SUBLEASE

This  Sublease  (this  "Sublease")  is entered into as of the 11th day of April,
1997, by and between OPEN MARKET, INC., a Delaware corporation (the "Landlord"),
having a business address of 245 First Street,  Cambridge,  Massachusetts  02142
and HPR INC., a Delaware  corporation (the "Tenant"),  having a business address
of 245 First Street, Cambridge, Massachusetts 02142.

         1.  Premises:  Landlord  hereby  leases the  Premises  (as  hereinafter
defined) to Tenant,  and Tenant hereby rents from Landlord said  Premises,  upon
the  terms and  conditions  hereinafter  set  forth.  The  Premises  consist  of
approximately  20,069  square  feet  located  on the  third  (3rd)  floor of the
building commonly known as The Riverview Complex,  245 First Street,  Cambridge,
Massachusetts  (the "Building"),  which Premises are shown outlined on the floor
plan annexed hereto and made a part hereof by reference.

         Subject to and in accordance  with the terms and  provisions of Section
14.2 of the Prime Lease (as  hereinafter  defined),  as an  appurtenance  to the
Premises,  beginning  on the  Commencement  Date and  ending  as of the  Parking
Termination Date (as defined in the Prime Lease),  as and to the extent received
by the Landlord from the Prime Landlord,  Landlord shall provide to Tenant,  and
Tenant  agrees to pay for,  Garage  Parking  Permits  (as  defined in the Master
Lease) for twenty-eight  (28) automobiles in the parking garage of the Building.
The  obligation  of the  Landlord  to provide  such  Garage  Parking  Permits is
expressly  subject to the receipt of said Garage Parking  Permits from the Prime
Landlord in accordance with the terms and provisions of the Prime Lease. Without
limitation, Tenant shall pay the Parking Charges (as defined in the Prime Lease)
assessed with respect to each of the Garage Parking Permits  received by Tenant,
on a monthly basis, as additional  rent, in accordance with the requirements set
forth in  Section  14.2(b)  of the  Prime  Lease.  The use of the  garage by the
Tenant,  and the use of the Garage Parking  Permits,  shall be subject to and in
accordance with all of the terms, conditions,  and restrictions set forth in the
Prime  Lease,  including,  without  limitation,  the  provisions  of  Article 14
thereof.

         2. Sublease:  Reference is hereby made to that certain  Lease,  between
Riverview  Building  Combined  Limited  Partnership,  as  landlord  (the  "Prime
Landlord"), and Open Market, Inc., as tenant, originally dated March 9, 1995, as
modified by that certain Letter  Agreement,  dated March 14, 1995,  that certain
Letter  Agreement,  dated April 18, 1995, that certain Amendment No. 1 to Lease,
dated April 15, 1995 and that certain  Amendment  No. 2 to Lease,  dated October
__, 1995  (collectively,  the "Prime Lease").  The Premises subleased  hereunder
comprise a portion of the space leased to Landlord,  as tenant,  under the Prime
Lease.  Except as otherwise  expressly provided herein, this Sublease is subject
to all of the terms,  conditions and  provisions of the Prime Lease,  and Tenant
shall (a) be bound with respect to the  Premises by all of the terms,  covenants
and  conditions  of the  Prime  Lease  and (b)  assume  as to the  Premises  all
obligations  and  liabilities  of  Landlord,  as tenant,  under the Prime Lease,
including,  without  limitation,  all  obligations  of  maintenance,  repair and
indemnity.  Tenant  shall not do or permit  to be done  anything,  or omit to do
anything,  or permit to be  omitted to be done  anything,  which is, or with the
giving of notice or the  passage of time or both  would be, a default  under the
Prime Lease or could cause such a default. Tenant agrees to abide by and perform
all of the covenants and conditions of the Prime Lease as if the same were fully
set forth herein to the extent that said covenants and conditions pertain to the
Premises  and/or the occupancy and use thereof by Tenant.  Tenant  agrees,  with
respect to the  Premises,  to be bound by and to perform  and to comply with the
Prime Lease as if it were the "tenant"  thereunder  and as if the  "premises" as
demised under the Prime Lease were the Premises demised under this Sublease.  If
the Prime Lease  shall  terminate  for any reason  prior to the  termination  or
expiration of this Sublease,  this Sublease shall terminate as if such date were
the termination date of this Sublease.

         3. Term:  The term of this Sublease  shall  commence on April 15, 1997,
and,  unless  earlier  terminated as herein  provided,  shall end on January 31,
2001.

         4. Rent: During the term of this Sublease, commencing on July 15, 1997,
and thereafter throughout the term hereof, Tenant shall pay to Landlord, without
offset,  setoff or  deduction,  of any kind,  base rent at the per annum rate of
Four Hundred  Twenty-One  Thousand,  Four Hundred  Forty-Nine and 00/100 Dollars
($421,449.00), payable on the first day of each month in monthly installments of
Thirty-Five  Thousand,  One Hundred Twenty and 75/100 Dollars  ($35,120.75)  and
proportionately  at the  applicable  rate for any partial month during the term.
Commencing on the Commencement  Date and thereafter  throughout the term of this
Sublease,  Tenant  shall  also pay  Landlord,  on the first day of each month an
amount equal to Tenant's Share (as  hereinafter  defined) of amounts  payable by
Landlord to Prime Landlord pursuant to the Master Lease on account of additional
rent, including, without limitation, all amounts payable under Articles 5, 6 and
7 of the Prime Lease on account of Operating Costs and Taxes.

         As used in this Sublease,  the "Tenant's Share" is 24.77%, which is the
ratio that the  approximate  rentable area of the Premises bears to 81,020,  the
area leased by the Landlord, as tenant, pursuant to the Prime Lease.

         5. AS-IS CONDITION;  Construction: Tenant accepts the Premises in their
condition AS IS at the  commencement  of the term of this  Sublease and Landlord
shall have no obligation to prepare the  Premises,  or to make any  improvements
therein.  If Tenant  desires to make any additions,  alterations,  improvements,
installations,  demolition,  remodeling, repainting, decoration or other similar
activities  in or to the  Premises,  in each  instance it shall first obtain the
written  consent  of  Landlord  thereto,  such  consent  not to be  unreasonably
withheld. All such alterations,  additions and improvements shall conform to and
be governed by the provisions of the Prime Lease, including, without limitation,
the  provisions of Article 11 of the Prime Lease.  In  connection  with any work
performed  by  Tenant in the  Premises,  Tenant  shall  maintain  the  insurance
coverages  required  under  Section  12.1  of  the  Prime  Lease,  naming  as an
additional  insured party Landlord as well as Prime Landlord.  Tenant shall pay,
as additional  rent, one hundred  percent (l00%) of any increases in real estate
taxes  on  the  Building  which  may  result  from  alterations,   additions  or
improvements to the Premises made by Tenant.

         Tenant agrees to pay promptly when due the entire cost of any work done
on the Premises by Tenant, its agents,  employees or independent contractors and
not to cause or permit any liens for labor or  materials  performed or furnished
in connection therewith to attach to the Premises or the Building or the Project
(as said term is defined in the Prime Lease) and  immediately  to discharge  any
such liens which may so attach.

         6.  Use:  The  Premises  may be used  only  as  permitted  pursuant  to
Subsection  1(j) and  Article 9 of the Prime  Lease and for no other  purpose or
purposes.

         7. Utilities:  Tenant shall pay for all utilities consumed by it in the
Premises,  such  payments  to be made  directly  to the  utility  company if the
utility is metered separately to the Premises.  If not separately metered,  then
Tenant shall pay to Landlord on account of utilities, Tenant's Share of payments
made by  Landlord  to the  suppliers  of the  same,  or such  greater  or lesser
percentage as Landlord reasonably  determines to be appropriate if Tenant uses a
greater  or lesser  pro-rata  quantity  of  utilities  than  Landlord  and other
occupants of Landlord's premises.

         Landlord  shall not in any way be liable or  responsible  to Tenant for
any loss,  damage or expense  which  Tenant may sustain or incur if,  during the
term of this  Sublease,  either the quantity or the  character of the  utilities
servicing  the  Premises is changed or is no longer  available  or suitable  for
Tenant's  requirements due to a fact or cause beyond Landlord's control.  Tenant
at its expense shall purchase and install all lamps, tubes, bulbs,  starters and
ballasts on the Premises.

         8. HVAC  Charges:  Tenant  agrees to pay all  after-hours  HVAC charges
payable with respect to the  Premises  pursuant to Section  10.1(b) of the Prime
Lease.

         9.  Assignment  and  Subletting:  Tenant  shall not  assign,  sublease,
mortgage,  pledge,  encumber,  sell,  convey,  subject to a  security  interest,
license or otherwise transfer, whether voluntarily,  involuntarily, by operation
of law or otherwise,  the Premises,  this Sublease or the term and estate hereby
granted or any interest herein or therein,  in whole or in part, and neither the
Premises  nor any part  thereof will be used or occupied or permitted to be used
or occupied by anyone  other than Tenant or for any use or purpose  other than a
use which is permitted  hereunder or be offered or advertised  for assignment or
subletting without, in each instance,  having first received the express written
consent of Landlord  and Prime  Landlord,  such  consent by  Landlord  not to be
unreasonably withheld. The provisions of the foregoing sentence shall apply to a
transfer (by one or more  transfers) of  forty-nine  percent (49%) of the common
stock of Tenant as if such transfer of the Tenant's  stock were an assignment of
this  Sublease.   Whether  or  not  Prime  Landlord  or  Landlord  consents,  no
assignment,  sublease, etc. will release or alter the liability of Tenant to pay
rent and perform all of Tenant's  other  obligations  under this  Sublease.  The
acceptance of rent by Landlord from any person other than Tenant is not a waiver
by Landlord. Consent to one assignment,  sublease, etc. will not be deemed to be
consent to any subsequent assignment,  sublease,  etc. If Tenant or any assignee
or  sublessee,  defaults  under this  Sublease,  Landlord  may proceed  directly
against  the  Tenant  or said  assignee  or  sublessee,  without  proceeding  or
exhausting its remedies  against the other.  After any assignment,  Landlord may
consent to a subsequent  assignment,  sublease,  etc. of or  amendments  to this
Sublease,  without  notifying  Tenant or any  other  person,  without  obtaining
consent  thereto,  and without  relieving  Tenant of its liabilities  under this
Sublease.  As additional  rent,  Tenant shall  reimburse  Landlord  promptly for
reasonable legal and other expenses  incurred by Landlord in connection with any
requests by Tenant for consent to assignment or  subletting.  The  provisions of
Article  17 of the Prime  Lease are  hereby  made  expressly  applicable  to the
Tenant,  so that any assignment,  sublease or other transfer shall be subject to
the  conditions,  provisions and  requirements  of Article 17 and Landlord shall
have against  Tenant all the rights and remedies with respect to any  assignment
or subletting which are afforded to the Prime Landlord  pursuant to said Article
17.

         10.  Maintenance and Repairs:  It is understood that Prime Landlord has
certain  obligations to repair and maintain the Premises and the Building as set
forth in Section 10.1 and Articles 15 and 16 of the Prime Lease.  Landlord shall
have no obligation or liability to Tenant in the event that Prime Landlord fails
to perform any such  obligations.  Tenant  agrees that it will keep the Premises
neat and clean and maintain the  Premises in good order,  condition  and repair,
excepting only for ordinary wear and tear, and damage by fire and other casualty
and as a  consequence  of the  exercise of the power of eminent  domain.  Tenant
shall surrender the Premises and all  alterations,  improvements,  and additions
thereto at the end of the term of this  Sublease  in good order,  condition  and
repair,  first removing all goods and effects of Tenant and repairing any damage
caused by such  removal and  restoring  the  Premises and leaving them clean and
neat.  Tenant  shall  not  permit or  commit  any  waste,  and  Tenant  shall be
responsible  for the cost of repairs which may be necessary by reason of damages
to  common  areas  in  the  Building  or to  the  Project  by  Tenant,  Tenant's
contractors or Tenant's invitees.

         11.  Landlord's  Self-Help:  If Tenant shall at any time default in the
performance  of any  obligation  under this  Sublease,  Landlord  shall have the
right,  but shall not be  obligated,  to enter upon the  Premises and to perform
such obligation on behalf of the Tenant. In performing such obligation, Landlord
may make any  payment  of money or perform  any other  act.  All sums so paid by
Landlord  (together  with  interest at the per annum  interest rate of the prime
rate as set from time to time by The First  National  Bank of Boston  plus three
hundred (300) basis points) and all necessary  incidental  costs and expenses in
connection with the performance of any such act by Landlord,  shall be deemed to
be  additional  rent  under  this  Sublease  and shall be  payable  to  Landlord
immediately  on demand.  Landlord  may  exercise the  foregoing  rights  without
waiving any other of its rights or releasing  Tenant from any of its obligations
under this Sublease.

         12.  No  Damage:  Landlord  shall  not be  liable  to  Tenant  for  any
compensation or reduction of rent by reason of inconvenience or annoyance or for
loss of business  arising from the  necessity  of Landlord or Prime  Landlord or
their respective agents entering the Premises for any purpose in the Prime Lease
authorized,  or for  repairing  the  Premises  or any  portion of said  Building
however  the  necessity  may occur.  In case  Landlord  (or Prime  Landlord)  is
prevented or delayed from making any repairs,  alterations or  improvements,  or
furnishing any services or performing any other covenant or duty to be performed
on its  part,  by  reason of any cause  reasonably  beyond  Landlord's  control,
including,  without limitation,  strike, lockout, breakdown,  accident, order or
regulation  of or by any  Governmental  authority,  or  failure  of  supply,  or
inability by the exercise of reasonable  diligence to obtain supplies,  parts or
employees  necessary  to  furnish  such  services,  or  because  of war or other
emergency,  or for any cause  due to any act or  neglect  of Tenant or  Tenant's
servants,  agents,  employees,  licensees or any person  claiming by, through or
under  Tenant,  neither  Landlord nor Prime  Landlord  shall be liable to Tenant
therefor,  nor, except as expressly  otherwise provided in this Sublease,  shall
Tenant be entitled to any abatement or reduction of rent by reason thereof,  nor
shall  the same  give  rise to a claim  in  Tenant's  favor  that  such  failure
constitutes  actual  or  constructive,  total  or  partial,  eviction  from  the
Premises.

         13.      Indemnity and Insurance:

         13.1  To the  maximum  extent  this  agreement  may be  made  effective
according to law, Tenant agrees to indemnify and save harmless Landlord from and
against  all  claims  of  whatever  nature  arising  from any act,  omission  or
negligence of Tenant,  or Tenant's  contractors,  licensees,  invitees,  agents,
servants or employees, or arising from any accident, injury or damage whatsoever
caused to any person, or to the property of any person, occurring after the date
that  possession of the Premises is first  delivered to Tenant and until the end
of the Term of this Sublease and thereafter so long as Tenant is in occupancy of
any part of the Premises, in or about the Premises or arising from any accident,
injury or damage  occurring  outside the  Premises but within the Building or on
the Project,  where such accident,  injury or damage  results,  or is claimed to
have resulted,  from an act or omission on the part of Tenant or Tenant's agents
or employees, licensees, invitees or contractors.

         Without limiting the foregoing, Tenant will indemnify both Landlord and
Prime  Landlord,  and  hold  Landlord  and  Prime  Landlord  harmless  from  all
Liabilities (as defined in the Prime Lease) arising from or in connection  with:
acts or omissions of Tenant or its Affiliates (as defined in the Prime Lease) or
the conduct of Tenant's business;  injuries,  death or damage occurring in or on
the Premises (except if and to the extent caused directly by Landlord's or Prime
Landlord's  negligence  or  willful  misconduct  in  breach  of this  Sublease);
Tenant's  breach of or default  under this  Sublease;  claims  made by  Tenant's
Affiliates  against the  Landlord or Prime  Landlord if Tenant has waived  those
claims in this Sublease or Landlord or Prime  Landlord  would not be responsible
to Tenant for such  claims if such  claims  were made by Tenant  hereunder;  and
claims  made by or  Liabilities  to  Tenant's  Affiliates  or other  persons  if
Landlord or Prime Landlord, as applicable, declines to consent to any act, event
or  document  requiring  Landlord's  or  Prime  Landlord's  consent  under  this
Sublease.

         The  foregoing  indemnity and hold  harmless  agreements  shall include
indemnity  against  all  costs,  expenses  and  liabilities  incurred  in  or in
connection with any such claim or proceeding  brought  thereon,  and the defense
thereof with counsel acceptable to Landlord.

         l3.2  Tenant  agrees to maintain in full force from the date upon which
Tenant first enters the  Premises  for any reason,  throughout  the term of this
Sublease,  and thereafter,  so long as Tenant is in occupancy of any part of the
Premises, the policies of general liability and property damage insurance of the
type and in the  amounts  and subject to the  conditions  which are  required of
under  Section 12.1 of the Prime Lease which  policies  shall name  Landlord and
Prime Landlord as insured  parties.  Tenant agrees that, as a condition to first
entering  upon the  Premises,  Landlord  shall  be  furnished  with a  duplicate
original or  certificate  of the  insurance  required to be maintained by Tenant
under this Section 13.2.

         13.3 To the maximum  extent that this  agreement may be made  effective
according to law,  Tenant  agrees to use and occupy the Premises and to use such
other  portions of the Building and the common areas of the Project as Tenant is
here given the right to use at Tenant's  own risk;  and  Landlord  shall have no
responsibility  or  liability  for any loss of or  damage to  fixtures  or other
personal property of Tenant.  The provisions of this Section shall be applicable
from and after the  execution of this  Sublease and until the end of the term of
this  Sublease,  and  during  such  further  period as  Tenant  may use or be in
occupancy of any part of the Premises or of said Building.

         13.4 To the maximum  extent that this  agreement may be made  effective
according to law, Tenant agrees that Landlord shall not be responsible or liable
to Tenant,  or to those  claiming by,  through or under Tenant,  for any loss or
damage that may be  occasioned  by or through the acts or  omissions  of persons
occupying  adjoining  premises or any part of premises adjacent to or connecting
with the Premises or any part of said Building, or otherwise, or for any loss or
damage resulting to Tenant or those claiming by, through or under Tenant, or its
or their property, from the breaking,  bursting, stopping or leaking of electric
cables and wires,  and water,  gas, sewer or steam pipes.  Without  limiting the
foregoing,  the Tenant hereby agrees that all of the waivers,  limitations,  and
exculpations   set  forth  in  Section  13.2  of  the  Prime  Lease  are  hereby
incorporated herein, and are made by and on behalf of the Tenant as if fully and
completely set forth herein.

         14. Fire Damage and Taking:  If during the term hereof the  Premises or
the  Building  shall,  in whole or in part,  be damaged or  destroyed by fire or
other  casualty or taken by eminent  domain,  then Tenant may elect to terminate
this  Sublease  by notice to such  effect  given to Tenant  and  thereupon  this
Sublease  shall  terminate  as if the  date  of  termination  were  the  date of
expiration  hereof.  In  the  event  that  either  Prime  Landlord  or  Landlord
terminates the Prime Lease pursuant to Section 15.2 thereof, this Sublease shall
terminate as of the date of such termination of the Prime Lease. If, as a result
of any  damage  by fire or other  casualty  or  taking by  eminent  domain,  the
Premises are rendered untenantable in whole or in part, and this Sublease is not
terminated as aforesaid,  the base rent payable hereunder shall be equitably and
proportionately  abated to the extent the Premises are not useable by Tenant, it
being  understood  that  Landlord  has no  obligation  to make any  effort to so
restore. All proceeds,  income, rent, awards and interest in connection with any
Condemnation  will belong to Prime Landlord and/or Landlord,  whether awarded as
compensation  for  diminution  of value to the  leasehold  improvements,  or the
unexpired portion of this Lease, or otherwise.  Tenant waives all claims against
Prime  Landlord  and/or  Landlord  and the  condemning  authority  with  respect
thereto,  but nothing in this Section  prevents  Tenant from bringing a separate
action  against the  condemning  authority for moving costs or for lost goodwill
(as long as this  separate  action does not  diminish  Prime  Landlord's  and/or
Landlord's recovery).

         15. Default: If (a) Tenant shall fail to pay the fixed rent, additional
rent or other  charges for which  provision is made herein on or before the date
on which the same become due and payable,  and the same  continues  for five (5)
days after notice from Landlord thereof, or

         (b)  Landlord  having   rightfully   given  the  notice   specified  in
subdivision  (a) above  more than  twice in a period of 365 days,  Tenant  shall
thereafter  in the same  365-day  period fail to pay the fixed rent,  additional
rent or other  charges on or before the date on which the same  becomes  due and
payable, or

         (c)      Tenant shall cause a default under the Prime Lease, or

         (d)  Tenant  shall  fail to  perform  or  observe  any  other  terms or
condition  contained in this Sublease and Tenant shall not commence to cure such
failure  within  twelve (12)  business days after notice from Landlord to Tenant
thereof and promptly and diligently complete the curing of the same, or

         (e) The estate  hereby  created shall be taken on execution or by other
process of law and such taking shall not be discharged  within ten (10) days, or
if Tenant shall be insolvent,  or if any assignment or arrangement shall be made
of the  property  of Tenant for the  benefit  of  creditors,  or if a  receiver,
guardian,  conservator,  trustee in bankruptcy or other similar officer shall be
appointed to take charge of all or any substantial part of Tenant's  property by
a court of competent  jurisdiction  and such proceeding is not dismissed  within
sixty (60) days after such appointment,  or if a petition shall be filed for the
reorganization  of Tenant under any  provisions  of the  Bankruptcy  Code now or
hereafter  enacted and such  proceeding is not dismissed  within sixty (60) days
after it is begun,  or if Tenant shall file a petition for such  reorganization,
or for arrangements under any provisions of the Bankruptcy Code now or hereafter
enacted and providing a plan for a debtor to settle,  satisfy or extend the time
for payment of debts,

-- then,  and in any of said  cases  (notwithstanding  any  license  of a former
breach of  covenant  or  waiver of the  benefit  hereof or  consent  in a former
instance),  Landlord  lawfully may,  immediately or at any time thereafter,  and
without  demand or notice,  enter into and upon the Premises or any part thereof
in the name of the whole and repossess the same as of Landlord's  former estate,
and expel  Tenant and those  claiming  through or under Tenant and remove its or
their  effects  without  being  guilty of any manner of  trespass,  and  without
prejudice to any remedies  which might  otherwise be used for arrears of rent or
preceding breach of covenant, and, upon entry as aforesaid,  Landlord shall have
the right, by suitable  notice to Tenant,  forthwith to terminate this Sublease;
and Tenant  covenants  and  agrees,  notwithstanding  any entry or  re-entry  by
Landlord, whether by summary proceedings,  termination, or otherwise, to pay and
be liable  for, on the days  originally  fixed  herein for the payment  thereof,
amounts equal to the several  installments of rent and other charges reserved as
would,  under the terms of this  Sublease,  become due if this  Sublease had not
been terminated or if Landlord had not entered or re-entered,  as aforesaid, and
whether the Premises be relet or remain  vacant,  in whole or in part,  or for a
period less than the remainder of the Term of this  Sublease,  and for the whole
thereof,  but, in the event the Premises be relet by  Landlord,  Tenant shall be
entitled  to a credit in the net amount of rent and other  charges  received  by
Landlord in reletting, after deduction of all expenses incurred in reletting the
Premises (including,  without limitation,  remodeling costs,  brokerage fees and
the like), and in collecting the rent in connection therewith,  in the following
manner:

         Amounts  received by Landlord  after  reletting  shall first be applied
against such Landlord's expenses,  until the same are recovered,  and until such
recovery,  Tenant  shall pay, as of the day when a payment  would fall due under
this  Sublease,  the amount  which Tenant is obligated to pay under the terms of
this Sublease (Tenant's  liability prior to any such reletting and such recovery
not in any way to be  diminished  as a result of the fact  that  such  reletting
might be for a rent higher than the rent  provided for in this  Sublease);  when
and if such expenses have been completely  recovered,  the amounts received from
reletting  by Landlord as have not  previously  been  applied  shall be credited
against Tenant's  obligations as of each day when a payment would fall due under
this Sublease,  and only the net amount  thereof shall be payable by Tenant.  No
credit of any kind shall be due for any  period  after the date when the term of
this Sublease is scheduled to expire according to its terms.

         As an alternative,  at the election of Landlord, Tenant will, upon such
termination,  pay to Landlord,  as liquidated damages, such a sum as at the time
of such  termination  represents the amount of the excess,  if any, of the fixed
rent and  additional  rent which  would  have  accrued  to  Landlord  under this
Sublease for the  remainder of the Term of this  Sublease if the Lease terms had
been fully  complied with by Tenant,  discounted at eight percent (8%) per annum
to the date of  termination,  over and  above  the then  cash  rental  value (in
advance) of the Premises for the balance of the term of this Sublease.

         Nothing  contained in this Sublease  shall limit or prejudice the right
of Landlord to prove for and obtain in proceedings  for bankruptcy or insolvency
by reason of the  termination of this  Sublease,  an amount equal to the maximum
allowed by any statute or rule of law in effect at the time when,  and governing
the  proceedings  in which,  the  damages  are to be proved,  whether or not the
amount be  greater,  equal to,  or less than the  amount of the loss or  damages
referred to above.

         16.      Miscellaneous.

         16.1  Failure  on the part of  Landlord  to  complain  of any action or
non-action on the part of Tenant no matter how long the same may continue, shall
never  be a  waiver  by  Landlord  of any of the  Landlord's  rights  hereunder.
Further, no waiver at any time of any of the provisions hereof by Landlord shall
be construed as a waiver of any of the other  provisions  hereof and a waiver at
any time of any of the  provisions  hereof shall not be construed as a waiver at
any subsequent time of the same provisions.  The consent or approval of Landlord
to or of any action by Tenant  requiring  such consent or approval  shall not be
construed to waive or render unnecessary Landlord's consent or approval to or of
any  subsequent  similar act by Tenant.  No payment by Tenant or  acceptance  by
Landlord of a lesser  amount than shall be due from Tenant to Landlord  shall be
treated  otherwise  than as a payment on  account.  Acceptance  by Landlord of a
check for a lesser amount with  endorsement  or statement  thereon,  or upon any
letter  accompanying  such check,  that such  lesser  amount is payment in full,
shall be given no effect,  and Landlord may accept such check without  prejudice
of any other rights or remedies which Landlord may have against Tenant.

         16.2 No act or thing done by Landlord  during the term of this Sublease
shall be deemed an acceptance of a surrender of the premises and no agreement to
accept such surrender shall be valid,  unless in writing signed by Landlord.  No
employee of Landlord or of  Landlord's  agent shall have any power to accept the
keys to the Premises  prior to  termination of the Lease and delivery of keys to
any  employee  or agent  shall  not  operate  as  termination  of the Lease or a
surrender of the Premises.

         16.3 Tenant  warrants and represents that Tenant has not dealt with any
Broker other than the Columbia Group in connection with this Sublease and hereby
agrees to indemnify  and hold  harmless  Landlord with respect to all claims for
brokerage  commissions  or fees arising out of or resulting  from this Sublease,
excepting only claims made by the Columbia Group.

         16.4 If any  term or  provision  of this  Sublease  or the  application
thereof to any person or circumstance  shall be invalid or  unenforceable to any
extent,  the  remainder  of this  Sublease  or the  application  of such term or
provision  to persons or  circumstances  other than those as to which it is held
invalid  or  unenforceable  shall  not be  affected  thereby  and each  term and
provision of this Sublease  shall be valid and be in force to the fullest extent
permitted by law.

         16.5 Tenant,  subject to the terms and  provisions of this Sublease and
to Tenant's  timely paying rent and  observing and keeping or performing  all of
the terms and provisions of this Sublease on Tenant's part to be observed,  kept
and performed,  shall  lawfully,  peaceably and quietly have,  hold,  occupy and
enjoy  the  Premises  during  the term of this  Sublease  without  hindrance  or
objection  by any  persons  claiming  under the  Landlord  to have  title to the
Premises  superior to Tenant. It is understood and agreed that this covenant and
any and all other  covenants  of Landlord  contained in this  Sublease  shall be
binding upon Landlord and  Landlord's  successors  only with respect to breaches
occurring during Landlord's and Landlord's  successor's  respective ownership of
Landlord's  interest  hereunder.  In no event shall  Landlord  ever be liable to
Tenant  for any loss of  business  or any other  direct,  indirect,  special  or
consequential damages suffered by Tenant for whatever cause.

         16.6 The obligations of this Sublease shall enure to the benefit of and
be binding  upon the  successors  and  assigns,  respectively,  of Landlord  and
Tenant.  Each term and each provision of this Sublease to be performed by Tenant
shall be construed to both a covenant and a condition.

         16.7 Notices  shall be deemed given when sent by  recognized  overnight
delivery  service such as Federal  Express,  or  registered  or certified  mail,
postage prepaid: if to the Landlord at:

                  245 First Street
                  Cambridge, Massachusetts 02142

         and if to the Tenant at:

                  245 First Street
                  Cambridge, Massachusetts 02142

         All such notices shall be effective  when  deposited with said delivery
services or in the United States mails within the continental United States.

         Either party may change the address to which  notices are to be sent to
it by notice to the other party given under this Section 16.7.

         16.8  Tenant  will  promptly  furnish to  Landlord,  or to anyone  whom
Landlord  designates  a  statement,  in  writing  of the  status  of any  matter
pertaining to this Sublease,  including without  limitation,  acknowledgment (to
the extent to which) each party is in compliance with its obligations  under the
terms of this Sublease.

         16.9 Any insurance carried by either party with respect to the Premises
or property therein or thereon shall if it can be so written without  additional
premium or with additional  premium which the other party agrees to pay, include
a clause or endorsement denying to the insurer rights of subrogation against the
other  party to the  extent  rights  have been  waived by the  insured  prior to
occurrence of injury or loss. Each party, notwithstanding any provisions of this
Sublease to the contrary, hereby waives any rights of recovery against the other
for injury or loss due to assets covered by such insurance.

         16.10 This Lease shall be governed exclusively by the provisions hereof
and by the law of the Commonwealth of  Massachusetts,  as the same may from time
to time exist.

         16.11 Any holding over by Tenant at the  expiration of the term of this
Sublease  shall be treated as a tenancy at  sufferance  at one hundred and fifty
percent  (150%)  of the rents and other  charges  herein  (pro  rated on a daily
basis)  and shall  otherwise  be on the terms and  conditions  set forth in this
Sublease as far as  applicable.  In the event that  Tenant  enters into a direct
agreement  with  Prime  Landlord  relating  to the  Premises  for a  term  which
commences on the next day following the expiration of the term of this Sublease,
then Tenant's  remaining in the Premises  shall not be considered a holding over
for purposes of this Section 16.11.

         16.12  Employees  or agents of Landlord  have no  authority  to make or
agree  to make a lease or any  other  agreement  or  undertaking  in  connection
herewith.  The submission of this document for examination and negotiation  does
not  constitute an offer to lease,  reservation  of, or option for the Premises.
This  document  shall become  effective  and binding only upon the execution and
delivery  hereof by both  Landlord  and  Tenant,  and if the  approval  of Prime
Landlord is necessary thereto, upon the approval of Prime Landlord.

         WITNESS the execution under seal as of this 11th day of April, 1997.


                  OPEN MARKET, INC.


                  By: /s/ Regina O. Sommer
                      Name: Regina O. Sommer
                  Its: Senior Vice President and Chief Financial Officer
                                                          
                            Hereunto duly authorized


                 HPR INC.


                 By: /s/ Brian D. Cahill
                     Brian D. Cahill
                 Its: Chief Operating Officer
                            
                            Hereunto duly authorized