SQX

SQX is an open-source archive format developed by Sven Ritter, Rainer Nausedat, and SpeedProject. It seems to have been created as part of the development of its primary implementation, a program called "Squeez", which originated in 1993 as a utility for manipulating common archive formats, with no format of its own. (See Squeeze for a list of formats with similar names.)

The source code download includes a text file giving file format details. The source code is archived as a .sqx file itself, but fortunately an SQX extractor is also included as a standalone Windows .exe. (Bad luck for users of any non-Windows platform, though.)

Identification
ASCII "" appears at offset 7. Though this is reminiscent of LHA compression identifiers, SQX is not closely related to LHA.

Links

 * Wikipedia article
 * Official site (from archive.org)
 * Total SQX plugin for Total Commander file manager
 * Some discussion of SQX

Software

 * Squeez 5

Sample files

 * https://telparia.com/fileFormatSamples/archive/sqx/