[maxxxxx]

PDF has no paragraphs, often not even words. No concept of font notes. It doesn't flow well with different screen sizes.

If you designed a real bad format on purpose, it would be hard to top PDF. Maybe Photoshop files are worse.

[brianwawok]

Have you seen the spec for .doc and .xls ?

[maxxxxx]

I don't even want to know :)

[grkvlt]

Oh, you really do! The format for COM object based documents like XLS and DOC is actually a FAT filesystem: https://en.wikipedia.org/wiki/Compound_File_Binary_Format