K.G. Schneider writes:
 > > > [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.

Just as a point of information, PDF is not proprietary: as of July
2008, it is an ISO standard.

 > 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.

The problem is how we get there from here.  Right now, the world is
full of journals that routinely make available PDFs of the articles
published in them.  Far, far fewer make available any XML-based format
-- in fact, I would imagine that only a tiny minority ever have the
documents in an XML-based format: most will go from MS-Word
submissions to PDF publications.

So the question becomes: if we want to rely on digital preservations
so that we don't need to print, do we first need to persuade the
world's journals to change their publishing practices?  If so, that
doesn't seem like a very realistic goal.

 _/|_	 ___________________________________________________________________
/o ) \/  Mike Taylor    <[log in to unmask]>
)_v__/\  "When I can't fondle the hand I'm fond of, I fondle the hand at
	 hand" -- E. Y. Harburg, "Finian's Rainbow"