The Coming of PDF 2.0 – Part 1

Artifex Engineering has been following developments in the PDF 2.0 (ISO 32000-2) specification from draft revisions of late 2016 to the final release publication in July 2017.  This is the first PDF specification from an ISO working group, instead of Adobe, and perhaps the most notable changes with PDF 2.0 are in the language of the specification itself.

In this article we will share some overall information with our customers and community regarding PDF 2.0. In Part 2 of this series we will provide some specific insights as to what it means for our products and our customers.

 

What is PDF 2.0?

PDF 2.0 is the next generation of the standard Portable Document Format. This is the first major update in the post-Adobe world of PDF. It’s been nine years since the previous update, PDF 1.7, became ISO 32000-1 in May 2008. While there are a lot of changes, they primarily affect developers, giving them clearer, cleaner direction for developing software that relies on PDF technology.

What’s Changed?

Every section of the specification has been completely rewritten with a focus on gaining an accurate and unambiguous description of all, mostly existing, features.  The PDF association describes PDF 2.0 as a “refinement” of PDF 1.7; there are a few new, updated and deprecated features, but the important changes are to more carefully specify what already existed in PDF version 1.7. The text of PDF 2.0 is significantly clearer and more consistent in terms of describing the various features, requirements and considerations in PDF technology.

Per the PDF Association, “PDF 2.0 addresses ambiguities, corrects errors and updates normative references … Although these changes don’t represent new features per se, they make it much easier to implement the specification. In short, PDF 2.0 will make it easier and less costly for developers to improve their support for PDF technology at every level.”

More Details

While the number of changes are too many to enumerate in a blog post, here are some of the major changes noted by the PDF Association.

New features in PDF 2.0 include

  • Unencrypted wrapper document
  • Numerous enhancements for print and rendering-related features
  • New annotation types to support projections, rich media, 3D annotations
  • Geospatial features
  • Navigators, to support graphical representation of embedded files
  • Major enhancements to digital signature technology
  • Associated files (introduced with PDF/A-3)
  • Enhanced encryption
  • Pronunciation hints
  • Tagged PDF has several new standard structure elements and attributes

Enhancements to existing features include

  • Transparency and blend mode attributes for annotations
  • Polygon/Polyline real paths
  • 256-bit AES encryption (added to PDF 2.0)
  • ECC-based certificates
  • Unicode-based passwords
  • Document requirement extensions
  • Page-level and Referenced (external) Output Intents
  • Thumbnails for embedded files
  • Measurement & Point Data for image & form XObjects
  • Viewer preferences enforcement (of print scaling)
  • GoToDp and RichMediaExecute actions
  • Extension to GoTo and GoToR to support linking to a specific structure element
  • Extension to Signature Field Locks and Signature Seed Values
  • 3D measurements, and extensions to 3D viewing conditions, incl. transparency
  • Several new structure elements, including Aside, DocumentFragment, Hn (where n > 6), Title, FENote, Sub, Em, Strong and Artifact structure elements
  • Extensions to OutputIntents (MixingHints and SpectralData)

Reorganization/rewriting of existing features

  • 10.1 – 10.3, “Rendering”
  • 11, “Transparency”
  • 12.8, “Digital signatures”
  • 14.3, “Metadata”
  • 14.8, “Tagged PDF”
  • 14.9, “Repurposing and accessibility support”

Deprecations

Several features from earlier PDF versions are declared as deprecated in PDF 2.0, and should therefore not be used when creating new PDF 2.0 documents. Per the PDF Association, “as features were modernized, the ISO committee elected to deprecate obsolete aspects to reduce the burden on implementers.” However, these features may still be supported in viewers for processing existing documents as well as PDF 2.0 documents which still contain them. Both PDFLib and the PDF Association have good listings of deprecated features. We recommend you visit these links for more detailed information on this subject.

That sums up basic information regarding PDF 2.0. We will be posting a second article shortly with our thoughts as to what this means for our products.