An .SFV file is a file generated by a program such as WinSFV or QuickSFV. It is used to check a group of downloaded files for errors using a checksum. Whoever posted the files that you downloaded would normally generate the .SFV file and post it. After you downloaded these files, you would run a check to make sure there were no errors when you received them.

To use .SFV files, you need find a copy of WinSFV or QuickSFV. After installing the program, it associates the .SFV extension with QuickSFV or WinSFV.

After you download a large set of files, such as an episode of Doctor Who called The Power of Kroll, you can check the files to verify that there were no errors when you downloaded the files.

An example of what is in an .SFV file:

; Generated by WIN-SFV32 v1.01a on 2000-10-09 at 02:03.28
;     10000000  01:46.24 2000-10-09 Kroll_DiVX_1of4.r00
;     10000000  01:46.26 2000-10-09 Kroll_DiVX_1of4.r01
;     10000000  01:46.28 2000-10-09 Kroll_DiVX_1of4.r02
;     10000000  01:46.30 2000-10-09 Kroll_DiVX_1of4.r03
;     10000000  01:46.32 2000-10-09 Kroll_DiVX_1of4.r04
;     10000000  01:46.34 2000-10-09 Kroll_DiVX_1of4.r05
;     10000000  01:46.36 2000-10-09 Kroll_DiVX_1of4.r06
;     10000000  01:46.40 2000-10-09 Kroll_DiVX_1of4.r07
;     10000000  01:46.42 2000-10-09 Kroll_DiVX_1of4.r08
;      8917545  01:46.44 2000-10-09 Kroll_DiVX_1of4.r09
;     10000000  01:46.22 2000-10-09 Kroll_DiVX_1of4.rar
Kroll_DiVX_1of4.r00 CC70127C
Kroll_DiVX_1of4.r01 82A866AC
Kroll_DiVX_1of4.r02 3ACB391B
Kroll_DiVX_1of4.r03 EB7A42DE
Kroll_DiVX_1of4.r04 49D9DFD0
Kroll_DiVX_1of4.r05 6ACCD727
Kroll_DiVX_1of4.r06 9502EBB4
Kroll_DiVX_1of4.r07 F4485E7B
Kroll_DiVX_1of4.r08 107E8E54
Kroll_DiVX_1of4.r09 DBE77D6D
Kroll_DiVX_1of4.rar D0916789

The first part of the program lists the files to be checked, and their file sizes. Note that each part is about 10 megs in size. The second part of the .SFV file has the names of each file and the CRC checksum for each part. When you run the .SFV program, it generates a CRC checksum and compares it to the checksum in the file. If they don't match, the program will tell you. You may need to re-download the bad part to get a complete episode of Doctor Who.

If you are unfamiliar with the extension .RAR and .R00, .R01 etc., it is a file archiver program similar to WinZip. It uses the RAR compression technique, and if preferred on Usenet because you can set individual part sizes. If I unarchived the file Kroll_DiVX_1of4.rar, it would be a file that was about 108 megs in size.