SZS (File Extension)
SZS is a file extension used by Nintendo in many of their games when referring to files compressed using the Yaz0 encoding. The extension can be misleading, though, as several different file formats use this extension when compressed. Such formats include U8 (an archive format used in Mario Kart Wii), SARC (an archive format used on the 3DS and Wii U), and BFRES (an update of the BRRES format for the Wii U). Thus, an
.SZS extension does not necessarily indicate which format a given SZS file originated from.
Mario Kart Wii
In Mario Kart Wii, SZS is most commonly associated with the U8 file format, an archive format used for all of the race and battle courses. However, as noted above, other file formats may also use the
.SZS extension; for example, the game's language files, which use SZS, are actually Yaz0-compressed BRRES files.
Mario Kart 8
In Mario Kart 8, there are two different Yaz0-compressed file formats that use the
.SZS extension: SARC, an archive format like U8, and BFRES, a model resource format. Again, this reinforces the fact that SZS files may come from a variety of different file formats.
SZS is only a file extension, not a file format. It is short for Seven Zip Stream (or something similar) and indicates that a file is compressed using Yaz0, Nintendo's favorite compression that has been used since the Nintendo 64. No files should be known as SZS files. They should be known as the file content's file format. SZS files should be decompressed and then analyzed for better knowledge of the actual file format.
The following tools can be used to expand and edit SZS files: