https://github.com/WrinklyNinja/fopdoc
FallOut (3 & New Vegas) Plugin (File Format) Doc(umentation)
I've recently finished the bulk of my work in documenting the Fallout 3 plugin file format using the information contained in the TES5Edit source code, so I thought I'd create a thread to help "spread the word". AFAIK, it's the only documentation available.
I plan on also documenting the Fallout: New Vegas plugin file format.