The breadth of the IGES specification makes it impractical for any receiving application to correctly interpret every IGES entity. Usually, you should exclude an entity that is not supported by the receiving application.

If you exclude an IGES entity listed in the section Alternate entities to use when exporting excluded IGES entities, the geometry that it represents is approximated with the corresponding alternate entity type. In most cases, the approximation is less compact and "intelligent" than the entity it replaces.

The Exclude IGES Entities dialog lets you exclude IGES entities. You can open the Exclude IGES Entities dialog by choosing Settings > Exclude IGES Entities from the Export IGES File dialog.

Examples include the following:

• If the general note IGES entity (type 212) is excluded, text elements are replaced with their stroked representation as copious data entities (type 106). Although the text appears correctly in the IGES file, it requires much more file space and is interpreted as a series of vectors instead of as text.
• If the receiving application does not support NURBS, they should be excluded.