Sketcher > Creating Sketcher Geometry > Points, Centerlines, and Coordinate Systems > Datum Points, Centerlines, and Coordinate Systems > To Create a Datum Centerline
  
To Create a Datum Centerline
1. In the Datum group, click Centerline.
2. Select a point for the first point. A centerline that rubberbands to the pointer is created.
3. Select another point on the centerline. The datum centerline is placed.