PDF is also future-proof. At least, it can be. A PDF file is just a collection of pages described in the Postscript language. The page "object" is then compr

PDF is also future-proof. At least, it can be. A PDF file is just a collection of pages described in the Postscript language. The page "object" is then compressed and some metadata is built around it to produce the PDF. There are tools which will extract the pages in their (plain text) Postscript form.