SWG (SWAG packet) is a specialized archive format associated with the SourceWare Archival Group (SWAG). SWAG is a historical collection of Pascal source code.
There are at least two different SWG formats, which we'll call "old" and "new".
New SWG format is a derivative of LHA format, apparently based on LHA header level 0, with an extra 165 bytes worth of headers preceding the filename field. It has a custom "
-sw1-" compression method, the details of which are apparently undocumented.
New format: At offset 2 is ASCII "
-sw1-" (if the first member file was compressible), or "
-sw0-" (if not).
At least some old format files start with "
- SWAG.ZIP → SWAGADD.DOC - Has partial documentation of new format.
- swg.txt - Excerpt from SWAGADD.DOC
-  → SWAG.ZIP - GDSOFT SWAG Packet Reader v3.13 (DOS software)
- Note that the Reader is also included in the ALLSWAGS.ZIP file.
-  → SWAGWIN.ZIP - SWAG for WINDOWS, v1.04
- SWAG.ZIP - Maybe the first version (DOS software)
- GARBO Shareware Archive → allswags.zip
-  → ALLSWAGS.ZIP
- SWAGABC.ZIP - Old format
- The HTML SWAG Home Page - The contents of SWAG are available here, but maybe not in SWG format.