TDE documentation

Hi, I am wondering if there are any design documents for KDE3/TDE. I have seen here and there in the code some explanations or README files with design drafts. I doubt there are such documents, but still asking for confirmation. It is hard to always draw a design from the code. When it comes to testing or changes use cases are very useful, so I am wondering if there are such documents somewhere. Or how do you usually work with the code? regards