Over the years various modifications have been proposed to the Constitution of the Philippines, including possible transition to a federal system as part of a shift to a parliamentary system. In 2004, Philippine President Gloria Macapagal Arroyo established the Consultative Commission which suggested such a Charter Change but no action was taken by the Philippine Congress to amend the 1987 Constitution.
What type of modifications been added to the Philippines Constitution? 
possible transition to a federal system as part of a shift to a parliamentary system.