What is it?
DWF Vista Shell Integrations for Autodesk DWF Viewer allows you to view and print 2D and 3D drawings, maps, and models created in the DWF format. Design Web Format (DWF) is a secure file format developed by Autodesk for the efficient distribution and communication of rich design data to anyone who needs to view, review, or print design files.
Description of dwf_vshell.dll from Autodesk
“Accelerate your design reviews on your desktop with Autodesk® Design Review software. It’s the free, all-digital way to view, mark up, print, and track changes to Autodesk 2D and 3D files—without the original design software. Work with a wide variety of file formats, including DWF and DWFx, DWG and DXF (requires installation of free DWG TrueView software) and Adobe PDF, as well as several image file types including .bmp, .jpg, .gif, .pcx, .pct, .png, .rlc, .tga, .tif, .mil, .cal, and more.”