Repair Document

Documents can occasionally contain damaged or invalid objects when they are imported from other formats, or when crashes or power failures occur while saving a project. 

This command checks the document for damaged items, such as unreferenced hatches, incomplete vertices or zero-length segments, and deletes them. It also rebuilds the internal identification handles of each object and checks the bounds of the windows. 

To repair the document, choose Help ▸ Repair Document. This command cannot be undone.