Bert, I am not convinced that you should have to make it known that you don't want accompaniment. In our mainly instrumental sessions there is an unwritten rule that nobody accompanies a singer unless it is known that they want it and, personaly, I believe it should be that way round. In many cases, with the regulars, you know which songs they want to be accompanied on (and in some case which player(s) they want) but other than that, I would suggest don't join in unless specificaly asked to do so is the polite way.Jon