9 rules re: formal validity of wills

Here is a summary of rules regarding the formal validity of wills executed by Filipinos or aliens, whether within or outside the Philippines.

[1] If executed by a Filipino in the Philippines, follow Philippine rules.
[2] If executed by a Filipino outside the Philippines, follow Philippine rules.
[3] If executed by a Filipino outside the Philippines, follow rules of the place where the will is executed.
[4] If executed by an alien in the Philippines, follow Philippines rules.
[5] If executed by an alien in the Philippines, follow rules of the country of which he is a citizen or subject. Basically, this means national law.
[6] If executed by an alien outside the Philippines, follow rules of the country where the will is executed.
[7] If executed by an alien outside the Philippines, follow rules of the country of his residence.
[8] If executed by an alien outside the Philippines, follow rules of his country (national law).
[9] If executed by an alien outside the Philippines, follow Philippine rules.

In short, a Filipino or an alien, whether within or without the Philippines, may use Philippine rules of formal validity and, as far as Philippine courts are concerned, the will is formally valid.