I have a few beginner questions about tesselation that I really have no clue.

The opengl wiki doesn't seem to talk anything about the details.

What is the relationship between TCS layout out and TES layout in?

How does the tesselator know how control points are organized?

    e.g. If TES input requests triangles, but TCS can output N vertices.

       What happens in this case?
In this article,

http://www.informit.com/articles/article.aspx?p=2120983

the isoline example TCS out=4, but TES in=isoline.
And gl_TessCoord is only a single one.
So which ones are the control points?
How are tesselator building primitives?