Seems to me that "label" is a better term to use than "prefix".

I suppose the fellas who leap in screaming that a thread should be down below the salt might be scared lest someone turn it in a musical direction, and so blur the distinction.

Of course, once it's down there, however musical it turns, it never seems to make the trip upstairs.

The interesting thing is how the divude demonstrates the truth of what has been said by so many people all along - there are, and always have been, far more musical threads than non-musical ones. The more signifucant distinction is surely between the real gems and the dross, and, inevitably, the former are pretty scarce, both upstairs and downstairs..,.