.S01 Files

Files with extensions like: s01, s02, s03, etc. are RAR files. The original RAR-file naming convention used three-digit extensions. So when an archive had over 100 segments, after somefile.r99 would be somefile.s00, and then somefile.s01, etc.

TechSono software uses S** to denote these old RAR files. So, if you see it on SuperNZB’s file-types window for example, that’s what it’s for.