File:Ph decree no 1596.png

Summary
The Philippines included most part of Spratly Islands to its sovereignty in 1978, the red lines are based on the Presidential Decree No. 1596 published in 1978:

https://www.officialgazette.gov.ph/1978/06/11/presidential-decree-no-1596-s-1978/

Green lines are are based on Treaty of Paris (1898): "The Treaty of Peace between the United States of America and the Kingdom of Spain", commonly known as the Treaty of Paris of 1898"