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                                                                    EXHIBIT 4.16

[NBD LOGO] CREDIT AUTHORIZATION AGREEMENT

NBD BANK (the "Bank"), whose address is 611 Woodward Avenue, Detroit, Michigan
48226-3947, has approved the credit facilities listed below (collectively, the
"Credit Facilities," and individually, as designated below) to INTERFACE
SYSTEMS, INC. (the "Borrower"), whose address is 5855 Interface Drive, Ann
Arbor, MI 48103, subject to the terms and conditions set forth in this
agreement.

         CREDIT FACILITIES.

         UNCOMMITTED CREDIT AUTHORIZATIONS.  The Bank has approved the uncom-
              mitted credit authorizations listed below (collectively, the
              "Credit Authorizations," and individually, as designated below)
              subject to the terms and conditions of this agreement and the
              Bank's continuing satisfaction with the Borrower's financial
              status.  Disbursements un- der the Credit Authorizations are
              solely at the Bank's discretion. Any disbursement on one or more
              occasions shall not commit the Bank to  make any subsequent
              disbursement.

              A.  FACILITY A.  The Bank has approved an uncommitted Credit
                  Authorization to the Borrower in the principal sum not to
                  exceed $3,500,000 in the aggregate at any one time
                  outstanding ("Facility A").  Credit under Facility A shall be
                  in the form of disbursements evidenced by credits to the 
                  Borrower's account and shall be repayable as set forth in
                  a Master Demand Note executed concurrently (referred to in
                  this agreement both singularly and together with any other
                  promissory notes referenced in this Section 1 as the
                  "Notes").  The proceeds of Facility A shall be used for the
                  following purpose: working capital.  Facility A shall expire
                  on February 28, 1998 unless earlier withdrawn.


         TERM LOANS.  The Bank agrees to extend credit to the Borrower in the 
              form of term loan(s) (whether one or more, the "Term Loans") in
              the  principal sum(s) of $224,999.98, respectively, bearing
              interest and  payable as set Forth in the Term Note(s) executed
              concurrently (referred to in this agreement both singularly and 
              together with any other  promissory notes referenced in this
              Section 1 as the "Notes").  The  proceeds of the Term Loans
              shall be used for the following purpose:  refinance existing term
              loan maturing February 28, 2002.

         2.0  CONDITIONS PRECEDENT.

         2.1  CONDITIONS PRECEDENT TO INITIAL EXTENSION OF CREDIT.  Before the
              first extension of credit under this agreement, whether by
              disbursement of a loan, issuance of a letter of credit, or
              otherwise, the Borrower shall deliver to the Bank, in form and
              substance satisfactory to the Bank:


              A.  LOAN DOCUMENTS.  The Notes; the letter of credit applications
                  required by Section 1.2; the security agreements, financing
                  statements, and mortgages required by Section 5.1; the
                  guaranties required by Section 6.0; the subordination
                  agreements required by Section 7.0; and any other loan
                  documents which the Bank may reasonably require to give
                  effect to the transactions contemplated by this agreement;

              B.  EVIDENCE OF DUE ORGANIZATION AND GOOD STANDING.  Evidence
                  satisfactory to the Bank of the due organization and good  
                  standing of the Borrower and every other business entity that
                  is a party to this agreement or any other loan document
                  required by this agreement; and

              C.  EVIDENCE OF AUTHORITY TO ENTER INTO LOAN DOCUMENTS.  Evidence
                  satisfactory to the Bank that (i) each party to this
                  agreement or any other loan document required by this
                  agreement is authorized to enter into the transactions
                  contemplated by this agreement and the other loan documents,
                  and (ii) the person signing on behalf of each such party is 
                  authorized to do so.

         2.2  CONDITIONS PRECEDENT TO EACH EXTENSION OF CREDIT.   Before any 
              extension of credit under this agreement, whether by disbursement
              of a loan, issuance of a letter of credit, or otherwise, the 
              following  conditions shall have been satisfied:

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     A. REPRESENTATIONS.  The representations contained in Section 10
        shall be true on and as of the date of the extension of credit;

     B. NO EVENT OF ACCELERATION.  No event of acceleration shall have
        occurred and be continuing or would result from the extension of
        credit;

     C. CONTINUED SATISFACTION.  The Bank shall have remained satisfied
        with the Borrower's managerial and financial status;

     ADDITIONAL APPROVALS, OPINIONS, AND DOCUMENTS.  The Bank shall have
     received such other approvals, opinions and documents as it may reasonably
     request.

3.0  BORROWING BASE/ANNUAL PAY DOWN.

BORROWING BASE. Notwithstanding any other provision of this agreement, the
     aggregate principal amount outstanding at any one time under Facility A
     shall not exceed the lesser of the Borrowing Base or $3,500,000.
     Borrowing Base means:

     A.  75% of the Borrower's trade accounts receivable in which the Bank
         has a perfected, first priority security interest, excluding
         accounts more than 90 days past due from the date of invoice, accounts
         subject to offset or defense, government, bonded, affiliate and
         foreign accounts, accounts from trade debtors of which more than 50%
         of the aggregate amount owing from the trade debtor to the Borrower is
         more than 90 days past due, and accounts otherwise unacceptable to the
         Bank, plus

     Inventory of the Borrower in which the Bank has a perfected first priority
         security interest, valued at the lower of cost or market in the
         aggregate, as follows:

     (1) 30% of purchased parts inventory; and
     (2) 0% of work-in-process, service stock, and demos inventory; and
     (3) 30% of finished goods inventory.

4.0  FEES AND EXPENSES.

     4.1  FEES. Upon execution of this agreement, the Borrower shall pay the 
          Bank the following fees, all of which the Borrower acknowledges have 
          been earned by the Bank:  documentation fees of $1000.

     4.2  OUT-OF-POCKET EXPENSES. In addition to any fee set forth in Section 
          4.1 above, the Borrower shall reimburse the Bank for its out-of- 
          pocket expenses and reasonable attorney's fees (including the fees 
          of in-house counsel) allocated to the Credit Facilities.

5.0  SECURITY.

     5.1  Payment of the borrowings under the Credit Facilities shall be 
          secured by a first security interest and/or real estate mortgage, as 
          the case may be, covering the following property and all its 
          additions, substitutions, increments, proceeds and products, whether 
          now owned or later acquired ("Collateral")

          A. ACCOUNTS RECEIVABLE. All of the Borrower's accounts, chattel
             paper, general intangibles, instruments, and documents (as those
             terms are defined in the Michigan Uniform Commercial Code), rights
             to refunds of taxes paid at any time to any governmental entity,
             and any letters of credit and drafts under them given in support
             of the foregoing, wherever located. The Borrower shall deliver to
             the Bank executed security agreements and financing statements in
             form and substance satisfactory to the Bank.

          B. INVENTORY. All of the Borrower's inventory, wherever located. The
             Borrower shall deliver to the Bank executed security agreements
             and financing statements in form and substance satisfactory to the
             Bank.

          C. EQUIPMENT. All of the Borrower's equipment, wherever located. The
             Borrower shall deliver to the Bank executed





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             security agreements and financing statements in form and substance
             satisfactory to the Bank.

         D.  REAL ESTATE. The real property, including improvements, located at
             5855 Interface Drive, Ann Arbor, MI and 7232 Jackson Road, Ann
             Arbor, MI.  The Borrower shall deliver to the Bank an executed
             mortgage, ALTA mortgage title insurance policy without exceptions,
             mortgage survey certified to the Bank and, where applicable, an
             assignment of rents, subordinations of leases, and/or collateral
             assignments of land contracts, all in form and substance
             satisfactory to the Bank.

         E.  PLEDGE of  65.5% or 1,400,000 shares of common stock of Interface
             Systems International, Ltd.  

     5.2 No forbearance or extension of time granted any subsequent owner of 
         the Collateral shall release the Borrower from liability.

     5.3 ADDITIONAL COLLATERAL/SETOFF. To further secure payment of the 
         borrowings under the Credit Facilities and all of the
         Borrower's other liabilities to the Bank, the Borrower grants to the
         Bank a continuing security interest in: (i) all securities and other
         property of the Borrower in the custody, possession or control of the
         Bank (other than property held by the Bank solely in a fiduciary
         capacity) and (ii) all balances of deposit accounts of the Borrower
         with the Bank. The Bank shall have the right at any time to apply its
         own debt or liability to the Borrower, or to any other party liable
         for payment of the borrowings under the Credit Facilities, in whole or
         partial payment of such borrowings or other present or future
         liabilities, without any requirement of mutual maturity.

     5.4 CROSS LIEN. Any of the Borrower's other property in which the Bank has
         a security interest to secure payment of any other debt,
         whether absolute, contingent, direct or indirect, including the
         Borrower's guaranties of the debts of others, shall also secure
         payment of and be part of the Collateral for the Credit Facilities.

     6.0 GUARANTIES. Payment of the Borrower's liabilities under the Credit
         Facilities shall be guaranteed by I.G.K. Industries, Inc., by
         execution of the Bank's form of guaranty agreement. The liability of
         the guarantors, if more than one, shall be joint and several.

7.0  SUBORDINATION. The Credit Facilities shall be supported by the
         subordination of all debt owing from the Borrower to n/a,
         including without limitation debt currently owing in the amount of
         $N/A, in manner and by agreement satisfactory to the Bank.

     8.0 AFFIRMATIVE COVENANTS. So long as any debt remains outstanding under 
         the Credit Facilities, the Borrower, and each of its subsidiaries, if 
         any, shall:

     8.1 INSURANCE. Maintain insurance with financially sound and reputable
         insurers covering its properties and business against those
         casualties and contingencies and in the types and amounts as shall be
         in accordance with sound business and industry practices.

     8.2 EXISTENCE. Maintain its existence and business operations as presently
         in effect in accordance with all applicable laws and
         regulations, pay its debts and obligations when due under normal
         terms, and pay on or before their due date, all taxes, assessments,
         fees and other governmental monetary obligations, except as they may
         be contested in good faith if they have been properly reflected on its
         books and, at the Bank's request, adequate funds or security has been
         pledged to insure payment.

     8.3 FINANCIAL RECORDS. Maintain proper books and records of account, in
         accordance with generally accepted accounting principles where
         applicable, and consistent with financial statements previously
         submitted to the Bank. The Bank shall retain the right to inspect the
         Collateral and business records related to it at such times and at
         such intervals as the Bank may reasonably require.

     8.4 NOTICE. Give prompt notice to the Bank of the occurrence of (i) any 
         event of acceleration, and (ii) any other development,
         financial or otherwise, which would affect the Borrower's business,
         properties or affairs in a materially adverse manner.

     8.5 COLLATERAL AUDITS.  Permit the Bank or its agents to perform
         audits of the Collateral. The Borrower shall compensate the
         Bank for such audits in  accordance with the Bank's schedule of fees
         as may be amended from time to time. Whether or





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          not this section has been completed, the Bank shall retain the
          right to inspect the Collateral and business records related to it at
          such times and at such intervals as the Bank may reasonably require.

     8.6  FINANCIAL REPORTS. Furnish to the Bank whatever information, books, 
          and records the Bank may reasonably request, including at a minimum: 
          If the Borrower has subsidiaries, all financial statements required   
          will be provided on a consolidated and on a separate basis.


          Within 30 days after each monthly period, a consolidating balance 
              sheet as of the end of that period and statements of income,
              cash flows, and retained earnings from the beginning of that
              fiscal year to the end of that period, certified as correct by
              one of its authorized agents.

          B.  Within 45 days after each quarterly period, a 10-Q financial
              report as of the end of that period.

          C.  Within 90 days after, and as of the end of, each of its fiscal
              years, a detailed audit of the Borrower and Interface Systems     
              International, Ltd., including a balance sheet and statements of
              income, retained earnings, and cash flows certified by an
              independent certified public accountant of recognized standing.

          D.  Within 30 days after and as of the end of each calendar
              month, the following lists, each certified as correct by one of   
              its authorized agents:

             (1) a list of accounts receivable, aged from date of invoice
              of the Borrower and Interface Systems International, Ltd.;
          
             (2) a list of accounts payable, aged from date of receipt of the 
              Borrower;

          E.  Within 30 days after, and as of the end of, each monthly period,
              a borrowing base exhibit indicating compliance with Section 3.1
              of the Borrower, and including Interface Systems International,
              LTD's compliance with its borrowing base requirements of its
              borrowings and contingent obligations under First Chicago issued
              bank guarantees limited to the lesser of GBP 5,200,000 or the sum
              of the following borrowing base of: (i) 75% of accounts
              receivable not over 90 days past due and excluding core business
              receivables of the Electronic Document Delivery division of the
              Borrower and accounts from trade debtors of which more than 50%
              of the aggregate owing are more than 90 days past due and; (ii)
              50% of finished goods inventory.

9.0  NEGATIVE COVENANTS.

     9.1  DEFINITIONS. As used in this agreement, the following terms shall 
          have the following respective meanings:

          A. "Net Worth" means total assets less total liabilities.

     9.2  Unless otherwise noted, the financial requirements set forth in this
          section shall be computed in accordance with generally accepted 
          accounting principles applied on a basis consistent with financial 
          statements previously submitted  by the Borrower to the Bank.

     Without the written consent of the Bank, so long as any debt remains
          outstanding under the Credit Facilities, the Borrower shall not:
          (where appropriate, covenants apply on a consolidated basis)

          A.  DIVIDENDS.  Acquire or retire any of its shares of capital stock,
              or declare or pay dividends or make any other distributions upon
              any of its shares of capital stock, except dividends payable in
              its capital stock and dividends payable to "Subchapter S"
              corporation shareholders in amounts sufficient in amount to pay
              the shareholders' income tax obligations related to the Borrower's
              taxable income.

          B.  SALE OF SHARES. Issue, sell or otherwise dispose of any shares of
              its capital stock or other securities, or rights, warrants or
              options to purchase or acquire any such shares or securities.





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         C.  DEBT. Incur, or permit to remain outstanding, debt for borrowed
             money or installment obligations, except debt reflected in the
             latest financial statement of the Borrower furnished to the Bank
             prior to execution of this agreement and not to be paid with
             proceeds of borrowings under the Credit Facilities. For purposes
             of this covenant, the sale of any accounts receivable shall be
             deemed the incurring of debt for borrowed money.

         D.  GUARANTIES. Guarantee or otherwise become or remain secondarily
             liable on the undertaking of another, except for endorsement of
             drafts for deposit and collection in the ordinary course of
             business.

         E.  LIENS. Create or permit to exist any lien on any of its property,
             real or personal, except: existing liens known to the Bank; liens
             to the Bank; liens incurred in the ordinary course of business
             securing current nondelinquent liabilities for taxes, worker's
             compensation, unemployment insurance, social security and pension
             liabilities; and liens for taxes being contested in good faith.

         F.  ADVANCES AND INVESTMENTS. Purchase or acquire any securities of,
             or make any loans or advances to, or investments in, any person,
             firm or corporation, except advances to Interface Systems
             International, Ltd. and obligations of the United States
             Government, open market commercial paper rated one of the top two
             ratings by a rating agency of recognized standing, or certificates
             of deposit in insured financial institutions.

         G.  USE OF PROCEEDS.  Use, or permit any proceeds of the Credit
             Facilities to be used, directly or indirectly, for the purpose of
             "purchasing or carrying any margin stock" within the meaning of
             Federal Reserve Board Regulation U.  At the Bank's request, the
             Borrower shall furnish to the Bank a completed Federal Reserve
             Board Form U-1.

         H.  NET WORTH.   Permit its Net Worth to be less than $10,300,000 at
             September 30, 1997 and thereafter increasing by 75% of monthly net
             income, without reduction for any loss periods.

  10.0   REPRESENTATIONS BY BORROWER. Each Borrower represents that: (a)
         the execution and delivery of this agreement and the Notes and
         the performance of the obligations they impose do not violate any law,
         conflict with any agreement by which the Borrower is bound, or require
         the consent or approval of any governmental authority or other third
         party; (b) this agreement and the Notes are valid and binding
         agreements, enforceable in accordance with their terms; and (c) all
         balance sheets, profit and loss statements, and other financial
         statements furnished to the Bank are accurate and fairly reflect the
         financial condition of the organizations and persons to which they
         apply on their effective dates, including contingent liabilities of
         every type, which financial condition has not changed materially and
         adversely since those dates.  Each Borrower, if other than a natural
         person, further represents that: (a) it is duly organized, existing
         and in good standing under the laws of the jurisdiction under which it
         was organized; and (b) the execution and delivery of this agreement
         and the Notes and the performance of the obligations they impose (i)
         are within its powers; (ii) have been duly authorized by all necessary
         action of its governing body; and (iii) do not contravene the terms of
         its articles of incorporation or organization, its bylaws, or any
         partnership, operating or other agreement governing its affairs.

11.0     ACCELERATION.

  11.1   EVENTS OF ACCELERATION. If any of the following events occurs, the
         Credit Facilities shall terminate and all borrowings under them shall 
         be due immediately, without notice, at the Bank's option, whether or 
         not the Bank has made demand.

         A.  The Borrower or any guarantor of any of the Credit Facilities or
             the Notes ("Guarantor") fails to pay when due  any amount payable
             under the Credit Facilities or under any agreement or instrument
             evidencing debt to any creditor;
         B.  The Borrower or any Guarantor (a) fails to observe or perform any
             other term of this agreement or the Notes; (b) makes any
             materially incorrect or misleading representation, warranty, or
             certificate to the Bank; (c) makes any materially incorrect or
             misleading representation in any financial statement or other
             information delivered to the Bank; or (d) defaults under the terms
             of any agreement or instrument relating to any debt for borrowed
             money (other than borrowings under the Credit Facilities) such
             that the creditor declares the debt due before its maturity;
         C.  There is a default under the terms of any loan agreement,
             mortgage, security agreement or any other document executed as
             part of the Credit Facilities, or any guaranty of the borrowings
             under the Credit Facilities becomes unenforceable in whole or in
             part, or any Guarantor fails to promptly perform under its
             guaranty;
         D.  A "reportable event" (as defined in the Employee Retirement Income
             Security Act of 1974 as amended) occurs that





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             would permit the Pension Benefit Guaranty Corporation to
             terminate any employee benefit plan of the Borrower or any
             affiliate of the Borrower;
         E.  The Borrower or any Guarantor becomes insolvent or unable to pay 
             its debts as they become due;
         F.  The Borrower or any Guarantor (a) makes an assignment for the
             benefit of creditors; (b) consents to the appointment of a
             custodian, receiver or trustee for it or for a substantial part of
             its assets; or (c) commences any proceeding under any bankruptcy,
             reorganization, liquidation or similar laws of any jurisdiction;
         G.  A custodian, receiver or trustee is appointed for the Borrower or
             any Guarantor or for a substantial part of its assets without its
             consent and is not removed within 60 days after such appointment;
         H.  Proceedings are commenced against the Borrower or any Guarantor
             under any bankruptcy, reorganization, liquidation, or similar laws
             of any jurisdiction, and such proceedings remain undismissed for
             60 days after commencement; or the Borrower or Guarantor consents
             to the commencement of such proceedings;
         I.  Any judgment is entered against the Borrower or any Guarantor, or
             any attachment, levy or garnishment is issued against any property
             of the Borrower or any Guarantor;
         J.  The Borrower or any Guarantor dies;
         K.  The Borrower or any Guarantor, without the Bank's written consent,
             (a) is dissolved, (b) merges or consolidates with any third party,
             (c) leases, sells or otherwise conveys a material part of its
             assets or business outside the ordinary course of business, (d)
             leases, purchases, or otherwise acquires a material part of the
             assets of any other corporation or business entity, except in the
             ordinary course of business, or (e) agrees to do any of the
             foregoing, (notwithstanding the foregoing, any subsidiary may
             merge or consolidate with any other subsidiary, or with the
             Borrower, so long as the Borrower is the survivor);
         L.  The loan-to-value ratio of any pledged securities at any time
             exceeds n/a%, and such excess continues for five (5) days after
             notice from the Bank to the Borrower;
         M.  There is a substantial change in the existing or prospective
             financial condition of the Borrower or any Guarantor which the
             Bank in good faith determines to be materially adverse; or
         N.  The Bank in good faith shall deem itself insecure.

  11.2   REMEDIES. If the borrowings under the Credit Facilities are not
         paid at maturity, whether by demand, acceleration or
         otherwise, the Bank shall have all of the rights and remedies provided
         by any law or agreement. Any requirement of reasonable notice shall be
         met if the Bank sends the notice to the Borrower at least seven (7)
         days prior to the date of sale, disposition or other event giving rise
         to the required notice. The Bank is authorized to cause all or any
         part of the Collateral to be transferred to or registered in its name
         or in the name of any other person, firm or corporation, with or
         without designation of the capacity of such nominee. The Borrower
         shall be liable for any deficiency remaining after disposition of any
         Collateral. The Borrower is liable to the Bank for all reasonable
         costs and expenses of every kind incurred in the making or collection
         of the Credit Facilities, including, without limitation, reasonable
         attorney's fees and court costs (whether attributable to the Bank's
         in-house or outside counsel). These costs and expenses shall include,
         without limitation, any costs or expenses incurred by the Bank in any
         bankruptcy, reorganization, insolvency or other similar proceeding.

12.0     MISCELLANEOUS.

  12.1   Notice from one party to another relating to this agreement shall
         be deemed effective if made in writing (including
         telecommunications) and delivered to the recipient's address, telex
         number or fax number set forth under its name below by any of the
         following means: (a) hand delivery, (b) registered or certified mail,
         postage prepaid, with return receipt requested, (c) first class or
         express mail, postage prepaid, (d) Federal Express, or like overnight
         courier service or (e) fax, telex or other wire transmission with
         request for assurance of receipt in a manner typical with respect to
         communication of that type. Notice made in accordance with this
         section shall be deemed delivered upon receipt if delivered by hand or
         wire transmission, 3 business days after mailing if mailed by first
         class, registered or certified mail, or one business day after mailing
         or deposit with an overnight courier service if delivered by express
         mail or overnight courier.

  12.2   No delay on the part of the Bank in the exercise of any right or
         remedy shall operate as a waiver. No single or partial exercise
         by the Bank of any right or remedy shall preclude any other future
         exercise of it or the exercise of any other right or remedy. No waiver
         or indulgence by the Bank of any default shall be effective unless in
         writing and signed by the Bank, nor shall a waiver on one occasion be
         construed as a bar to or waiver of that right on any future occasion.

  12.3   This agreement, the Notes, and any related loan documents embody
         the entire agreement and understanding between the Borrower and
         the Bank and supersede all prior agreements and understandings
         relating to their subject matter. If any one





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      or more of the obligations of the Borrower under this agreement or the
      Notes shall be invalid, illegal or unenforceable in any jurisdiction, the
      validity, legality and enforceability of the remaining obligations of the
      Borrower shall not in any way be affected or impaired, and such validity,
      illegality or unenforceability in one jurisdiction shall not affect the
      validity, legality or enforceability of the obligations of the Borrower
      under this agreement or the Notes in any other jurisdiction.

12.4  The Borrower, if more than one, shall be jointly and severally
      liable.

12.5  This agreement is delivered in the State of Michigan and governed
      by Michigan law. This agreement is binding on the Borrower and
      its successors, and shall inure to the benefit of the Bank, its
      successors and assigns.

12.6  Section headings are for convenience of reference only and shall
      not affect the interpretation of this agreement.

13.0  WAIVER OF JURY TRIAL:  The Bank and the Borrower knowingly and
      voluntarily waive any right either of them have to a trial by
      jury in any proceeding (whether sounding in contract or tort) which is
      in any way connected with this or any related agreement, or the
      relationship established under them.  This provision may only be
      modified in a written instrument executed by the Bank and the
      Borrower.



Effective Date:  August 31, 1997.



NBD BANK                                 BORROWER:
                                         Interface Systems, Inc.

By: _Mike Kelly______                    By: __John Ternes_______
                                         
Its: _1 st VP___________                 Its: __VP Finance_______
                                         
                                         
ADDRESS FOR NOTICES:                     ADDRESS FOR NOTICES:
                                         
125 South Main Street                    5855 Interface Drive
Ann Arbor, MI 48104                      Ann Arbor, MI 48103
                                         
                                         
Fax/Telex No. 313-995-8000               Fax/Telex No. 313-769-1047____________