The reference point I noted above was my attempt to show where the profile was being located relative to the axis of rotation and the origin. It's being used as the anchor point for the profile. If you think of that profile it's like a sub-sketch and it is fully defined within itself. The only thing it needs is an X-Y location to lock it into place. If it was not constrained horizontal to the origin and that 4" dimension wasn't there all the entities in the profile part of the sketch would be blue and you could drag the profile around the sketch (it would retain it's shape and size). Adding the 4" dimension only would result in being able to drag the profile up and down but not left and right. Once you have defined an X-Y location for any point in the profile all the entities will turn black and you would not be able to move the profile in any direction by dragging.