> In one of my alternative incarnations, I am a zoological taxonomist.
> One of the big issues for taxonomy right now is whether to accept as
> nomenclaturally valid papers that are published only in electronic
> form, i.e. not printed on paper by a publisher.
> 
> In a discussion of this matter, a colleague has claimed

> 
> > [PDF files will not become unreadable] in the next 30-40 years.
> > Possibly not in the 20 years that will follow. After that, when only
> > 30-year and older documents are in the PDF format, the danger will
> > increase that this information will not be readable any more. It is
> > generally considered as quite unlikely that PDF will be readable in
> > 100 years.

Setting aside the paper/electronic argument, in terms of canonical files for
documents intended for long-term preservation, PDF seems a very weak choice.
Whether or not the actual files will "last" 100 years (I assume that we mean
that they won't degrade to the point of nonreadability), using a proprietary
binary format that doesn't readily convert to other formats seems a poor
choice. 

Why not have the documents be sourced in one of the XML-based formats such
as DocBook or DITA (well-documented, open, text-based, single-source
publication formats)? Then you can have your PDF and preserve it too.
(Donning tinfoil hat) You could even produce a handful of paper-based
documents and hide them in caves around the world. 

Karen G. Schneider