The bet is that PDFs are so popular that _someone_ (the archival 
community if no-one else, but probably someone else) will ensure that 
they continue to be readable somehow.

These are real non-trivial issues in electronic archiving though, issues 
that the archival community.  It is generally a safe assumption that 
good electronic archiving over the decades-and-more term requires some 
regular attention by an electronic archivist to make sure that files 
remain readable, and are converted to new formats when necessary. As 
well as attention to avoiding actual bit-level corruption of files. You 
can't neccesarily just dump files on a HD and ignore them and expect 
they'll be readable in 100 years, that much is true -- and true pretty 
much regardless of particular electronic format you choose.

As far as electronic formats go, I think PDF is as good as anything -- 
except maybe plain ASCII text, which is not nearly as useable (and 
doesn't allow diagrams, mathematical equations, non-English letters, 
etc). I don't know why you're colleague has decided that "30-40 years" 
is the horizon after which PDF specifically will become "unreadable", 
this seems like just a wild guess to me, but it would be interesting to 
see if he has any particular evidence to back up this claim. 

So there are real issues with electronic archiving, but unless they lead 
you to refuse to accept electronic submissions at all, you're just going 
to have to deal with them, it's not really an issue of PDF specifically, 
but it is true that "just dump files on a HD and forget about them and 
assume they'll be readable in 100 years" is not a particularly safe 
electronic archiving strategy.

Jonathan

Mike Taylor wrote:
> Dear CODE4LIB colleagues,
>
> 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.
>>     
>
> I would appreciate any comments that anyone on this list has on the
> likelihood that PDF will be unreadable in 100 years.
>
> Many thanks,
>
>  _/|_	 ___________________________________________________________________
> /o ) \/  Mike Taylor    <[log in to unmask]>    http://www.miketaylor.org.uk
> )_v__/\  "Can't someone act COMPLETELY OUT OF CHARACTER without arousing
> 	 suspicion?" -- Bob the Angry Flower, www.angryflower.com
>
>