Beretta trigger guard markings?

[Eddie1965]

I have an Italian made 92fs inox and it has 3 markings on the trigger guard. I know that the 2 letter markings are the year it was made, 1990 in my case, the other 2 are a small shield which is on the barrel as well and the other one is PSF with a star over the letters.

I tried taking pictures but my camera can focus on those small markings.

[Mickey D]

Proof markings