About Datum Curves
With the exception of imported geometry, the foundation of all 3D geometry in Creo starts with a 2D section. Datum curves allow you to create a 2D section that can be used to create many other features such as an extrusion or a revolve. Also datum curves can be used to create a trajectory for swept features.
The Datum Curve tool can be accessed by clicking Model > Datum > Curve.