You say, "Amy, Amy,... Let's be level headed about this. Why would they want to do that?"
I don't know. I couldn't say. All I know is, all of a sudden THIS
Showed up in the piece I was studying in the book, Jazz Composition and Arranging In the Digital Age.
The first time I was thrown a curve ball, I thought, "Oh, I must have forgotten when they talked about that." The next time, "Gee, this is weird. When did they talk about this?"
BUT NOT THIS TIME!!! They didn't cover what this chord symbol means. Not once did they mention it before. I caught them red-handed trying to mess me up!
However, you will be happy to know that I have figured it out again. And thank goodness, because there's not a lot out there on this topic either.
This is not a Cm9 chord trying to be cagey with roman numerals. Oh no, actually, this is a C chord where the player needs to switch his thinking to the Mixolydian Mode.
Remember this?
So, here's how this works. Here you see the Mixolydian Mode in G, because if you play only the white keys in the G scale, you will play the mixolydian mode. But of course, you will need to adjust for any other scale you play, i.e. C or A or whichever other scale. For more on modes click here.
The reason they use this is to allow for soloists to know where they can go within the key. Trust me, if you're in the midst of a solo, you want to know everything you can before going into it - lest you look very, very foolish.
So, brush up on your modes! I know I'm trying to.
In the future if you see "Cmix" or "Gdor", which are usually typed as "C Mix" or "G Dor"(G in Dorian Mode) or any other mix of Chord and Mode, remember this blog or get the book: The Structure & Analysis of the Modern Improvised Line