A DWFx (Design Web Format XPS) is a a formatted representation of 2D/3D drawing as XPS document. It contains graphics and text as part of design data. It is the newest version of DWF file format and can be viewed and printed with the Microsoft XPS Viewer. The XPS nature of these files lets you share the design data with reviewers without requiring them to install Autodesk Design Review.
Similar to DWF, DWFx is developed by Autodesk in compressed format to make transmission over the internet suitable. A single DWFx file can contain one or multiple drawings and sheet sets.