Post WWII perfin

I tried to write on my facebook but the result isn't as good as here, so I'm coming back.

Acquired these two a few months ago among a small lot, thought it was interesting. Perfin after WWII for security purposes wasn't as common as pre-war. The other one I had on a 1950s Sarawak stamp was sold for a few bucks a couple of years ago. I'm hoping to gain some knowledge on post-WWII perfin in Asia, so I'll keep these two for a while for reference. I am no expert in this field, so I'll be grateful if someone can comment on this or refer me to some reading or information.

My next posting will be a KALAKA, SARAWAK postmark, and I hope g-matang will get ready to comment on it :)