Simplify the following text for a Grade 10 native English-speaking person.
Original: On October 28 , 2003 , effected on the Executive Order 246 , Calamba City was designated as the regional center of Region IV-A CALABARZON .
Simplified: Calamba City is also the Regional Center of CALABARZON . Declared by Former President Gloria Macapagal-Arroyo in the Executive Order No. 246 , dated October 28 , 2003 , designated Calamba City as the regional center of CALABARZON .