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Re: Australian Government guidance on PDF Accessibility

for

From: Duff Johnson
Date: Jan 5, 2011 5:54PM

On Jan 5, 2011, at 7:25 PM, Webb, KerryA wrote:

> Birkir wrote:
>
>> It also open the possibility for document alterations.
>>
>
> I hope you don't mind if I jump on this one; it's a pet peeve of mine.

Jumping? I LOVE jumping! :-)

> Some of our people insist on publishing in PDF because "it can't be altered". Often it's people who have to publish contracts or legislation.

C'mon, these aren't technical people we're talking about. They mean that PDF "can't be altered" in the sense that it's not a word-processing file. They're not making a technical claim about the degree of encryption, or lack thereof, in their PDFs.

Their belief is an understandable (if erroneous) extension of the basic truth of PDF (accessibility aside - for a moment!); that it's self-contained, and appears the same way to all users on all systems.

PDF files don't suffer the indignities of (for example) page-breaks getting screwed up when you send a DOC from A to B.

A simple way to rid users of their invalid assumptions about the inviolability of PDF is simply to ask them to send you one of their files. You then edit it in a dramatic way (say, remove every other line from the first para) and send it back to them 2 minutes later... all the while making the point that you're using commercial, off the shelf software that anyone can buy.

That usually does the trick.

> I don't buy this. You can do a lot with computers; you can even mock up a genuine-looking altered PDF, so that argument just won't wash.

Certainly, people believe all sorts of things - but it's nice to know when PDF can actually live up to the user's imagination. It's simply that it doesn't happen by magic.

A PDF file may be digitally-signed with a CA (Certificate Authority) providing authentication of the file's origin. The signature itself provides assurance to the end-user that the file has not been altered after application of the signature.

Here's one such example:

http://www.gpoaccess.gov/usbudget/fy11/pdf/budget.pdf

Try doing that with HTML. ;-)

Duff.