Chapter 5 Legal Weights Measures and Period SEC. 16. Official Use of Metric System. - The metric system of weights and measures shall be used in the Autonomous Region for all products, articles, goods, commodities, materials, merchandise, utilities, services, as well as for commercial transactions like contracts, agreements, deeds and other legal instruments publicly and officially attested, and for all official documents. Only weights and measures of the metric system shall be officially sealed and licensed. SEC. 17. Legal Periods. - "Year" shall be understood to be twelve calendar months; "month" of thirty days, unless it refers to a specific Gregorian calendar month in which case it shall be computed according to the number of days the specific month contains; "day," to a day of twenty-four hours; and "night," from sunset to sunrise. Chapter 6 General Principles Governing Public Officers SEC. 18. Nature of Public Office. - Public office is a sacred public trust. Public officers and employees must at all times be accountable to God and to the people, serve as ”khalifa”, with the utmost responsibility, integrity, loyalty and efficiency, act with patriotism and justice, and lead modest lives. SEC. 19. Declaration of Assets, Liabilities and Networth. - A Public officer or employee shall upon assumption to office and as often thereafter as maybe required by law, submits a declaration under oath of his/her assets, liabilities and networth. SEC. 20. Ethics in Government. - All public officers and employees shall be guided by the core values of Islamic development such as: predictability, stewardship, transparency, honesty, integrity, and consensus-building in the performance of their duties and functions. SEC. 21. Dress Code. – The dress code for all Muslim officials and employees shall, as much as possible, conform to Islamic standards and traditions, and those for non-Muslims shall conform to existing Civil Service dress code. SEC. 22. Inhibition Against Purchase of Property on Tax Sale. - No officer or employee of the government shall purchase directly or indirectly any property sold by the government for the non-payment of any tax, fee or other public charge. Any such purchase by an officer or employee shall be void. SEC. 23. Powers Incidental to Taking of Testimony. - When authority to take testimony or receive evidence is conferred upon any administrative officer or any non-judicial person, committee, or other body, such authority shall include the power to administer oaths, summon witnesses, and require the production of documents by a subpoena duces tecum. SEC. 24. Liability of Superior Officers. - (1) A public officer shall not be civilly liable for acts done in the performance of his/her official duties, unless there is a clear showing of bad faith, malice or gross negligence. 7