Interface > Working with Imported Geometry > Working with Imported Faceted Geometry > About Using Imported Faceted Geometry for Datum Creation
  
About Using Imported Faceted Geometry for Datum Creation
You can reference faces, edges, and vertices of the faceted data for the creation of datum features such as planes and axis. You can use facet geometry or a combination of facet and exact geometry as reference for the creation of datum features.
Create datum features referencing facet geometry as follows:
Datum plane—Facet vertices, facet edges, and facet faces
Standard datum point—Only facet vertices
Field datum point—Only facet faces
Datum axis—Facet faces, facet edges, and vertices
You can use normal, parallel, through, offset, and angular constraints for faceted references. If angle or offset constraints are used, you can only set the initial offset value or specify the initial angle. You cannot modify or change the angle or the offset value after the datum feature is created because the reference data is internally frozen at the initial creation location and the angle or offset parameters are not actually created.
There is no association between the faceted data and the datum features created by referencing the faceted data. The datum features are independent of the faceted geometric references and do not fail even if you delete the faceted data from the part, suppress, or redefine it.
References to faceted geometry are not stored or maintained in the feature. Any reference made to the faceted geometry creates an internally frozen reference that does not change. You can redefine, but not reroute, faceted references. During redefinition, all faceted references appear as frozen references that can be removed and replaced as required. For a combination of exact and faceted geometric references, you can edit the exact-geometry references and not the facet-geometry references. You can delete facet references and select new facet references when editing the definition of datum features.