Another quick question—what is the URL for the Belgium Proof marks?

In this regards, I have a Belgium (post 1950’s) 12ga with a German (replacement barrels and forearm) and Belgium history. The are Belgium (View and Nitro) and German (Nitro and Ulm) marks. There are two marks on the water table that I have not traced but must be very well known: a “B” with a “star” (I think?) over the B—the same with a “P”.

Thanks—

Berrien