[gioele]

> PDF is probably the best choice for preserving “design”, but I wouldn’t trust it for preserving content any more than any other format. Always keep a plain text copy.

I agree, but have a look at PDF/A (A is for Archiv{e|al}): http://en.wikipedia.org/wiki/PDF/A

> PDF/A is an ISO-standardized version of the Portable Document Format (PDF) specialized for the digital preservation of electronic documents.

> PDF/A differs from PDF by omitting features ill-suited to long-term archiving, such as font linking (as opposed to font embedding).