FOS file format

The Fallout 3 Savegame format (*.fos), shows some similarities with the Oblivion format. Discoveries about the FO3 format will be posted on this page. In addition, the Xbox 360 file format for the Fallout 3 Savegame format (*.fxs) closely resembles the PC format from offset 0000D000 on, however currently the two are not interchangeable like it was for Oblivion. Most of the information found here is derived/abstracted from this page.

General Information
If there's a Byte Offset value in the table, it means it's fixed (i.e. for every save file).

Each row in the table represents a Byte-Block, generally separated by a 7C byte (ASCII: "|").

Example: Offset     0  1  2  3  4  5  6  7   8  9  A  B  C  D  E  F

00000000  46 4F 33 53 41 56 45 47  41 4D 45 56 00 00 00 30   FO3SAVEGAMEV...0 00000010  00 00 00 7C 00 02 00 00  7C 40 01 00 00 7C 05 00   ...|....|@...|.. 00000020  00 00 7C 07 00 7C 41 68  6C 65 65 6E 61 7C 0C 00   ..|..|Ahleena|.. 00000030  7C 56 61 75 6C 74 20 4D  61 72 74 79 72 7C 02 00   |Vault Martyr|.. 00000040  00 00 7C 11 00 7C 4D 6F  72 69 61 72 74 79 27 73   ..|..|Moriarty's 00000050   20 53 61 6C 6F 6F 6E 7C  09 00 7C 30 30 31 2E 34    Saloon|..|001.4 00000060  35 2E 32 38 7C                                     5.28|

Plugins
The following is repeated for each active plugin (see pluginCount, above):