confidential information and shall not disclose any Confidential
Information  to any Person who does not have a contractual  obligation  with the
Partnership to keep such Confidential  Information confidential or does not have
the  right  to have  such  Confidential  Information  disclosed  to it  under an
agreement with the Partnership.  In addition, each Partner shall not personally,
and shall not  permit  other  Persons  (including  its  Affiliates)  to  utilize
Confidential  Information  for any  purpose  other  than for the  benefit of the
Partnership.

     Notwithstanding  the  foregoing,   a  Partner  may  disclose   Confidential
Information to its Affiliates,  professional advisors,  lenders and investors if
such Persons have agreed for the benefit of the Partnership,  to comply with the
provision of this Section 15.9.

     As used herein,  "Confidential  Information" shall not include  information
(i) that has become  generally  available to the public  through no fault of the
receiving  Person,  (ii) to the minimum extent necessary in order to comply with
any law, order,  regulation,  ruling or other  governmental  request pursuant to
subpoena or government  order,  provided that in the event a receiving Person is
subject to such a subpoena  or order,  it shall  notify in writing  the  General
Partner  of such  event,  and shall  cooperate  with any  reasonable  request or
efforts by the General Partner to take reasonable legally permissible actions to
limit the scope of  disclosure  required in order for such Person to comply with
such subpoena or order and (iii) as may be required or  appropriate  in response
to any report,  statement or  testimony  submitted  to any  municipal,  state or
national  (including  foreign  regulatory  bodies  having  or  claiming  to have
jurisdiction over such Person).

Section 15.10  Governing  Law;  Consent to  Jurisdiction  This Agreement and the
rights of the parties hereunder shall be interpreted in accordance with the laws
of the State of Delaware,  and all rights and remedies shall be governed by such
laws without  regard to principles of conflict of laws.  Each party agrees that,
in  connection  with any legal suit or  proceeding  arising with respect to this
Agreement,  it shall  submit to the  non-exclusive  jurisdiction  of the  United
States District Courts for the District of Delaware and the Southern District of
New York or the applicable  Delaware or New York state court and agrees to venue
in such courts.

Section 15.11     Third-Party Beneficiary.
                  -----------------------

The  parties  hereto  expressly  acknowledge  and  agree  that  each of the Note
Investors  (and  each  of  their   successors  and  assigns)  is  a  third-party
beneficiary  of the  Sections  hereof  defining  the  rights,  preferences,  and
privileges of the Limited Partners,  including without limitation,  Section 14.1
hereof, and this sentence,  and as such, may enforce such provisions against the
Partnership and shall have all rights and remedies of a third-party  beneficiary
with respect to such provisions.

                                      * * *

<PAGE>

     IN WITNESS  WHEREOF,  the parties hereto have executed this Agreement as of
the date first above written.

                                     GENERAL PARTNER:
                                     MOBILE SATELLITE VENTURES GP, INC.

                                     By:__________________________
                                     Name:
                                     Title:

                                     [MOTIENT SUB]
                                     By:__________________________
                                     Name:
                                     Title:

                                     [TMI SUB]

                                      By:__________________________
                                      Name:
                                      Title:

                                     INVESTORS:
                                     ---------

                                     EXISTING INVESTORS:
                                     ------------------

                                     TELCOM SATELLITE VENTURES INC.

                                     By:
                                        __________________________
                                        Name:
                                        Title:

                                     COLUMBIA SPACE (QP), INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     COLUMBIA SPACE (AI), INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     COLUMBIA SPACE PARTNERS, INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     SPECTRUM SPACE EQUITY
                                     INVESTORS IV, INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     SPECTRUM SPACE IV PARALLEL, INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     SPECTRUM SPACE IV MANAGERS, INC.

                                     By:__________________________
                                        Name:
                                        Title:

                                     DEAN & COMPANY

                                     By:__________________________
                                        Name:
                                        Title:

<PAGE>

                                   SCHEDULE I

                              CAPITAL CONTRIBUTIONS

                                LIMITED PARTNERS
<TABLE>
<CAPTION>

------------------------------ ------------------------------------ ----------------- ------------------- --------------------

                                                                        Number/          Percentage            Capital
            Name                             Address                 Type of Units         Interest          Contributions
            ----                             -------                 -------------         --------          -------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

<S>                            <C>                                  <C>                   <C>                    <C>
Motient Sub                    10802 Parkridge Boulevard            8,000,000             48.069032%             $1.00
                               -----------------------------------  Common Units
                               Reston, Virginia 20191-5416
                               Tel:  (703) 758-6130
                               Fax:  (703) 758-6134
                               Attention:  David Engvall, Vice
                               President and General Counsel

                               with a copy to:
                               Hogan & Hartson L.L.P.
                               8300 Greensboro Drive
                               Suite 1100
                               McLean, Virginia  22102
                               Tel:  (703) 610-6123
                               Fax:  (703) 610-6200
                               Attention:  Richard K.A. Becker,
                               Esq.
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Telcom Satellite Ventures      211 North Union Street               720,000 Class A       4.326213%           $18,000,000
Inc.                           Suite 300                            Preferred Units
                               Alexandria, Virginia 22314
                               Attention:  Hal B. Perkins
                               Tel:    (703) 706-3800
                               Fax:    (703) 706-3801
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Columbia Space (QP), Inc.      211 North Union Street               345,042.42            2.073232%           $8,626,061
                               Suite 300                            Class A
                   Alexandria, Virginia 22314 Preferred Units
                               Attention:  James Fleming
                               Tel:    (703) 519-3000
                               Fax:    (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Columbia Space (AI), Inc.      211 North Union Street               19,061.12 Class       0.114531%            $476,528
                              Suite 300 A Preferred
                               Alexandria, Virginia 22314           Units
                               Attention:  James Fleming
                               Tel:    (703) 519-3000
                               Fax:   (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen Meredith, Esq.
                               Tel:    (617) 951-2233
                               Fax:   (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Columbia Space Partners, Inc.  211 North Union Street               275,896.46            1.657759%           $6,897,411
                               Suite 300                            Class A
                   Alexandria, Virginia 22314 Preferred Units
                               Attention:  James Fleming
                               Tel:  (703) 519-3000
                               Fax:  (703) 519-3904
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:  (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
                               One International Place
Spectrum Space Equity          29th Floor                           618,048.00            3.713621%           $15,451,200
Investors IV, Inc.             Boston, MA 82110                     Class A
                               Attention:  Kevin Maroni             Preferred Units
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601
                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Spectrum Space IV Parallel,    One International Place              14,464.00             0.086909%            $361,600
Inc.                           29th Floor                           Class A
                        Boston, MA 82110 Preferred Units
                               Attention:  Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------

Spectrum Space IV Managers,    One International Place              7,488.00              0.044993%            $187,200
Inc.                           29th Floor                           Class A
                        Boston, MA 82110 Preferred Units
                               Attention: Kevin Maroni
                               Tel:    (617) 464-4600
                               Fax:   (617) 464-4601

                               with a copy to:
                               Edwards & Angell, LLP
                               101 Federal Street
                               Boston, MA 02100
                               Attention:  Stephen
                               Meredith, Esq.
                               Tel:   (617) 951-2233
                               Fax:  (888) 325-9120
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
                                                                    6,636,481.51
TMI Sub                        1601 Telesat Court                   Common Units          39.876156%             $1.00
                               Gloucester Court
                               Canada K1B 1B9
                               Attn:  Rory McCormick

                               with a copy to:
                               Salans Hertzfeld Heilbronn Christy
                                 & Viener

                               Rockefeller Center
                               620 Fifth Avenue
                               New York, NY  10020-2457
                               Attn:  Owen D. Kurtin, Esq.
                               Tel:  (212) 623-8374
                               Fax: (212) 632-5555

------------------------------ ------------------------------------ ----------------- ------------------- --------------------
------------------------------ ------------------------------------ ----------------- ------------------- --------------------
                               8065 Leesburg Pike
Dean & Company                 Vienna, VA  22182                    6,250 Common          0.037554%              $1.00
                               Attention:  Dean Wilde, Chairman     Units

------------------------------ ------------------------------------ ----------------- ------------------- --------------------

</TABLE>

<PAGE>

                                   SCHEDULE II

                          Note Investors Notice Address

MSV Investors LLC
c/o Rare Medium Group, Inc.
28 West 23rd Street
New York, New York 10010
Attention:  General Counsel
Tel:    (646) 638-9600
Fax:    (646) 638-9716

with a copy to:

Skadden, Arps, Slate, Meagher & Flom LLP
Four Times Square
New York, New York 10036
Attn:  Gregory A. Fernicola, Esq.
Tel: (212) 735-3000
Fax: (212) 735-2000

<PAGE>
                                TABLE OF CONTENTS

                                                                            Page

ARTICLE I DEFINED TERMS........................................................2

     Section 1.1      Definitions..............................................2

     Section 1.2      Headings.................................................9

     Section 1.3      Interpretation...........................................9

ARTICLE II CONTINUATION AND TERM...............................................9

     Section 2.1      Continuation.............................................9

     Section 2.2      Name....................................................10

     Section 2.3      Term....................................................10

     Section 2.4      Registered Agent and Office.............................10

     Section 2.5      Principal Place of Business.............................10

     Section 2.6      Qualification in Other Jurisdictions....................10

     Section 2.7      Agreement...............................................10

ARTICLE III PURPOSE AND POWERS OF THE PARTNERSHIP.............................11

     Section 3.1      Purpose.................................................11

     Section 3.2      Powers of the Partnership...............................11

     Section 3.3      Limitations on Partnership Powers.......................11

ARTICLE IV CAPITAL CONTRIBUTIONS AND CAPITAL ACCOUNTS.........................11

     Section 4.1      Capital Contributions...................................11

     Section 4.2      Status of Capital Contributions.........................12

     Section 4.3      Limited Partnership Interest............................12

     Section 4.4      Capital Accounts........................................12

ARTICLE V PARTNERS    13

     Section 5.1      Powers of Limited Partners..............................13

     Section 5.2      No General Partner Liability............................13

     Section 5.3      Actions of the Limited Partners.........................13

     Section 5.4      Partition...............................................13

     Section 5.5      Withdrawal..............................................13

     Section 5.6      Removal of the General Partner by Limited Partners......13

     Section 5.7      Bankruptcy, Resignation, Withdrawal, Etc. of
                      General Partner.........................................13

ARTICLE VI MANAGEMENT 14

     Section 6.1      Management by the General Partner.......................14

     Section 6.2      Restrictions............................................14

     Section 6.3      General Partner's Time..................................15

     Section 6.4      No Liability; Indemnity.................................15

     Section 6.5      Reliance by Third Parties...............................15

     Section 6.6      General Authority.......................................15

     Section 6.7      Limited Liability.......................................15

     Section 6.8      Special Purpose Provision...............................15

     Section 6.9      Grant of Power of Attorney..............................16

     Section 6.10     Terms of Grant..........................................16

     Section 6.11     Separate Form...........................................16

ARTICLE VII ALLOCATIONS.......................................................17

     Section 7.1      Profits and Losses......................................17

     Section 7.2      Special Allocations.....................................17

     Section 7.3      Allocation Rules........................................19

     Section 7.4      Section 704(c) of the Code..............................19

     Section 7.5      Uncertainties in Allocations and Distributions..........20

ARTICLE VIII DISTRIBUTIONS....................................................20

     Section 8.1      Distributions...........................................20

     Section 8.2      Distributions to Pay Taxes..............................20

     Section 8.3      Dissolution.............................................21

     Section 8.4      Withholding Taxes.......................................21

     Section 8.5      Limitations on Distribution.............................21

     Section 8.6      Capital Proceeds........................................21

ARTICLE IX TRANSFERS; PARTNERSHIP REGISTRATION RIGHTS.........................22

     Section 9.1      Incorporation of Section 8 of the
                      Stockholders' Agreement.................................22

     Section 9.2      Partnership Registration Rights.........................22

ARTICLE X BOOKS AND RECORDS...................................................23

     Section 10.1     Books, Records and Financial Statements.................23

     Section 10.2     Accounting Method.......................................23

     Section 10.3     Audit...................................................24

ARTICLE XI TAX MATTERS........................................................24

     Section 11.1     Tax Matters Partner.....................................24

     Section 11.2     Election................................................24

     Section 11.3     Taxation as Partnership.................................24

ARTICLE XII LIABILITY, EXCULPATION AND INDEMNIFICATION........................25

     Section 12.1     Liability...............................................25

     Section 12.2     Exculpation.............................................25

     Section 12.3     Indemnification.........................................25

     Section 12.4     Expenses................................................26

     Section 12.5     Insurance...............................................26

     Section 12.6     Outside Businesses......................................26

ARTICLE XIII DISSOLUTION, LIQUIDATION AND TERMINATION.........................27

     Section 13.1     Dissolution.............................................27

     Section 13.2     Notice of Dissolution...................................27

     Section 13.3     Liquidation.............................................27

     Section 13.4     Termination.............................................28

     Section 13.5     Claims of the Limited Partners..........................28

ARTICLE XIV AMENDMENTS........................................................28

     Section 14.1     Amendments..............................................28

ARTICLE XV MISCELLANEOUS......................................................28

     Section 15.1     Further Assurances......................................28

     Section 15.2     Notices.................................................28

     Section 15.3     Failure to Pursue Remedies..............................30

     Section 15.4     Cumulative Remedies.....................................30
     Section 15.5     Binding Effect..........................................30

     Section 15.6     Severability............................................30

     Section 15.7     Counterparts............................................30

     Section 15.8     Integration.............................................30

     Section 15.9     Confidentiality.........................................30

     Section 15.10    Governing Law; Consent to Jurisdiction..................31

     Section 15.11    Third-Party Beneficiary.................................31

<PAGE>

                                    Exhibit D
                         to October Investment Agreement

--------------------------------------------------------------------------------

                          LIMITED PARTNERSHIP AGREEMENT

                                       OF

                          MOBILE SATELLITE VENTURES LP

                             [__________] ____, 2001

--------------------------------------------------------------------------------

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00031-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00031-of-00352.parquet"}]]