If there are curves in the IGES file or if there are different levels (or layers) in the IGES file, the IGES-In Surfaces, Curves, and Levels dialog box appears. Levels are sometimes used by other systems to separate assembly components or to separate IGES entity types.
To select the desired entities and levels:
Select Include surfaces to import any surfaces in the file, if applicable.
Select Include curves to import any curves in the file, if applicable.
Select the levels to include:
Include all levels. All levels are imported to level zero.
Include levels. Only the specified levels are imported to level zero.
Click OK to exit the IGES-In Surfaces, Curves, and Levels dialog box or click Cancel to abort the import process.