A pattern was established in which poorly-structured PDF files were roaming around in the wild, and that problem has worsened over time. As PDF has grown more popular, more and more applications of widely varying quality make bad PDF.
Adobe's solution was to engineer Adobe Reader to handle all the various oddball PDF files out there. It's one of the main reasons why Adobe Reader is a larger application to download and install compared to its rivals. Reader includes lots of code to deal with the thousands of different types of exceptions to "good" PDF that Reader users worldwide can and will encounter on a regular basis.
In their attempt to ensure that even the sloppiest PDF files still worked, Adobe created a situation in which developers could (and have) used Adobe's Reader as the reference implementation for their PDF software.
In 2010, there is still no alternative to Adobe Reader when it comes to validating third-party software.
As the vice-chair of ISO 32000, that bothers me, and if you're relying on the idea that PDF is indeed an International Standard in your organization, it should bother you too.
Release the Validator!
To make the final move in ensuring PDF is a durable international standard, Adobe should release their test suite of PDF files used to test Adobe Reader. This could take form in several ways, the simplest of which would be a collection of PNG images demonstrating the authoritative rendering of example PDF pages.
This test suite should be referenced in the upcoming ISO 32000-2, the forthcoming update to the International Standard for PDF.
When this step is taken will it become possible to validate the open standard of ISO 32000 without the proprietary Adobe Reader, an objective which is fundamental to the project of PDF as an International Standard.
Establishing an open test suite will make PDF truly an open standard in the spirit of Warnock and Geschke's letter. The advantages for consumers will be substantial. Adobe and software developers can produce conversion software to resolve the old files.
With no further excuse for sloppy code, non-compliant software will tend to die away, removing a major source of problems.
PDF will become truly reliable and based not only on an international standard, but one that may be readily validated.
Adobe will have begun the process of liberating itself from supporting old (and now invalid) PDFs, and will eventually be free to re-direct engineering resources away from propping up other people's software and into creative development.
I can't imagine a world without PDF; if it didn't exist it would have to be invented. PDF is indeed an open standard, but it's incomplete. It's time to finish the story and end the practice of making Adobe Reader a de facto reference implementation.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.