PDF Standards

Editor’s Note: This article has been updated now to show the latest PDF ISO Standards.

Years ago when we used to talk about PDF as being the most prominent document format, we’d always have to add a quick, under-the-breath, ‘de-facto standard’.

Yes, PDF was the document format most frequently chosen by system developers, enterprise specialists, print production gurus and all-round general purpose users in solving their document ‘use case’ scenarios. You can verify this by simple searches on Google for the number of documents of different file-types that exist.

  • PDF rates in at 3,440,000,000 – 98.39% (formerly 329,000,000 at 87% in 2009)
  • XPS at 42,300,000 – 1.21% (formerly 11,900 at ~0% in 2009)
  • DOC at 914,000,000 – 0.40% (formerly 48,100,000 at 12.75% in 2009) – total 377,111,900

But when it came to being 100 per cent assured that it would be around in years to come, well, it’s always been a case of biting our collective lips and hoping for the best. Yep, while PDF was highly entrenched, used and worshipped by millions, there was always that niggling thought about what we would do if Adobe pulled the plug? Maybe we should use ASCII text instead?

Well, that was then but over the past seven (formerly two years!), it’s been nothing but standards, standards, standards when it comes to PDF. In fact, there are so many that it’s very easy to lose track of what they are, and why or where you’d bother to use them.

PDF (AKA ISO 32000:1-2008)

July 1, 2008 was D-day, the date from which it was officially described as an ISO standard. This meant that PDF was not only an extremely popular format, but going forward, the ISO will be responsible for updating and developing future versions of the PDF specification.

This serves two very important purposes: a) it reinforces Adobe’s commitment to open standards, which in turn satisfies the growing desires and requirements of government departments and large organizations, and b) it effectively combats potential competitors such as XPS, which Microsoft was trying to fast track through a similar standardization process.

PDF/A (AKA ISO 19005-1:2005)

PDF/A was developed by Adobe Systems, NPES and AIIM International for a very specific purpose: the (very) long-term storage of documents. Based on version 1.4 of the PDF Specification, PDF/A is a very restricted and controlled subset of PDF. It is intended to ensure that archived documents can be opened in the very distant future — we’re talking 30-50 years, if not longer. This means that certain features of the main PDF specification are disallowed, as they may prevent someone in the future from opening and experiencing the document as intended by the document’s creator. Restricted features include things like JavaScript, audio and video content, encryption, etc.

If the ancient Egyptians could have had a standard to use instead of their stone tablets and parchments, then it would be PDF/A. It’s the sort of thing that archivists salivate over. It means that they no longer have to rely on the privately controlled TIFF format, which was inadequate for the long-term archiving of documents. TIFF is an image format like a photograph of the page, and cannot be searched for text (without performing OCR). Archivists can now put their energy into implementing workflows based around PDF/A documents.

This is a list of a few businesses, universities and governments around the world that have adopted PDF/A as part of their archival strategy:

  • The US National Archives and Records Administration (NARA)
  • The Swedish National Archives
  • DeepBlue (University of Michigan’s institutional repository)
  • International Organization for Standards (ISO)
  • The Federal Chamber of Architects and Engineering Consultants in Austria
  • The Norwegian Government
  • Potsdam University


While PDF/UA is not an official standard yet, it is hoped that it will eventually be defined to ensure PDFs are created in accessible way. A PDF/UA compatible file would specifically address the areas of universal accessibility (that’s what the UA standards for). This means that PDF/UA will target authoring, remediation and validation of PDF content to see that it’s suitable for use with assistive technologies.

You can already see some attempts by Adobe to assist in this area by way of the Read Out Loud features built into newer versions of the Adobe Reader (see View, Read Out Loud in Adobe Reader 7 or higher).

PDF/E (AKA ISO 24517-1:2008)

If you get your kicks and giggles from working all day with 3D drawings and animations then PDF/E is for you. It targets those working in the areas of engineering and CAD. Back in the early 2000s PDF came under fire from the engineering community because of its perceived poor performance when rendering large and complex engineering drawings — not to mention its lack of support for 3D drawings. In response to these criticisms, the PDF Engineering (PDF/E) Working Group was setup to tackle the task of building on the existing PDF specification to come up with an open standard that could be used by the engineering community for creating, exchanging and reviewing large-format documentation. This standard was intended to address key issues in the areas of large-format drawings, multimedia, form fields and rights management — to name a few — that might prevent the engineering community from embracing PDF in their workflows.

PDF/X (AKA ISO 15929:2002 or ISO 15930)

Plain old PDF can be used for all sorts of purposes, whether it be for simple electronic ‘hard-copies’ of webpages and emails or a format for real-time review and commenting. When it comes to high-end print production, however, PDF/X is what you want. It was first engineered in 2001, and acts as the umbrella to define all other PDF/X related standards. These include, PDF/X1-a, PDF/X-2 and PDF/X-3, to name a few.

PDF/X facilitates graphics exchange, but what that really means is that PDF/X umbrella defines strict rules for how PDF files should be composed when being used for high-end print production. Printers, and people sending PDFs to the printers, need to have confidence that the PDF they were sending or printing was created in a way that would ensure accurate results when printed. Fonts need to be embedded, the right color space has to be used, no encryption is permitted, the correct color profile needs to be included, and so on.

Here’s what they are, as defined by Wikipedia (updated 2017):

ISO 15930 defines the specific implementations:

  • ISO 15930-1: PDF/X-1a:2001, Blind exchange in CMYK + Spot Colors, based on PDF 1.3
  • ISO 15930-7:2010: Graphic technology — Prepress digital data exchange using PDF — Part 7: Complete exchange of printing data (PDF/X-4) and partial exchange of printing data with external profile reference (PDF/X-4p) using PDF 1.6
  • ISO 15930-1:2001: Graphic technology — Prepress digital data exchange — Use of PDF — Part 1: Complete exchange using CMYK data (PDF/X-1 and PDF/X-1a)
  • ISO 15930-3:2002: Graphic technology — Prepress digital data exchange — Use of PDF — Part 3: Complete exchange suitable for colour-managed workflows (PDF/X-3)
  • ISO 15930-4:2003: Graphic technology — Prepress digital data exchange using PDF — Part 4: Complete exchange of CMYK and spot colour printing data using PDF 1.4 (PDF/X-1a)
  • ISO 15930-6:2003: Graphic technology — Prepress digital data exchange using PDF — Part 6: Complete exchange of printing data suitable for colour-managed workflows using PDF 1.4 (PDF/X-3)
  • ISO 15930-8:2010: Graphic technology — Prepress digital data exchange using PDF — Part 8: Partial exchange of printing data using PDF 1.6 (PDF/X-5)

That’s it for now…

All in all, it’s been a long road since the early days of John Warnock’s Camelot paper (the original document which detailed the idea of PDF), but yes, PDF has finally matured. It is no longer a de-facto standard used when and why it seemed appropriate. Nope, PDF is a big boy now, and has made a bona-fide entry into the world of: basic print replacement, review and comment, document exchange, long-term archival, integration with assistive technologies, engineering and CAD — and of course, high-end print production.

Who knows what is yet to come, but you can guarantee that with the increasing number of offices shifting some part of their operations onto the Internet, PDF will certainly continue to play an active role.

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About the Author: Karl De Abrew

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