Concentricity Dimension: This tells if a line reducible feature is on the same line as another line reducible feature. This is intended to see if a pin and a hole will mate without interference. If the pin is not concentric to a hole (i.e., the pin is angled too drastically) then the pin will interfere with the edges of the hole. Make sure when measuring a cylinder that you measure 3 points at the top of the cylinder, 3 points at the bottom, and the rest of the points in between the aforementioned points.
For more information on Concentricity, review the download below.
Click here to download: Measure GD&T Functional Explanation