I've read of the S shape but I changed it to § but this one has a circle around a point, your point of interest, the main part of the person.
You want to keep in mind this § shape when you go to take pictures though because it adds and interesting twist. This is hard to accomplish with some people because they are too busy thinking about twisting, stretching, how to place their body and end up looking terrible and not accomplishing any of the modeling techniques.
But this also goes for scenery shots and others whether it's a curving stream, railroad tracks, the sculptured shape of a vase full of flowers, or the subtle curve of a model's body; get the § in the shot.
Yes § but not limited to §, if you pull of a double §§ that's fine as well as long as you're not stretching it too far.
This "S" is created by just having the model position herself in a pose that created the shape for me. Often, this is a very subtle extension of the hips, or the turn of a leg or arm to get the desired "S" in the shot.
Secondly, when doing that, make the picture even more interesting by forcing that "S" to cross the image in the diagonal across your picture - not straight up and down in the center of the frame.
The easiest way to make that even more pronounced is to simply tilt your camera a bit past vertical, forcing the "S" to take a diagonal line. In this example, I've tilted and re-cropped a picture to give you an idea of what I mean.
What this also demonstrates is the fact that even photos that weren't originally shot as they probably should have been, can still be resurrected by creative cropping.