ZIP

ZIP is an archive file format with optional lossless compression. It is used in Source for the pakfile lump in BSP files, as well as for bonus map BMZ files. It is also most likely used to store game data for the Xbox 360 (or other consoles) version of Source games^[1]. The ZIP file format supports several different compression format, although Source only supports uncompressed and, in some engine branches,  LZMA.

Warning:Only certain engine branches and BSP versions support compressed pakfiles; and do, but and do not!

Additionally, the ZIP file format is used for the PK3 and PK4 files used by id Tech 3 and id Tech 4, respectively, which use the standard  Deflate compression instead.

Structs

Todo: See Source 2013 Multiplayer and Source 2013 Singleplayer versions of zip_uncompressed.h, containing the structs used by Source to load ZIP files

Unlike most file formats, a ZIP file's header is near the end of the file, meaning that if, for example, a ZIP file is concatenated to the end of a PAK file, the resulting file will be both a valid PAK file and a valid ZIP file.

See also

• PAK, uncompressed archive format used by id Tech 2 and GoldSrc
• VPK, uncompressed archive format used by Source and Source 2
• GCF, uncompressed archive format formerly used by Steam, prior to the SteamPipe update.
• BZ2, single-file compression format used by FastDL servers (only in )

External links

•  ZIP (file format) on Wikipedia

References

References
1. User:kr0tchet - Currently I only seen that from the Postal III leaked Xbox 360 build (the zip file was named as zip0.360.zip), and can be only opened by using 7-Zip (WinRAR cause an error about unexpected end of archive), not sure if console's The Orange Box also store some it's game files to ZIP aswell.