Use the Center Line Marker tool to indicate the center line on a drawing.
To create a center line marker:
Click the Center Line Marker tool from the Dims/Notes tool set.
Click to place the object in the drawing, and click again to set the rotation.
The first time you use the tool in a file, a properties dialog box opens. Set the default properties, and click OK. The properties can be edited from the Object Info palette.
Click to show/hide the parameters.