- because there is still no a "fixed" configuration options format,
- we are trying to find a better ways to define some options related to devices type, power etc.
- when you use the configurator you don't need to bother about this.
- for now there is no "B=" and "b=" options in the configurator, wait for next updates.
(how have you got this configuration?)
In short - it is the electric bus number (1-6) and brightness channel number (use in your virtual plane panel) https://simvim.com/simcom/index.php/1954/7-segments-brightness