Mysterious, what did you search for? Because "mobi file format" surfaced the LoC page https://www.loc.gov/preservation/digital/formats/fdd/fdd000472.shtml http

Mysterious, what did you search for? Because "mobi file format" surfaced the LoC page https://www.loc.gov/preservation/digital/formats/fdd/fdd000472.shtml https://www.loc.gov/preservation/digital/formats/fdd/fdd0004... which leads one to https://wiki.mobileread.com/wiki/MOBI https://wiki.mobileread.com/wiki/MOBI which seems pretty fleshed out