<PAGE>
                                                                    EXHIBIT 99.4


  AMERICAN                   CODE OF BUSINESS CONDUCT              CORPORATE
  BUILDING                                                           POLICY
 CONTROL, INC.                   CODE OF ETHICS                        N-2

                                 March 31, 2003                  March 31, 2003

INTRODUCTION:

This Code of Ethics is a part of the Company's Code of Conduct. This Code of
Ethics is established pursuant to Section 406 of the Sarbanes-Oxley Act of 2002,
which requires that the Company establish a code of ethics to apply to the
Company's principal executive officer and certain of the Company's senior
financial officers, including but not limited to, the Company's principal
financial officer, controller, principal accounting officer, or persons
performing similar functions (the "Executive Officers").

The Executive Officers should note that simply complying with Laws or following
widespread business practices may not be enough to comply with this Code of
Ethics. It is therefore very important that the Executive Officers read and
understand this Code of Ethics.

If any Executive Officer has a question regarding this Code of Ethics, then such
Executive Officer should contact the General Counsel. If any Executive Officer
has information, concerns, or suspicions regarding any illegal or unethical
conduct, then such Executive Officer should immediately contact the General
Counsel.

PURPOSE:

The purpose of this Code of Ethics is to deter wrongdoing and to promote:

         (1)      Honest and ethical conduct, including the ethical handling of
                  actual or apparent conflicts of interest between personal and
                  professional relationships;

         (2)      Full, fair, accurate, timely, and understandable disclosure in
                  the periodic reports required to be filed by the Company with
                  the SEC and in the Company's public communications;

         (3)      Compliance with applicable Laws;

         (4)      The prompt internal reporting of violations of this Code of
                  Ethics to an appropriate person or persons identified in this
                  Code of Ethics; and

         (5)      Accountability for adherence to this Code of Ethics.

This Code of Ethics must be applied by the Executive Officers in good faith and
with reasonable business judgment to enable the Company to achieve its operating
and financial goals within the framework of the Law.



<PAGE>


POLICY:

A.       ETHICAL STANDARDS OF CONDUCT

         The Executive Officers must follow the accounting rules and controls
         set forth by the SEC and the Financial Accounting Standards Board.

         The Executive Officers must also comply with the obligations set out in
         the Sarbanes-Oxley Act of 2002.

         Each Executive Officer shall, when required, provide full, fair,
         accurate, timely, and understandable disclosure in the periodic reports
         that the Company is required to file. Accordingly, all account books,
         budgets, project evaluations, expense accounts and other papers
         utilized in maintaining business records must accurately report the
         matters to which they relate.

         All assets and liabilities of the Company must be carefully and
         properly set forth in the Company's financial records. The Company's
         outside accountants must be given full access to all information of the
         Company necessary for them to properly conduct any audit of the Company
         or of any subsidiary or division of the Company.

         No Executive Officer shall conceal a mistake in the Company's financial
         reporting. All such mistakes must be fully disclosed and corrected as
         promptly as possible. Falsification of any Company record is strictly
         prohibited and will result in instant dismissal and possibly criminal
         charges being filed.

         No Executive Officer may request or be granted a loan or payroll
         advance from the Company.

         All Executive Officers must comply with all applicable securities Laws
         and the Company's Insider Trading Policy. See Policy N-6 of the Code of
         Conduct for the Company's Insider Trading Policy.

         The Executive Officers must strive to apply high ethical, moral and
         legal principles in every aspect of their business dealings with other
         Employees, the public, the business community, stockholders, customers,
         suppliers and governmental and regulatory authorities.

         All Executive Officers must avoid any activities that would involve the
         Company in any practice that is not in compliance with this Code of
         Ethics. Any Executive Officer who does not adhere to such standards and
         restrictions is acting outside the scope of his or her employment.

         The Company will not excuse any violation of this Code of Ethics by an
         Executive Officer even if the violation was specifically requested or
         directed by another Executive Officer. Only the Board or the Audit
         Committee can authorize a waiver of this Code of Ethics. See Section 2
         of Part B of this Code of Ethics.

<PAGE>


         Each Executive Officer must alert the Board or the Audit Committee
         whenever an illegal, dishonest, or unethical act is discovered or
         suspected by such Executive Officer. No Executive Officer will be
         penalized by the Company for reporting his or her discovery of such
         acts or for reporting suspicions of such acts provided that such
         Executive Officer is not a party to or responsible (alone or with
         others) for such acts.

         Conflicts of interests are to be avoided by the Executive Officers. A
         conflict of interest exists if an Executive Officer's actions are, or
         could reasonably appear to be, influenced, directly or indirectly, by
         personal considerations or by actual or potential personal benefit or
         gain. See Policy N-4 of the Code of Conduct for the Company's Conflict
         of Interest policy. If a conflict of interest is unavoidable it must be
         disclosed at the earliest opportunity. Conflicts of interests can arise
         with respect to financial and business interests, investments,
         relationships with suppliers, and the offering of prizes, samples,
         gifts, gratuities or incentives.

         The Audit Committee has separately established procedures for the
         receipt of confidential, anonymous submissions by the Company's
         employees of concerns regarding questionable accounting or auditing
         matters.

B.       ADMINISTRATION OF THIS CODE OF ETHICS

         This Code of Ethics shall be administered as follows:

         1.       RESPONSIBILITY FOR ADMINISTRATION

                  The Board or the Audit Committee (the "Ethics Administrator")
                  shall be responsible for interpreting and administering this
                  Code of Ethics. In discharging its responsibilities, the
                  Ethics Administrator may engage such agents and advisors as it
                  shall deem necessary or desirable, including but not limited
                  to attorneys and accountants.

         2.       SCOPE OF THIS CODE OF ETHICS

                  The Ethics Administrator shall periodically, in light of the
                  experience of the Company, review this Code of Ethics. As it
                  deems necessary, the Audit Committee shall make
                  recommendations to the Board to ensure that (i) this Code of
                  Ethics conforms to applicable Law, (ii) this Code of Ethics
                  meets or exceeds industry standards, and (iii) any weaknesses
                  in this Code of Ethics or any other Policy of the Company are
                  revealed through monitoring, auditing, and reporting systems
                  are eliminated or corrected.

         3.       WAIVER OR AMENDMENT OF THIS CODE OF ETHICS

                  The Ethics Administrator may grant a specific, limited waiver
                  of any provision of this Code of Ethics if the Ethics
                  Administrator determines, based on information that the Ethics
                  Administrator deems credible and persuasive, that such a
                  limited waiver is appropriate under the specific circumstances
                  (and each fact situation will be a separate case). If the
                  Ethics Administrator waives any provision of this Code of
                  Ethics, then the Company shall make an immediate disclosure of
                  such waiver in a


<PAGE>

                  manner permitted by applicable Law. This Code of Ethics may be
                  amended only by the Board.

         4.       MONITORING AND AUDITING

                  The information developed by the Company's independent
                  accountants in performing their audit engagement on behalf of
                  the Company by the Company's internal auditors in the
                  performance of their assigned responsibilities shall be made
                  available to the Ethics Administrator as a means of monitoring
                  compliance with this Code of Ethics.

         5.       REPORTING SYSTEM

                  Any suspected violation of this Code of Ethics shall be
                  promptly reported to the Ethics Administrator.

         6.       INVESTIGATION OF VIOLATIONS

                  If the Company receives information regarding an alleged
                  violation of this Code of Ethics, then the Ethics
                  Administrator shall:

                  (1)      evaluate such information as to gravity and
                           credibility;

                  (2)      if necessary, initiate an informal inquiry or a
                           formal investigation with respect thereto:

                  (3)      if appropriate, prepare a written report of the
                           results of such inquiry or investigation, including
                           recommendations as to the disposition of such matter;

                  (4)      if appropriate, make the results of such inquiry or
                           investigation available to the public (including
                           disciplinary action); and

                  (5)      if appropriate, recommend changes to this Code of
                           Ethics that the Ethics Administrator deems necessary
                           or desirable to prevent similar violations of this
                           Code of Ethics.

         7.       DISCIPLINARY MEASURES

                  The Ethics Administrator shall enforce this Code of Ethics
                  through appropriate disciplinary actions. The Ethics
                  Administrator shall determine whether violations of this Code
                  of Ethics have occurred and, if so, shall determine the
                  disciplinary actions to be taken against any Executive Officer
                  who has violated this Code of Ethics.

                  The disciplinary actions available to the Ethics Administrator
                  include counseling, oral or written reprimands, warnings,
                  probations or suspensions (with or without pay), demotions,
                  reductions in salary, terminations of employment, and
                  restitution.


<PAGE>

                  The jurisdiction of the Ethics Administrator shall include, in
                  addition to the Executive Officer that violated this Code of
                  Ethics, any other Employee involved in the wrongdoing such as
                  (i) persons who fail to use reasonable care to detect a
                  violation and (ii) persons who withhold material information
                  about a suspected violation of this Code of Ethics when
                  requested to divulge such information.


                           APPROVED:                     Board of Directors
                                                         March 31, 2003