If my understanding is correct, all of the compacts are B (firing pin Block) guns.
Earlier full sized guns would not have this, nor do the late Target(match) models, but this safety measure is incorporated into all others. You will find similar blocker s on other makes as it was some type mandate, even 1911 design autos.
D stands for decocker btw.
I am sure someone will correct me if I am wrong!