FiltReg
Note
Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.
The FiltReg.exe program inspects filter installation information in the registry. You invoke the filtreg.exe program from the command line simply by typing its name:
filtreg
Filtreg.exe enumerates all file name extensions that have filters associated with them by printing the file name extension and the name of the filter DLL for the extension. This is a simple way to verify the correct installation of a filter.