Holy rapid responses. Thanks.

Bud, what's a prime? Is that the same as a tonic? I've seen the one-circle/two-lines symbol that you mention - I always thought that meant that the sopranos and altos were singing the same note temporarily.

Sorcha, or anyone, I thought when you play a fingered 4th with the matching open string that was called a unison, and playing two fretted notes simultaneously was a double stop, and playing a fretted note with a non-matching open string was a drone. Is this more or less right?

Thanks, Marion