ESP/ESM format description or library to edit?

[ezze]

As the subject line suggest, is there an accurate description of the ESM/ESP file format for Oblivion?
Otherwise, even better is there any usable lib to easily parse and modify those files programmatically? I have a little idea I would like to implement.

I am aware that this project is directed at TES3, but perhaps anyone can help.

[Capostrophic]

xEdit record definitions are probably the most accurate. You could also check cc9cii's raw, limited TES4/TES5 ESM reader implementation.

[silentthief]

I'm not familiar with the file format myself, but the wiki that I link here:

https://en.uesp.net/wiki/Tes4Mod:Mod_File_Format

discusses the file format. There are discussions there for MW, OB and Skyrim as well
(https://en.uesp.net/w/index.php?title=S ... at&button=)

ST

[cc9cii]

My implementation is based on the UESP wiki. There are some differences but not much.