1987 Constitution of the Philippines
Section 4.Any amendment to, or revision of, this Constitution under Section 1 hereof shall be valid when ratified by a majority of the votes cast in a plebiscite which shall be held not earlier than sixty days nor later than ninety days after the approval of such amendment or revision.
Any amendment under Section 2 hereof shall be valid when ratified by a majority of the votes cast in a plebiscite which shall be held not earlier than sixty days nor later than ninety days after the certification by the Commission on Elections of the sufficiency of the petition.