Question: What is an .nwf (review) file?
Answer:
Review files are useful when using the native CAD files appended into Autodesk Navisworks. They store the location of the appended files, along with any design reviews made in Autodesk Navisworks, such as comments, redlines, viewpoints, animations and so on.
If a group of files is appended into an Autodesk Navisworks scene, and saved as an NWF file, then on re-opening this NWF file later, once the original CAD files have been changed, the updated CAD files will be loaded into the scene for review.