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Re: .PDF



This message is in response to several of those recently posted, so I
won't quote them all.

* PDF Searchability

It's true that not all the major search engines will crawl and index
PDF, which is very important to keep in mind when trying to get them
listed by those search engines.

For internal search on your own server, though there is a lot of
software that can do this.  Try:

Numerous Products at PDF Zone
http://www.pdfzone.com/

For Microsoft Index Server users, iFilter is what allows indexing of
files like PDF
http://www.microsoft.com/ntserver/search/ifdocdl.htm

I've also done a fair bit of research on software that supports PDF,
which I can share with anyone who's interested.

It should be noted, though, that PDF isn't going to magically become
text if it's derived from an analog original.  Both PDF and TIFF will
require some work to convert their "text as image" into "text as text".
To a computer, a bitmap is radically different from a stream of ASCII
text.

* Integrity of the original

TIFF and PDF are also often pretty similar on this front.  In some
cases, PDF is sometimes EASIER to alter, when its text is represented as
text (and please don't tell me that those with malicious intentions
won't bother to pick up some software from Adobe), whereas TIFF page
images are always just images, which can be altered though a graphic
editor but only with a lot of difficulty.

The literature has been telling us for many years, though, that
reliability and authenticity of electronic records depends on a
recordkeeping SYSTEM, not the inherent qualities of a specific
electronic file.  If you don't trust the system, you can't trust the
record.  Period.  The Minnesota work on Trustworthy Information Systems
http://www.mnhs.org/preserve/records/tis/tis.html
is a very valuable contribution to the ongoing conversation about how to
ensure this.

The Victorian Electronic Records Strategy (VERS) work that recommends
PDF also discusses recordkeeping system issues at length.  I don't think
anyone can say with a straight face that a PDF file on its own can
somehow prove its own authenticity.  Even authentication with a digital
signature, which can be done with PDF, raises another of systematic
issues.  If you don't trust the various components of the public-key
infrastructure associated with that signature (public keys, private
keys, encryption algorithms, certificates, certificate revocation lists,
certification policies, audit trails for records that have been
converted since signed), there's no real reason to trust it either.

* Format for record creation

The sad fact is that we're often forced to deal with records that must
be converted from other proprietary formats or digitized from paper,
despite the fact that the majority of recent records were "born
digital."  If we want less proprietary records, then we have to very
actively advocate the creation of records in less proprietary formats.
And helping record creators to manage them electronically, rather than
printing them out and then recreating their metadata electronically sure
wouldn't hurt either.

Conversion and migration almost always lose at least some of the
structural, administrative and contextual metadata associated with a
record.  I would much prefer a record created in XML to one created in
Access, reported out to ASCII, saved as Word, resaved as PDF and then
described in XML.

There's an important distinction to be made, though, between born
digital electronic records and those that have been digitized for
preservation and/or access.  The appropriate approach will often vary
widely from one to the other.

* Accessibility and usability

The Web is based on hypertext.  This means transparently jumping from
one chunk of text to another, based on interest, NOT on technical
details of implementation.  Every time a different application has to
pop up to read a file, that scenario is thrown out the window.  Add to
that the fact that hyperlinking out of PDF files is neither easy nor
widely adopted (especially for files that are supposed to serve as
official records so they can't be altered), and you've got a significant
drop in usability almost every time a PDF file is presented to the user.

Two of the most common ways to get to web pages are also through search
engines or links from an email message.  Jumping from a link right into
a PDF document can be quite disorienting, since it doesn't provide the
global navigation and other contextual indicates that a web page can
upon first viewing it.  As archivists, we're supposed to care about
provenance and context, and jumping directly into a document can often
lose both of those.

Another thing to keep in mind is that users with limited technical
skills and/or strong security permission controls on their machines may
not be able to install the Adobe software.  The "well, all you have to
do is figure out what the heck Adobe is, then click on the link, then
read the instructions, then download the software, then install it, then
remember why the heck you downloaded it in the first place..."
explanation has serious limitations.

I agree that the public documentation of the PDF format - for version
1.3, see
http://www.pdfzone.com/resources/pdfspec13.html
of course you'll need Adobe to read it :-(
is extremely valuable.  But is important to note that PDF is a
proprietary format that depends on one vendor for its ongoing support
and maintenance.  And Adobe could even conceivably demand license fees
at some point (though there's not much indication they'll be doing that
any time soon).  I don't think this rules it out in all cases by any
means.  But it's one factor to consider.

There are also concerns about files for users with disabilities.  I
won't get into the technical details, but they're tied primarily to the
ability for screen reader software to read PDF reliably.  Of course, if
your alternative is just a page image in TIFF, GIF, or whatever, then
you'll have a lot of the same concerns.  And Adobe has documentation on
their efforts to address this issue
http://access.adobe.com/
but it's still very much worth considering.  If the choice is between
HTML and PDF, for example, HTML is almost always more accessible.

* Viewing and downloading through a browser

The major browsers can't read TIFF or PDF.  Both require other
supporting software.  As I stated earlier, TIFF can be converted to GIF
on the fly, if that's your preference.  If you're concerned about the
download speed of JPEG page images, I recommend you seriously consider
saving them as GIF.  GIF is much better at compressing bitonal images
like black text on white than is JPEG. Whereas highly compressed JPEG
will be much smaller for photographs and other images that have a lot of
color gradations.

Master TIFF files, which should usually be stored uncompressed will
always be huge.  That's just a price to pay for preserving them.  This
doesn't mean, though, that web users should have to download massive
uncompressed TIFF files.  That what JPEG and GIF are for (and, as I
mentioned before, most likely soon SVG and JPEG2000).

=======================================================
Cal Lee
Electronic Records Project Archivist
Kansas State Historical Society
Phone: 785-272-8681, ext. 280         Fax: 785-272-8682
http://da.state.ks.us/itab/erc/
http://www.kshs.org/archives/recmgt.htm
                  "Obsolete power corrupts obsoletely."
                                           - Ted Nelson

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