The mysteries of to do lists

I wrote myself a to do list yesterday. Got most of what I wanted to do done. However, there is a slight mystery involved. It says I need to do B.S.C. I have absolutely no idea what that stands for. Hmm... Never mind. I did some revision, some reading, went to book club, tidied various things, but I don't know what this B.S.C. thing is supposed to be. Oh well. If anyone has any ideas...?