Oolite Bulletins

Worked a treat, thanks for the help.

To have this lovely bit of kit help to locate such things as the Seedy Space Bars and the Hoopy Casinos, we are guided to set the compass to 'b' or 'c'. What does this mean, how do we do it....please help. I cannot find any of these stations having installed them. How do i set the compass to 'b' or ...