.NWF File Extension
What is an NWF file?
CAD project file created by Navisworks, a software package used for engineering design review; saves references to project asset CAD files (such as .DWG files) which make up the file set; used for storing collections of working files together.
An NWF can be published to an .NWD file, which stores all project assets in a standalone document for review. Choose File → Publish from the Navisworks Manage application menu.