You can use the Classify Surfaces command to automatically categorize the surfaces of the reference model into core, cavity, and undercut surface regions. The surfaces are classified on the basis of the draft angle in the default pull direction. The classified surfaces are created as parting surfaces. The quilts of the core, cavity, and undercut regions are displayed in unique colors.

Although, the surfaces are automatically classified, you can add or remove surfaces from the surface regions. You can select a different color theme from the Theme list, on the File tab. On the Regions tab, you can shade the Core, Cavity, or Slider region to analyze the surfaces in that region.