Interesting. I hadn't heard it described like that before. I really thought it had to do with the placement in terms of the octave. I think I got that from a book called guitar players handbook.
So there's one question for the workshiop next month. I too thought it was relative placement, but this changes my mind. It is the b7 that determines it.
C E G D we call C add 9, but when we add the bB, it suddenly becomes a 9th chord. Mmmmmm....
The second question is do we call C E G bB F a C11 or C7 11th?
And I know it was labeled a 6/7 in my Led Zep song book. But I think this topic we've been on really illustrates how subjective music can be. It really depends on your perspective I think, especially with some of these odd extended jazz style chords. For example 2 chords from Terrapin, as named here on the site:
The first one is named a D#m7-5 and the second is named a C9. if you look closely, they are basically the ninth blues chord w/o the root played on the A string. But since that note isn't played why is the second called a C9 and not an Em7-5? There actually isn't a C played in the second chord at all. And why not vice versa with the other chord? Why isn't it a B9? I think it's your perspective...and context perhaps. The C9 follows and is followed by an Fmaj7, so maybe that has something to do with it. Thoughts?
I honestly have never heard of a 6/7 chord. It doesn't mean they don't exist. So there's another question.
I think you nailed it in one. It is context. One thing to remember is that the transcriber is also listening to the bass player. So if the bass plays D# then C that will help place the chords in context. I many times play chords missing the root, because the bass player and rhythm guitar are filling in that information, so I can add color.
The opening chord of Stormy Monday as done by the Allmans is:
There is no G yet the book labels it a G9. Taking it out of context, I would call it an E (or B, A or D) diminished. But once I heard the bass player hit that G, we'd know where he was.
I just thought of an example of an interesting new naming convention, and a resaon why you might be right about the extended tone being in another register.
In Bojangles, in C we walk down the C to Am sequence. That second form, with the B in the bass, is termed C/B. But it could be seen as a Cmaj7. It could also be seen as C add 2.
BTW, a dash(-)indicates diminished, not minor I believe. Anyway, peace.
It means to flat the following note. That will make it either minor or diminished, depending on context. (There's that word again).
As always I might be wrong but I'm certain.