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                                                                    Exhibit 10.6


                           SECOND AMENDED AND RESTATED
                          REGISTRATION RIGHTS AGREEMENT


      This Second Amended and Restated Registration Rights Agreement (the
"Agreement") amending and restating that certain Registration Rights Agreement,
dated as of September 27, 1996 as amended on February 19, 1997 and restated on
April 28, 1997, by and among Synchronicity, Inc., a Massachusetts corporation
(the "Company"), Wheatley Partners, L.P. and Wheatley Foreign Partners, L.P.
(the "Series B Investors"), Canaan Capital Limited Partnership, Canaan Capital
Offshore Limited Partnership, C.V., Canaan S.B.I.C., L.P., Mark A. Ross, David
Spitzman, Thomas Bouzane, Mark Barlow and Richard Byrd (collectively, with the
Series B Investors, the "Series C Investors") and Pioneer Capital Corporation,
Canaan Equity, L.P., Marek Skoskiewicz, Synopsys, Inc. and Intel Corporation
(collectively, with the Series B Investors and Series C Investors, with the
exception of Thomas Bouzane and Richard Byrd, the "Series D Investors" and the
Series B Investors, Series C Investors and the Series D Investors are sometimes
hereinafter collectively referred to as the "Investors") is entered into as of
September 28, 1998.

                                    RECITALS

      WHEREAS, pursuant to the terms of, and in order to induce the Series D
Investors to enter into that certain Series D Convertible Preferred Stock
Purchase Agreement of even date herewith between the Company and the Series D
Investors (the "Stock Purchase Agreement"), the parties hereto have agreed to
provide for the registration rights set forth in this Agreement.

      NOW, THEREFORE, the parties to this Agreement hereby agree as follows:

      1. Amendment and Restatement of the Registration Rights Agreement. The
Company, the Series B Investors and the Series C Investors, pursuant to Section
13(k) of the Registration Rights Agreement hereby agree that the Registration
Rights Agreement is amended and restated in its entirety as set forth in this
Agreement.

      2. Definitions. For all purposes of this Agreement, the following terms
shall have the meanings set forth below (capitalized terms used herein and not
otherwise defined herein shall have the meaning set forth in the Stock Purchase
Agreement for such term):

            Commission means the Securities and Exchange Commission, or any
      successor agency.

            Common Stock means (a) the Common Stock (as defined in the Stock
      Purchase Agreement), and (b) any shares of any other class of capital
      stock of the Company hereafter issued which is (i) not preferred in the
      Company's Amended and Restated Articles of Organization, as amended (the
      "Charter"), as to dividends or to assets upon liquidation, dissolution or
      winding up of the Company over any other class of stock of the Company,
      (ii) not subject to redemption in the
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      Charter or (iii) issued to the holders of Common Stock upon any
      reclassification thereof.

            Demand Registration means any request by the Stockholders to
      register the Registrable Securities pursuant to Section 3(a)(i).

            indemnified party and indemnifying party.  As defined in
      Section 9(c).

            Instrument of Accession means an Instrument of Accession in the form
      of Exhibit A hereto.

            Piggyback Registration.  As defined in Section 4(a)(i).

            Public Sale means any sale of Registrable Securities to the public
      pursuant to a public offering registered under the Securities Act or to
      the public through a broker or marketmaker pursuant to the provisions of
      Rule 144 (or any successor rule) adopted under the Securities Act or any
      other public offering not required to be registered under the Securities
      Act.

            Qualified Public Offering has the meaning assigned to the term
      "Qualified Public Offering" in the Charter.

            Registration Expenses.  As defined in Section 8(a).

            registered and registration mean a registration effected by
      preparing and filing a registration statement in compliance with the
      Securities Act and the declaration or ordering by the Commission of the
      effectiveness of such registration statement.

            Registrable Securities means at any particular time all shares of
      Common Stock (a) into which the Series B Preferred Stock, the Series C
      Preferred Stock and the Series D Preferred Stock have been converted and
      (b) acquired after the date hereof by any Series B Investor, Series C
      Investor or Series D Investor, including shares of Common Stock issuable
      on the conversion of other securities or other options, that have not been
      sold in a Public Sale, less those shares held by Stockholders whose entire
      holdings of such shares are eligible for resale, without registration,
      under Rule 144 in any three (3) month period.

            Rule 144 means Rule 144 adopted by the Commission under the
      Securities Act, as such rule may be amended from time to time, or any
      similar rule or regulation hereafter adopted by the Commission.

            Securities Act means the Securities Act of 1933, as amended, or any
      successor federal statute, and the rules and regulations of the Commission
      promulgated thereunder, all as the same shall be in effect from time to
      time.
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            Series B Preferred Stock means the Series B Convertible Preferred
      Stock, $.01 par value per share, of the Company.

            Series C Preferred Stock means the Series C Convertible Preferred
      Stock, $.01 par value per share, of the Company.

            Series D Preferred Stock means the Series D Convertible Preferred
      Stock, $.01 par value per share, of the Company.

            Stockholders means, initially, the Investors and, thereafter, any
      Person who becomes a party to this Agreement by executing an Instrument of
      Accession in connection with a transfer to or acquisition by such Person
      or Persons who become holders of Registrable Securities pursuant to or in
      connection with a transfer permitted under Section 13(e) herein from any
      Investor or any subsequent transferee of an Investor; provided, that the
      term "Stockholder" shall not include any Person who has sold, transferred
      or otherwise disposed of all of such Person's Registrable Securities.

            Underwriters' Maximum Number means, for any Piggyback Registration,
      Demand Registration or other registration which is an underwritten
      registration, that number of securities to which such registration should,
      in the opinion of the managing underwriters of such registration in the
      light of marketing factors, be limited.

      3.    Stockholder Demand Registration.

            (a)   Request for Demand Registration.

                  (i) Subject to the limitations contained in the following
      paragraphs of this Section 3, the holders of thirty-three percent (33%) or
      more of the Registrable Securities then outstanding may at any time on or
      after 180 days after the effective date of the registration statement of
      the Company's Qualified Public Offering, give to the Company, pursuant to
      this clause (i), a written request to register the Registrable Securities.
      Within ten (10) days after the receipt by the Company of any such written
      request, the Company will give written notice of such registration request
      to all Stockholders.

                  (ii) Subject to the limitations contained in the following
      paragraphs of this Section 3, after the receipt of such written request
      for a Demand Registration, (A) the Company will be obligated and required
      to include in such Demand Registration all Registrable Securities with
      respect to which the Company shall receive from Stockholders, within
      thirty (30) days after the date on which the Company shall have given to
      all Stockholders a written notice of registration request pursuant to
      Section 3(a)(i) hereof, the written requests of such
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      Stockholders for inclusion of their respective shares of Registrable
      Securities in such Demand Registration, and (B) the Company will use its
      best efforts to prepare and file with the Commission a registration
      statement under the Securities Act on any appropriate form promulgated by
      the Commission and reasonably acceptable to the Stockholders requesting
      such Demand Registration pursuant to clause (i) above covering all such
      Registrable Securities and shall use its best efforts to cause such
      registration statement to become effective under the Securities Act. All
      written requests made by Stockholders pursuant to this clause (ii) will
      specify the number of shares of Registrable Securities to be registered
      and will also specify the intended method of disposition thereof. Such
      method of disposition shall, in any case, be an underwritten offering if
      an underwritten offering is requested by the Demanding Stockholders (as
      defined in Section 3(c) hereof) holding fifty-one percent (51%) or more of
      the Registrable Securities to be included in such Demand Registration by
      all of the Demanding Stockholders.

                  (iii) The Stockholders shall be permitted to withdraw all or
      any part of the Registrable Securities of such Stockholders from any
      Demand Registration at any time prior to the effective date of such Demand
      Registration but, in the case of an underwritten public offering, only if
      such Stockholders are permitted to do so by the managing underwriters or
      pursuant to any agreement therewith.

            (b)   Limitations on Demand Registration.

                  (i) The holders of Series B Preferred Stock, the holders of
      Series C Preferred Stock and the holders of Series D Preferred Stock shall
      not be entitled to require the Company to effect, pursuant to Section 3(a)
      hereof, more than two (2) Demand Registrations but shall be entitled to
      unlimited additional Demand Registrations if such additional Demand
      Registrations would be eligible for registration on Form S-3 (after the
      Company qualifies for Form S-3, provided that in the case of any
      individual such Demand Registration the aggregate gross proceeds from such
      S-3 Demand Registration would exceed $500,000, if all registered shares
      thereunder were sold) provided, however, that there shall be no more than
      two (2) such registrations in any twelve (12) month period.

                  (ii) Any registration initiated pursuant to Section 3(a)
      hereof shall not count as a Demand Registration for purposes of Section
      3(a) hereof unless and until such registration shall have become effective
      and seventy-five percent (75%) of the number of shares initially included
      in the first filing by the Company with the Commission, but not withdrawn
      under Section 3(a)(iii) above, shall have been actually sold (unless the
      requesting Stockholders withdraw all their Registrable Securities and the
      Company has performed its obligations hereunder in all material respects,
      in which case such demand will count as a Demand Registration unless the
      requesting Stockholders pay all Registration Expenses in connection with
      the withdrawn registration).
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                  (iii) The Company shall not be obligated or required to effect
      the Demand Registration of any Registrable Securities pursuant to Section
      3(a) hereof during (a) the period commencing on the date falling
      forty-five (45) days prior to the Company's estimated date of filing (as
      notified to the Stockholders in writing) of, and ending on the date 180
      days following the effective date of, any registration statement
      pertaining to any firm commitment underwritten registration of the
      Company's equity securities or such shorter period which in the opinion of
      the managing underwriters), if any, of such registration would not affect
      the marketability of the shares being offered thereby (x) initiated by the
      Company, and solely for the account of the Company (other than any
      registration by the Company on Form S-8 or similar form or dividend
      reinvestment plan) or (y) initiated pursuant to Section 3(a)(i) hereof or
      (b) the ninety (90) day period after the commencement by the Company of
      any activity (a "Material Activity") that, in the good faith business
      judgment of the Company's Board of Directors, would be materially and
      adversely affected to the detriment of the Company by the requested Demand
      Registration (provided that (x) the Demand Registration may only be
      deferred if the Material Activity was commenced prior to receipt by the
      Company of the request for the Demand Registration, and (y) no more than
      one (1) deferral may be effected pursuant to clause (a) or (b) during any
      360 day period). A deferral of a Demand Registration pursuant to this
      Section 3(b)(iii) shall be lifted, and, unless the Demand Registration
      request has been withdrawn as contemplated below, the requested
      registration statement shall be filed forthwith, if, in the case of a
      deferral pursuant to clause (a) of the preceding sentence, the proposed
      registration for the Company's account is abandoned or not declared
      effective within ninety (90) days from the filing date, or in the case of
      a deferral pursuant to clause (b) of the preceding sentence, the Company
      ceases to be engaged in a Material Activity (and the Board of Directors
      shall immediately notify the Stockholders if, in their good faith
      determination, such activity has ceased). In order to defer the filing of
      a registration statement pursuant to this Section 3(b)(iii), the Company
      shall promptly (but in any event within ten (10) days), upon determining
      to effect such deferral, deliver to each Stockholder a certificate signed
      by an executive officer of the Company, on behalf of the Board of
      Directors, stating that the Company is deferring such filing pursuant to
      this Section 3(b)(iii) and setting forth the anticipated deferral period.
      Within twenty (20) days after receiving such certificate, the holders of a
      majority of the Registrable Securities owned by the Stockholders and for
      which registration was previously requested may withdraw such Demand
      Registration request by giving notice to the Company; if withdrawn, the
      Demand Registration request shall be deemed not to have been made for all
      purposes of this Agreement. If any deferral is lifted as provided above,
      prompt notice thereof shall be given in writing to the Stockholders
      requesting Demand Registration who thereafter shall be entitled to deliver
      a new request. This Section 3(b)(iii) shall not prohibit the Stockholders
      from exercising any "piggyback" registration rights to which they would
      otherwise be entitled pursuant to Section 4. The Company shall not be
      required to
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      maintain the effectiveness of any Demand Registration beyond the earlier
      to occur of (i) the consummation of the distribution by Stockholders of
      the Registrable Securities included therein or (ii) 180 days after the
      effective date thereof, unless such registration is a "shelf registration"
      in which case the Company will be required to maintain such effectiveness
      until the earlier to occur of (i) 365 days from the effectiveness thereof
      or (ii) the date on which the last security registered thereunder is sold.

            (c) Priority on Demand Registrations. If the managing underwriters
in any Demand Registration pursuant to this Section 3 shall give written advice
to the Company and the Stockholders that, in their opinion, there is an
Underwriters' Maximum Number of shares of Registrable Securities that may
successfully be included in such registration, then: (i) if the Underwriters'
Maximum Number is less than the number of shares of Registrable Securities
requested to be included in such registration, the Company will be obligated and
required to include in such registration that number of shares of Registrable
Securities which does not exceed the Underwriters' Maximum Number, and such
number of shares of Registrable Securities shall be allocated (A) first, pro
rata among the Stockholders of the class or classes of securities which
initiated the Demand Registration pursuant to this Section 3 (such Stockholders
being referred to herein as the "Demanding Stockholders") on the basis of the
number of shares of Registrable Securities requested to be included therein by
each such Demanding Stockholder, up to the Underwriters' Maximum Number, before
any other securities are included therein, and (B) next, pro rata among the
Stockholders (other than the Demanding Stockholders) on the basis of the number
of shares of Registrable Securities requested to be included therein by each
such Stockholder, up to the number of securities which they requested to include
in such registration which does not exceed the difference between the
Underwriters' Maximum Number and that number of securities included in such
registration pursuant to clause (A) of this sentence; and (ii) if the
Underwriters' Maximum Number exceeds the number of shares of Registrable
Securities requested to be included in such registration, then the Company will
be entitled to include in such registration that number of securities which
shall have been requested by the Company or by other securityholders of the
Company to be included in such registration for the account of the Company or
such other securityholders and which shall not be greater than such excess.
Neither the Company nor any of its securityholders shall be entitled to include
any securities in any underwritten Demand Registration unless the Company or
such securityholders (as the case may be) shall have agreed to such inclusion
and unless the Company and such other securityholders shall have agreed in
writing to sell such securities on the same terms and conditions as shall apply
to the Registrable Securities to be included in such Demand Registration.

            (d) Selection of Underwriters. If any Demand Registration or any
registration effected pursuant to Section 3 hereof is a firm commitment
underwritten offering, or a best efforts underwritten offering, the investment
bankers and managing underwriters in such registration will be selected by the
Company, subject to the approval of the Demanding Stockholders holding fifty-one
percent (51%) or more of the Registrable Securities to be included in such
registration by all of the Demanding Stockholders (which approval shall not be
unreasonably withheld).
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      4.    Piggyback Registrations.

            (a)   Rights to Piggyback.

                  (i) If (and on each occasion that) the Company proposes to
      register any of its equity securities or any other securities convertible
      into equity securities under the Securities Act for its own account or for
      the account of any other Person (other than pursuant to Section 3(a)
      hereof) (each such registration not withdrawn or abandoned prior to the
      effective date thereof being herein called a "Piggyback Registration"),
      the Company will give written notice to all Stockholders of such proposal
      not later than twenty (20) days prior to the anticipated filing date of
      such Piggyback Registration.

                  (ii) Subject to the provisions contained in paragraphs (b) and
      (c) of this Section 4 and in the last two sentences of this clause (ii),
      (A) the Company will be obligated and required to include in each
      Piggyback Registration all Registrable Securities with respect to which
      the Company shall receive from Stockholders, within thirty (30) days after
      the date on which the Company shall have given written notice of such
      Piggyback Registration to all Stockholders pursuant to Section 4(a)(i)
      hereof, the written requests of such Stockholders for inclusion in such
      Piggyback Registration, and (B) the Company will use its best efforts to
      promptly file with the Commission a registration statement under the
      Securities Act covering all such Registrable Securities and shall use its
      best efforts to cause such registration statement to become effective
      under the Securities Act. The Stockholders shall be permitted to withdraw
      all or any part of the Registrable Securities of such Stockholders from
      any Piggyback Registration at any time prior to the effective date of such
      Piggyback Registration but only in the case of an underwritten offering if
      such Stockholders are permitted to do so by the managing underwriters or
      pursuant to any agreement therewith. The Company will not be obligated or
      required to give notice of any proposed registration or include any
      Registrable Securities in any registration effected solely to implement an
      employee benefit plan or a transaction to which Rule 145 of the Commission
      is applicable. The Stockholders shall not be entitled to include
      Registrable Securities in a Piggyback Registration unless the Stockholders
      shall have agreed in writing to sell such securities on the same terms and
      conditions as shall apply to the securities (other than Registrable
      Securities) being included in such registration. The Company shall not be
      required to maintain the effectiveness of any Piggyback Registration
      beyond the earlier to occur of (i) the consummation of the distribution by
      holders of Registrable Securities included in such Piggyback Registration
      or (ii) 120 days after the effective date thereof.

            (b) Priority on Piggyback Registrations. If in connection with any
Piggyback Registration, the managing underwriters shall give written advice to
the Company that, in their opinion, there is an Underwriters' Maximum Number of
securities that may successfully be included in such registration, then: (i) the
Company shall be entitled to include in such

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registration that number of securities which the Company proposes to offer and
sell for its own account in such registration and which does not exceed the
Underwriters' Maximum Number; and (ii) the Company will be obligated and
required to include in such registration that number of shares of Registrable
Securities which shall have been requested by the Stockholders to be included in
such registration and which does not exceed the difference between the
Underwriters' Maximum Number and that number of securities which the Company is
entitled to include therein pursuant to clause (i) above and such number of
shares of Registrable Securities shall be allocated pro rata among each such
Stockholder, on the basis of the number of shares of Registrable Securities
requested to be included therein by each such Stockholder and, if the total of
such Registrable Securities and such securities which the Company is entitled to
include pursuant to clause (i) above is less than the Underwriters' Maximum
Number, the Company may include shares requested to be included by other
securityholders of the Company.

            (c) Selection of Underwriters. In any Piggyback Registration, the
Company shall (unless the Company shall otherwise agree) have the right to
select the investment bankers and managing underwriters in such registration.

      5.    Lockup Agreement.

            (a)   Restrictions on Public Sale by Stockholders.

                  (i) Each Stockholder, if the Company or the managing
      underwriters so request in connection with the initial registration of the
      Company's securities, will not, without the prior written consent of the
      Company or such underwriters, effect any public sale or other distribution
      of any equity securities of the Company, including any sale pursuant to
      Rule 144, during the period required by the managing underwriters;
      provided, however, that such period of time shall not exceed that
      applicable to all the Company's executive officers and directors.

                  (ii) If the Company or the managing underwriters so request,
      each Stockholder who holds 3% or greater of the Company's outstanding
      equity securities at the time of any registration, other than the
      Company's initial registration, or such lesser percentage if so determined
      by the managing underwriters, will not, without the prior written consent
      of the Company or such underwriters, effect any public sale or other
      distribution of any equity securities of the Company, including any sale
      pursuant to Rule 144, during the period required by the managing
      underwriters; provided, however, that such period of time shall not exceed
      that applicable to all the Company's executive officers and directors.

            (b) Restrictions on Public Sale by the Company. The Company agrees,
unless it obtains the consent of the managing underwriter(s) of any underwritten
offering of Registrable Securities pursuant to Sections 3 or 4 hereof, not to
effect any public sale or distribution of its equity securities, or any
securities convertible into or exchangeable or exercisable for such equity
securities, during the period commencing on the seventh day prior to, and ending
on the ninetieth
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                                      -9-


day (or such longer period as shall be reasonably required by the managing
underwriters) following, the effective date of any underwritten Demand or
Piggyback Registration, except in connection with any such underwritten
registration, or pursuant to any registration statements on Form S-8 or the then
equivalent form.

      6. Registration Procedures. If (and on each occasion that) the Company
shall become obligated to effect any registration of any Registrable Securities
hereunder, the Company will use its best efforts to effect promptly the
registration of such Registrable Securities under the Securities Act and to
permit the public offering and sale of such Registrable Securities in accordance
with the intended method of disposition thereof, and, in connection therewith,
the Company, as expeditiously as shall be reasonably possible, shall:

            (a) use its best efforts to prepare and file with the Commission a
registration statement with respect to such Registrable Securities, and use its
best efforts to cause such registration statement to become and remain effective
as provided herein;

            (b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus including such
registration statement as may be necessary or advisable to comply in all
material respects with the provisions of the Securities Act with respect to the
disposition of all securities covered by such registration statement or as may
be necessary to keep such registration statement effective and current as
provided herein;

            (c) furnish to each seller of Registrable Securities such number of
copies of such registration statement, each amendment and supplement thereto (in
each case including all exhibits thereto), the prospectus included in such
registration statement (including each preliminary prospectus), and such other
documents as any such seller may reasonably request in order to facilitate the
disposition of the Registrable Securities held by such seller;

            (d) use its best efforts to register and qualify the Registrable
Securities covered by such registration statement under such securities or blue
sky laws of such jurisdictions as any seller (or the managing underwriter, in
the case of any underwritten offering) shall reasonably request and do any and
all such other acts and things as may be reasonably necessary or advisable to
permit the disposition in such jurisdictions of the Registrable Securities
covered by such registration statement; provided, however, that the Company
shall not be required in connection therewith to qualify to do business or file
a general consent to service of process in any such jurisdiction, unless the
Company is already subject to service in such jurisdiction or subject itself to
taxation in any jurisdiction where the Company is not already subject to
taxation;

            (e) furnish to each prospective seller a signed counterpart,
addressed to the prospective sellers, (or to the underwriters, in the case of
any underwritten offering) of (i) an opinion of counsel for the Company, dated
the effective date of the registration statement, and (ii) to the extent not
prohibited by applicable financial accounting statements or standards not
generally delivered by "big six" accounting firms, a "comfort" letter signed by
the independent public accountants who have certified the Company's financial
statements included in the
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                                      -10-


registration statement, covering substantially the same matters with respect to
the registration statement (and the prospectus included therein) and (in the
case of the "comfort" letter) with respect to events subsequent to the date of
the financial statements, as are customarily covered (at the time of such
registration) in opinions of issuer's counsel and in "comfort" letters,
respectively, delivered to the underwriters in underwritten public offerings of
securities.

      7. Cooperation by Prospective Sellers, etc.

            (a) Each prospective seller of Registrable Securities will furnish
to the Company in writing such information as the Company may reasonably require
and which is customary in such transactions from such seller, and otherwise
reasonably cooperate with the Company in connection with any registration
statement with respect to such Registrable Securities.

            (b) The failure of any prospective seller of Registrable Securities
to furnish any information or documents in accordance with any provision
contained in this Agreement shall not affect the obligations of the Company
under this Agreement to any remaining sellers who furnish such information and
documents unless in the reasonable opinion of counsel to the Company or the
underwriters, such failure impairs or may impair the viability of the offering
or the legality of the registration statement or the underlying offering.

            (c) The Stockholders included in any registration statement will not
(until further notice) affect sales of Registrable Securities included in any
registration statement after receipt of telegraphic or written notice from the
Company to suspend sales to permit the Company to correct or update such
registration statement or prospectus (which obligation to correct or update the
Company will satisfy promptly); but the obligations of the Company with respect
to maintaining any registration statement current and effective shall be
extended by a period of days equal to the period such suspension is in effect.

            (d) At the end of any period during which the Company is obligated
to keep any registration statement current and effective as provided herein (and
any extensions thereof required by the preceding paragraph (c) of this Section
7), the Stockholders included in such registration statement shall discontinue
sales of shares pursuant to such registration statement upon receipt of notice
from the Company of its intention to remove from registration the shares covered
by such registration statement which remain unsold, and such Stockholders shall
notify the Company of the number of shares registered which remain unsold
promptly after receipt of such notice from the Company.

      8.    Registration Expenses.

            (a) Except as otherwise provided herein, all fees and expenses
incurred or sustained in connection with or arising out of the Demand
Registrations pursuant to Section 3 hereof and each registration pursuant to
Section 4 hereof, including, without limitation, all registration, filing fees
and qualification fees, fees and expenses of compliance with federal and state
securities or blue sky laws (including reasonable fees and disbursements of
counsel for the
<PAGE>   11
                                      -11-


underwriters in connection with the blue sky qualification of Registrable
Securities), printing expenses, messenger, telephone, facsimile and delivery
expenses, fees and disbursements of counsel for the Company, reasonable fees and
disbursements of one counsel representing any or all of the selling holders of
Registrable Securities, fees and disbursements of all independent certified
public accountants of the Company (including the expenses relating to the
preparation and delivery of any special audit or "cold comfort" letters required
by or incident to such registration), and fees and disbursements of underwriters
(excluding discounts, commissions and expenses representing disguised
commissions), the reasonable fees and expenses of any special experts retained
by the Company of its own initiative or at the request of the managing
underwriters in connection with such registration, and fees and expenses of all
(if any) other persons retained by the Company (all such costs and expenses
being herein called, collectively, the "Registration Expenses"), will be borne
and paid by the Company. The Company will, in any case, pay its internal
expenses (including, without limitation, all salaries and expenses of its
officers and employees performing legal or accounting duties), the expense of
any annual audit, and the fees and expenses incurred in connection with the
listing of the securities to be registered on each securities exchange on which
similar securities of the Company are then listed.

            (b) The Company will not bear the cost of nor pay for any stock
transfer taxes imposed in respect of the transfer of any Registrable Securities
to any purchaser thereof by any Stockholder in connection with any registration
of Registrable Securities pursuant to this Agreement.

            (c) To the extent the Registration Expenses incident to any
registration are, under the terms of this Agreement, not required to be paid by
the Company, each Stockholder included in such registration will pay all
Registration Expenses which are solely attributable to the registration of such
Stockholder's Registrable Securities so included in such registration, and all
other Registration Expenses not so attributable to one Stockholder will be borne
and paid by all sellers of securities included in such registration in
proportion to the number of securities so included by each such seller.

      9.    Indemnification.

            (a) Indemnification by the Company. To the full extent permitted by
law, the Company will indemnify and hold harmless each Stockholder requesting or
joining in a registration and each underwriter of the securities so registered,
the officers, directors, agents, employees and partners of each such Person and
each Person, if any, who controls, is controlled by or is under common control
any thereof (within the meaning of the Securities Act) against any and all
claims, losses, damages and liabilities (or actions in respect thereof) arising
out of or based on any untrue statement (or alleged untrue statement) of any
material fact contained in any registration statement, prospectus or any
amendment or supplement thereto, or any document filed pursuant to state
securities laws (or in any related registration statement, notification or the
like) or any omission (or alleged omission) to state therein any material fact
required to be stated therein or necessary to make the statements therein not
misleading, or any violation or alleged violation by the Company of the
Securities Act or the Securities Exchange Act of 1934, as amended (the "1934
Act") or any rule or regulation promulgated under the Securities Act or the
<PAGE>   12
                                      -12-


1934 Act or state securities or "blue sky" laws, common law or otherwise
applicable to the Company and relating to any action or inaction required of the
Company in connection with any such registration, qualification or compliance,
and the Company will reimburse each such Stockholder, underwriter, and each
other Person indemnified pursuant to this paragraph (a) for any legal and any
other expenses reasonably incurred in connection with investigating or defending
any such claim, loss, damage, liability or action provided, however, that the
Company will not be liable in any such case to the extent that any such claim,
loss, damage, liability or expense arises out of or is based on any untrue
statement or omission (or alleged untrue statement or omission) made in reliance
upon and in conformity with written information furnished to the Company by such
Stockholder, underwriter, officer, director, partner or controlling person and
stated to be specifically for use therein and provided further, that such
indemnity shall not inure to the benefit of any Stockholder, underwriter,
director, partner or controlling person ("indemnifiable party") from whom the
person asserting any claim, loss, damage or expense purchased securities which
are the subject thereof if such indemnified party failed to send or give a copy
of the prospectus or such other document as amended or supplemented to such
person at or prior to the confirmation of the sale of such securities to such
person in any case where such delivery is required by the Securities Act by such
indemnified party and the untrue statement or omission of a material fact
contained in a preliminary prospectus was corrected in the prospectus as amended
and supplemented. The Company also agrees to indemnify and provide contribution
arrangements to any underwriters of the Registrable Securities, their officers
and directors and each person who controls such underwriters (within the meaning
of Section 15 of the Securities Act or Section 20 of the 1934 Act)
(collectively, "Securities Professionals") on substantially the same basis as
that of the indemnification of the Stockholder provided in this Section 9 and in
Section 10, if requested.

            (b) Indemnification by Each Stockholder. Each Stockholder requesting
or joining in a registration will severally, and not jointly, indemnify each
underwriter of the securities so registered, the Company and the officers,
agents, employees and directors of the Company and each Person, if any, who
controls any thereof (within the meaning of the Securities Act) and their
respective successors in title and assigns against any and all claims, losses,
damages and liabilities (or actions in respect thereof) arising out of or based
on any untrue statement (or alleged untrue statement) of any material fact
contained in any registration statement, prospectus, or any amendment or
supplement thereto, or any dominant filed pursuant to state securities laws (or
in any related registration statement, notification or the like) or any omission
(or alleged omission) to state therein any material fact required to be stated
therein or necessary to make the statements therein not misleading, or any
violation or alleged violation by such Stockholder of any rule or regulation
promulgated under the Securities Act or the 1934 Act applicable to such Person
and relating to any action or inaction required of such Person in connection
with any such registration, qualification or compliance, and such Stockholder
will reimburse each underwriter, the Company and each other Person indemnified
pursuant to this paragraph (b) for any legal and any other expenses reasonably
incurred in connection with investigating or defending any such claim, loss,
damage, liability or action; provided, however, that this paragraph (b) shall
apply only if (and only to the extent that) such statement or omission (or
alleged untrue statement or omission) was made in reliance upon and in
conformity with written information furnished to such underwriter or the Company
by any such Stockholder or
<PAGE>   13
                                      -13-


any officer, director, partner or controlling person of such Stockholder and
stated to be specifically for use therein, and provided further that each
Stockholder's liability hereunder (including, without limitation, Section 10)
with respect to any particular registration shall be limited to an amount equal
to the proceeds received by such Stockholder from the Registrable Securities
sold by such Stockholder in such registration. The Company and the Stockholders
shall be entitled to receive indemnities from underwriters participating in any
distribution of Registrable Securities to the same extent as provided above with
respect to information so furnished in writing by such underwriters expressly
for use in any prospectus or registration statement.

            (c) Indemnification Proceedings. Each party entitled to
indemnification pursuant to this Section 9 (the "indemnified party") shall give
notice to the party required, to provide indemnification pursuant to this
Section 9 (the "indemnifying party") promptly after such indemnified party
acquires actual knowledge of any claim as to which indemnity may be sought, and
shall permit the indemnifying party (at its expense) to assume the defense of
any claim or any litigation resulting therefrom; provided that counsel for the
indemnifying party, who shall conduct the defense of such claim or litigation,
shall be reasonably acceptable to the indemnified party, and the indemnified
party may participate in such defense at the indemnified party's expense; and
provided, further that the failure by any indemnified party to give notice as
provided in this paragraph (c) shall not relieve the indemnifying party of its
obligations under this Section 9, except to the extent the indemnifying party is
materially prejudiced by such failure. No indemnifying party, in the defense of
any such claim or litigation, shall, except with the consent of each indemnified
party, consent to entry of any judgment or enter into any settlement which does
not include as an unconditional term thereof the giving by the claimant or
plaintiff to such indemnified party of a release from all liability in respect
of such claim or litigation. The reimbursement required by this Section 9 shall
be made by periodic payments during the course of the investigation or defense,
as and when bills are received or expenses incurred.

      10. Contribution in Lieu of Indemnification. If the indemnification
provided for in Section 9 hereof is unavailable to a party that would have been
an indemnified party under any such section in respect of any losses, claims,
damages, expenses or liabilities (or actions in respect thereof) referred to
therein, then each party that would have been an indemnifying party thereunder
shall, in lieu of indemnifying such indemnified party, contribute to the amount
paid or payable by such indemnified party as a result of such losses, claims,
damages, expenses or liabilities (or actions in respect thereof) in such
proportion as is appropriate to reflect the relative fault of the indemnifying
party on the one hand and such indemnified party on the other in connection with
the statements or omissions which resulted in such losses, claims, damages,
expenses or liabilities (or actions in respect thereof). The relative fault
shall be determined by reference to, among other things, whether the untrue or
alleged untrue statement of a material fact or the omission or alleged omission
to state a material fact relates to information supplied by the indemnifying
party or such indemnified party and the parties' relative intent, knowledge,
access to information and opportunity to correct or prevent such statement or
omission. The Company and each Stockholder agree that it would not be just and
equitable if contribution pursuant to this Section 10 were determined by pro
rata allocation or by any other method of
<PAGE>   14
                                      -14-


allocation which does not take into account the equitable considerations
referred to above in this Section 10. The amount paid or payable by an
indemnified party as a result of the losses, claims, damages, expenses or
liabilities (or actions in respect thereof) referred to above in this Section 10
shall include any legal or other expenses reasonably incurred by such
indemnified party in connection with investigating or defending any such action
or claim. No Person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Securities Act) shall be entitled to indemnification or
contribution from any Person who was not guilty of such fraudulent
misrepresentation.

      11. Rule 144 Requirements; Current Public Information. From time to time
after the earlier to occur of (a) the ninetieth day following the date on which
there shall first become effective a registration statement filed by the Company
under the Securities Act with respect to its equity securities, or (b) the date
on which the Company shall register a class of equity securities under Section
12 of the 1934 Act, the Company will use its best efforts to file all reports
required to be filed by it under the Securities Act or the 1934 Act and the
rules and regulations adopted by the Commission thereunder, and will take such
further action as any holder of Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock or Registrable Securities may reasonably request
all to the extent required to enable each such holder to sell Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock or Registrable
Securities pursuant to Rule 144. The Company will furnish to any Stockholder,
upon request made by such Stockholder at any time after the undertaking of the
Company in the preceding sentence shall have first become effective, a written
statement signed by the Company, addressed to such Stockholder, describing
briefly the action the Company has taken or proposes to take to comply with the
current public information requirements of Rule 144. The Company will, at the
request of any Stockholder, upon receipt from such Stockholder of an unqualified
written opinion of counsel knowledgeable in securities law matters, addressed to
the Company and reasonably acceptable in form and substance to the Company and
its counsel, remove from the stock certificates representing such Registrable
Securities that portion of any restrictive legend which relates to the
registration provisions of the Securities Act, and, thereupon, such Registrable
Securities will cease to be Registrable Securities for purposes of this
Agreement.

      12. Participation in Underwritten Registrations. No person may participate
in any underwritten registration pursuant to this Agreement unless such person
(a) agrees to sell such person's securities on the basis provided in any
underwriting arrangements approved by the persons entitled, under the provisions
hereof, to approve such arrangements, and (b) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents reasonably required by the terms of such underwriting
arrangements. Any Stockholder to be included in any underwritten registration
shall be entitled at any time to withdraw such Registrable Securities from such
registration prior to the execution of the related underwriting agreement in the
event that such Stockholder shall disapprove of any of the terms of such
agreement.
<PAGE>   15
                                      -15-


      13.   Confidentiality and Non-Disclosure.

      (a) Disclosure of Terms. The terms and conditions of this Agreement, the
Stock Purchase Agreement, the Second Amended and Restated Co-Sale Agreement and
the Second Amended and Restated Voting Agreement (collectively, the "Financing
Terms"), including their existence, shall be considered confidential information
and shall not be disclosed by any party hereto to any third party except in
accordance with the provisions set forth below.

      (b) Press Releases, Etc. Within sixty (60) days of the Closing, the
Company may issue a press release disclosing that the Purchasers have invested
in the Company; provided that the release does not disclose any of the Financing
Terms and is approved in advance in writing by any Purchaser who is named in
such press release. Intel Corporation ("Intel") and any other Purchaser, at its
sole discretion, may provide an executive quote or other material regarding its
investment in the Company. No other announcement regarding any Purchaser or the
Company in a press release, conference, advertisement, announcement,
professional or trade publication, mass marketing materials or otherwise to the
general public may be made without such named party's prior written consent.

      (c) Permitted Disclosures. Notwithstanding the foregoing, (i) any party
may disclose any of the Financing Terms to its current or bona fide prospective
investors, partners of such investors, employees, investment bankers, lenders,
accountants and attorneys, in each case only where such persons or entities are
under appropriate nondisclosure obligations; (ii) any party may disclose (other
than in a press release or other public announcement described in subsection
(b)) solely the fact that the Purchasers are investors in the Company to any
third parties without the requirement for the consent of any other party or
nondisclosure obligations; and (iii) Intel may disclose its investment in the
Company and the Financing Terms to third parties or to the public at its sole
discretion and, if it does so, the other parties hereto shall have the right to
disclose to third parties any such information disclosed in a press release or
other public announcement by Intel.

      (d) Legally Compelled Disclosure. In the event that any party is requested
or becomes legally compelled (including without limitation, pursuant to
securities laws and regulations) to disclose the existence of the Financing
Documents or any of the terms hereof in contravention of the provisions of this
Section 13, such party (the "Disclosing Party") shall provide the other parties
(the "Non-Disclosing Parties") with prompt written notice of that fact so that
the appropriate party may seek (with the cooperation and reasonable efforts of
the other parties) a protective order, confidential treatment or other
appropriate remedy. In such event, the Disclosing Party shall furnish only that
portion of the information which is legally required and shall exercise
reasonable efforts to obtain reliable assurance that confidential treatment will
be accorded such information to the extent reasonably requested by any
Non-Disclosing Party.

      (e) Other Information. The provisions of this Section 13 shall be in
addition to, and not in substitution for, the provisions of any separate
nondisclosure agreement executed by any of the parties hereto with respect to
the transactions contemplated hereby. Additional disclosures and exchange of
confidential information between the Company and Intel (including without
limitation, any exchanges of information with any Intel Board Observer, as
defined in the Second
<PAGE>   16
                                      -16-


Amended and Restated Voting Agreement) shall be governed by the terms of the
Corporate Non-Disclosure Agreement No. 76093, dated August 13, 1998, executed by
the Company and Intel, and any Confidential Information Transmittal Records
("CITR") provided in connection therewith. The CITR that shall govern the
exchanges of confidential information with any Intel Board Observer shall be the
form attached hereto as Exhibit B.

      14.   Miscellaneous.

            (a) No Inconsistent Agreements. The Company hereby represents and
warrants that it is not a party to or bound in any manner under, and covenants
that it will not enter into at any time after the date hereof, any agreement or
contract (whether written or oral) with respect to any of its securities which
prevents the Company from complying in any respect with the registration rights
granted by the Company to the Stockholders hereunder.

            (b) Waivers. No waiver of any breach or default hereunder shall be
considered valid unless in writing and signed by party granting such waiver, and
no waiver shall be deemed a waiver of any subsequent breach or default of the
same or similar nature.

            (c) Term. The agreements of the Company contained in this Agreement
shall continue in full force and effect so long as any Stockholder holds any
Registrable Securities.

            (d) Notices. Unless otherwise provided, any notice required or
permitted under this Agreement shall be given in writing and shall be deemed
effectively given (i) upon personal delivery to the party to be notified, (ii)
when delivered by overnight courier or (iii) five (5) days after deposit with
the United States Post Office, by registered or certified mail, return receipt
requested, postage prepaid and addressed:

      (i) if to a Series B Investor, at such Series B Investor's address on the
      signature pages hereto with a copy to:

      Joel M. Simon, Esq.
      Paul, Hastings, Janofsky & Walker LLP
      31st Floor
      399 Park Avenue
      New York, NY 10022
      Fax No.: (212) 3194090

      (ii) if to a Series C Investor or a Series D Investor, at such Series C
      Investor's or Series D Investor's address on the signature pages hereto
      with a copy to:

      Edward A. Reilly, Jr., Esq.
      LeBoeuf, Lamb, Greene & MacRae LLP
      225 Asylum Street, 13th Floor
      Hartford, CT 06103
      Fax No.: (860) 292-3555
<PAGE>   17
                                      -17-


      (iii) if to the Company, at:

      Synchronicity, Inc.
      201 Forest Street
      Marlborough, MA 01752
      Attention:  Dennis R. Harmon
      Fax No.: (508) 485-7514

      with a copy to:
      Linda DeRenzo, Esq.
      Testa, Hurwitz & Thibeault, LLP
      High Street Tower
      125 High Street
      Boston, MA 02110
      Fax No.: (617) 248-7100

and thereafter at such other address, notice of which has been given in
accordance with the provisions of this Section 14(d).

            (e) Assignability; Successors and Assigns. The registration rights
granted to the Investors herein shall be assignable only (i) to an assignee or
transferee who, as a result of such assignment, holds at least ten percent (10%)
of the aggregate of the then outstanding shares of Series B Preferred Stock;
(ii) to an assignee or transferee who, as a result of such assignment, holds at
least ten percent (10%) of the aggregate of the then outstanding shares of
Series C Preferred Stock; (iii) to an assignee or transferee who, as a result of
such assignment, holds at least ten percent (10%) of the aggregate of the then
outstanding shares of Series D Preferred Stock; or (iv) as to assignments by an
Investor to another Investor. Such subsequent holders of Registrable Securities
shall agree to be bound by all of the terms and conditions of this Agreement by
executing an Instrument of Accession in the form set forth in attached Exhibit
A. Otherwise, this agreement shall not confer any rights, remedies, obligations
or liabilities upon any third party, except for an indemnified party under
Section 9 and Section 10.

            (f) Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all of which
taken together shall constitute one and the same instrument.

            (g) Headings. The section and subsection headings contained herein
are for convenience only and are not intended to define or limit the contents of
said sections and subsections.

            (h) Governing Law. This Agreement and all amendments hereof shall be
governed by and construed in accordance with the laws of the Commonwealth of
Massachusetts, disregarding any Massachusetts principles of choice or conflict
of laws that would otherwise provide for the application of the substantive laws
of another jurisdiction.
<PAGE>   18
                                      -18-


            (i) Severability. If any provision of this Agreement shall be held
to be illegal, invalid or unenforceable, such illegality, invalidity or
unenforceability shall attach only to such provision and shall not in any manner
affect or render illegal, invalid or unenforceable any other provision of this
Agreement, and this Agreement shall be carried out as if any such illegal,
invalid or unenforceable provision were not contained herein.

            (j) Specific Performance. Without limiting the rights of each party
hereto to pursue all other legal and equitable rights and remedies available to
such party to any other party's failure to perform its obligations under this
Agreement, each such party acknowledges and agrees that the remedy at law for
any failure to perform obligations hereunder would be inadequate and all such
parties shall be entitled to specific performance, injunctive relief or other
equitable remedies in the event of any such failure.

            (k) Entire Agreement. (i) This Agreement constitutes the entire
agreement of the parties with respect to the subject matter hereof and may not
be modified, amended or terminated (other than in accordance with its terms)
except by a written agreement specifically referring to this Agreement and
signed by the Company and each of the Investors.

                  (ii) To the extent any term or other provision of any
agreement, instrument or oral understanding by which any party hereto is bound
conflicts with this Agreement, this Agreement shall have precedence over such
conflicting term or provision.


                      [REST OF PAGE INTENTIONALLY LEFT BLANK.]
<PAGE>   19
                                      -19-


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

                                    COMPANY:

                                    SYNCHRONICITY, INC.

                                    By: /s/ Dennis R. Harmon
                                       -------------------------------
                                    Name:
                                    Title:
                                    Address:
                                    201 Forest Street
                                    Marlborough, MA 01752

                                    INVESTORS:

                                    CANAAN CAPITAL LIMITED PARTNERSHIP

                                    By:   Canaan Capital Management L.P.

                                    By:   Canaan Capital Partners L.P.


                                    By: /s/ James Furnivall
                                       -------------------------------
                                       Name:
                                       Title:
                                       Address: 105 Rowayton Ave.
                                                Rowayton, CT  06853
                                                Attn.:  James Furnivall

                                    CANAAN CAPITAL OFFSHORE LIMITED
                                    PARTNERSHIP, C.V.

                                    By:   Canaan Capital Management L.P.

                                    By:   Canaan Capital Partners L.P.



                                    By: /s/ James Furnivall
                                       -------------------------------
                                        Name:
                                        Title:
                                        Address:105 Rowayton Ave.
                                                Rowayton, CT  06853
                                                Attn.:  James Furnivall

[Signature Page to Second Amended and Restated Registration Rights Agreement]
<PAGE>   20
                                      -20-


                                    CANAAN S.B.I.C., L.P.

                                    By:   Canaan S.B.I.C. Partners L.P.


                                    By: /s/ James Furnivall
                                       ___________________________________
                                       Name:
                                       Title:
                                       Address: 105 Rowayton Ave.
                                                Rowayton, CT  06853
                                                Attn.:  James Furnivall

                                    CANAAN EQUITY, L.P.

                                    By:   Canaan Equity Partners L.L.C.


                                    By: /s/ James Furnivall
                                       ___________________________________
                                       Name:
                                       Title:
                                       Address: 105 Rowayton Ave.
                                                Rowayton, CT  06853
                                                Attn.:  James Furnivall

                                    WHEATLEY PARTNERS, L.P.

                                    By:   Wheatley Partners, LLC


                                    By: /s/ Seth Lieber
                                       ___________________________________
                                       Name:    Seth Lieber
                                       Title:   General Partner
                                       Address: 80 Cuttermill Road,
                                                Suite 311
                                                Great Neck, New York 11021
                                                Attn: Maureen Wilson


[Signature Page to Second Amended and Restated Registration Rights Agreement]
<PAGE>   21
                                      -21-


                                    WHEATLEY FOREIGN PARTNERS, L.P.

                                    By:   Wheatley Partners, LLC


                                    By:   /s/ Seth Lieber
                                       ___________________________________
                                       Name:    Seth Lieber
                                       Title:   General Partner
                                       Address: 80 Cuttermill Road,
                                                Suite 311
                                                Great Neck, New York 11021
                                                Attn: Maureen Wilson

                                    PIONEER CAPITAL CORPORATION


                                    By: /s/ Leigh Michl
                                       ___________________________________
                                       Name:    Leigh E. Michl
                                       Title:   Vice President
                                       Address: 60 State Street
                                                Boston, MA 02109

                                    PIONEER VENTURES LIMITED PARTNERSHIP II

                                    By:   Pioneer Ventures Management LP, its
                                          General Partner

                                    By:   Pioneer Management SBIC Corp., its
                                          General Partner


                                    By: /s/ Leigh Michl
                                       ___________________________________
                                       Name:    Leigh E. Michl
                                       Title:   Vice President
                                       Address: 60 State Street
                                                Boston, MA 02109

[Signature Page to Second Amended and Restated Registration Rights Agreement]
<PAGE>   22
                                      -22-


                                    SYNOPSYS, INC.


                                        /s/ Robert Dahlberg
                                    By: __________________________________
                                       Name:
                                       Title:
                                       Address:

                                    INTEL CORPORATION

                                        /s/ Diane Labrador
                                    By: __________________________________
                                       Name:
                                       Title:
                                       Address:


                                    /s/ Mark A. Ross
                                    ______________________________________
                                    Mark A. Ross
                                    Address:
                                    Rock Creek Court
                                    Redwood City, CA 94062


                                    /s/ David Spitzman
                                    ______________________________________
                                    David Spitzman
                                    Address:
                                    1 Cliff Avenue
                                    Newport, RI  02840


                                    /s/ Mark Barlow
                                    ______________________________________
                                    Mark Barlow
                                    Address:
                                    18 Hazard Street
                                    Newport, RI  02840


                                    /s/ Marek Skoskiewicz
                                    ______________________________________
                                    Marek Skoskiewicz
                                    Address:
                                    16-376 County Road N
                                    Napoleon, OH 43545

[Signature Page to Second Amended and Restated Registration Rights Agreement]
<PAGE>   23
                                      -23-


                                    /s/ Leigh Michl
                                    ______________________________________
                                    Leigh E. Michl
                                    Address:
                                    74 Cherry Brook Road
                                    Weston, MA 02493


[Signature Page to Second Amended and Restated Registration Rights Agreement]