Setting the record straight about misinformation about songs can be quite imnportant. Songbook and record slieves do pass on an awful lot of tosh sonetimes. It's really a type of folklore in itself.

I think Joe's haphazard approach is the right way. Costructing some elegant and scholarly framework isn't going to happen, I'd predict, and if it did, it'd turn out to be the wrong framework anyway. Organic beats engineered in these matters, I think.