Why is there a B key included with the space bar set? This is obviously for some exotic layout but I'm curious which one(s)

Over the years of collecting mechanical keyboard switches, I’ve been lucky enough to have encountered dozens upon dozens of rare and unique ones that have stuck in my mind to this day. Prototypes, factory errors, and even a few switches so rare that there is literally zero documentation about them anywhere in the world all fill that personal list from top to bottom. However, I realize that talking about switches so far outside of most people’s reaches, and even sometimes my own grasp, doesn’t make for the most exciting of articles about switches. To this newest generation of keyboard enthusiasts, though, there is one pretty rare MX-style switch which has made its way to the top of everyone’s “must try” lists – Cherry MX Locks. These often undiscussed and even more rarely seen switches are something that few people have seen and even fewer have had the chance to try at a meetup before. However, the list of people who really know how these unique Cherry switches work is even shorter...