The periods specified by this Act or any order issued under this Act shall be determined as follows:
1. The first day of a period shall not be counted: Provided, That the foregoing shall not apply where a period commences at midnight;
2. If a period is expressed in months or years, it shall be counted according to the calendar;
3. If the start of a period does not coincide with the beginning of a month or year, the period shall expire on the day immediately preceding the date in the last month or year of the period corresponding to the date when the period commenced: Provided, That if a period is counted by months or years but there is no corresponding day in the last month, the period shall expire on the last day of that month;
4. If the last day of a period for performing a patent-related procedure falls on an official holiday (including the Workers' Day designated under the Designation of Workers' Day Act and Saturdays), the period shall expire on the working day following such official holiday.[This Article Wholly Amended on Jun. 11, 2014]