Sketcher > Creating Sketcher Geometry > Points, Centerlines, and Coordinate Systems > About Points and Centerlines
  
About Points and Centerlines
You can create construction points, construction centerlines, datum points, and datum centerlines.
Points and centerlines are represented in the graphics window in different default colors and line styles. You can customize these settings in the System Appearance area of the Creo Parametric Options dialog box.
The Difference Between Construction and Datum Entities
Construction points and centerlines are sketching aids and cannot be referenced outside Sketcher. Datum entities convey feature-level information outside of Sketcher. Use datum entities to add information to sketched curve features and sketch-based features in 2D and 3D Sketcher.
To change a construction entity to a datum entity, click the entity and choose Solid on the mini toolbar. To change a datum entity to a construction entity, click the entity then choose Construction on the mini toolbar.
Using Datum Points
You can create datum points and centerline in a sketch and then use it when you create entities in Part or Assembly mode. The following table provides information about the connections between the features and the datum entities.
Feature
Entity Created by a Datum Point
Entity Created by a Datum Centerline
Sketched curve
Datum point
Datum axis
Extrude
Axis through the point and normal to the sketch plane
Sketched pattern
Pattern instance
Revolve feature
Axis of rotation
All other sketch-based features
No geometry is created
No geometry is created
Other features that use Sketcher points or centerlines to convey feature-level geometry
No geometry is created
No geometry is created
Using Datum Entities and Features
Keep in mind the following points when sketching an axis of rotation for a revolve feature or when placing a hole feature:
• When a sketch for a Revolve feature includes several geometry centerlines, the first centerline you create is automatically designated as the axis of revolution.
• To designate a datum or construction centerline as the axthis of revolution or to select a different datum or construction centerline as the axis of rotation, select the centerline and right-click and choose Designate Axis of Revolution on the shortcut menu.