SPECTRA PRECISION SUPPLEMENT TO THE TRIMBLE NAVIGATION
                        1988 EMPLOYEE STOCK PURCHASE PLAN

     The following  constitutes the Spectra Precision  Supplement to the Trimble
Navigation 1988 Employee Stock Purchase Plan:
1.   Purpose.  The purpose of the Spectra  Precision  Supplement  to the Trimble
     Navigation  1988 Employee  Stock  Purchase Plan is to set forth the special
     terms pursuant to which the employees of any  Subsidiary  which employs the
     employees  associated with the acquired  business of Spectra  Precision may
     participate in the Plan following the  acquisition of Spectra  Precision by
     the Company.  Except as specifically set forth below, all of the provisions
     of the Plan shall apply to the  participation  of Spectra  Employees in the
     Plan  following  the  acquisition  of  Spectra  Precision  by the  Company.
     Capitalized terms used in this Supplement shall have the meanings set forth
     in the Plan or as stated below.
2.   Definition  of  "Spectra   Precision   Employee".   For  purposes  of  this
     Supplement,  "Spectra Precision Employee" shall mean an Employee of Spectra
     Precision, Inc. or any of its wholly owned subsidiaries,  Spectra Precision
     SRL, Spectra Physics Holdings GmbH or any of its wholly owned  subsidiaries
     including  ZSP  Geodetic  Systems  GmbH,   Spectra  Precision  BV,  Spectra
     Precision SA, Spectra Precision Scandinavia AB, Spectra Precision of Canada
     Ltd., Spectra Precision Handelsges GmbH or Spectra Precision AB.
3.   Effective Date and Sunset Date. This Supplement shall become effective July
     1, 2000 or, if later,  upon the  completion of the  acquisition  of Spectra
     Precision by the Company.  This  Supplement  shall cease to be effective at
     midnight on December 31, 2000.
4.   Eligibility.  Each Spectra  Precision  Employee  who has been  continuously
     employed by Spectra  Precision  or the Company or its  Subsidiaries  for at
     least two  consecutive  months and is so  employed  on the first day of the
     Spectra  Precision  Offering Period specified in Section 5 below,  shall be
     eligible to participate in the Plan during the Spectra  Precision  Offering
     Period.  For  purposes  of  determining  an  individual's   eligibility  to
     participate  in the Plan,  employment  before and after the  acquisition of
     Spectra Precision by the Company shall be taken into account.
5.   Initial  Offering  Period.  The  initial  Offering  Period for the  Spectra
     Precision  Employees  shall  commence on August 1, 2000 and end on December
     31, 2000; provided,  however,  that if the acquisition of Spectra Precision
     has not been completed by August 1, 2000, the initial  Offering  Period for
     the Spectra  Precision  Employees shall begin on the first day of the month
     following the month in which the acquisition is completed.
6.   Participation and Enrollment.  The terms of Section 5(a) of the Plan to the
     contrary  notwithstanding,  a  Spectra  Precision  Employee  may  become  a
     participant  in the  Plan  for the  initial  Offering  Period  for  Spectra
     Precision Employees described in Section 5 of this Supplement,  by filing a
     subscription  agreement with the Company's Stock  Administration  Office at
     least five business days prior to August 1, 2000.
7.   Limitation on Purchase. The provisions of Section 7(a) of the Plan shall be
     applied to the  initial  Offering  Period for Spectra  Precision  Employees
     described in Section 5 of this  Supplement  by  substituting  "$10,416" for
     "$12,500" where it appears in Section 7(a) of the Plan.


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