Lessons from document archiving PDF/A Dave McAllister, Director, Open Source and Standards Adobe Systems Incorporated. All Rights Reserved.

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1 Lessons from document archiving PDF/A Dave McAllister, Director, Open Source and Standards

2 Archiving Requirements: Live Repeat the current experience at some future time. Including active nature and that depends upon being able to provide a suitable execution environment in the future. Interactive and dynamic types More powerful computers and displays available New delivery mechanisms and devices invent new metaphors that move away from our more static paper-based ideas Digital Rights Management two-fold challenge obsolescence of new (emerging) types base technologies may become obsolete 2

3 Digital Documents have existed for some time PDF (1993) A comprehensive format for representing documents and forms High fidelity, high precision text layout with embeddable fonts High-end device independent, color managed graphics features Platform independent definition Interactive elements & content Multimedia & 3D Security & digital signatures That s great for the web, screen viewing, ebooks, etc. But what about people who just want reliable printing and/or archiving? 3

4 Digital Document Archive needs A document format that Conveys critical information Can be rendered accurately (predictable and consistent) Offers metadata support Standard schemas Custom Schemas Provenance, version, history, audit Can incorporate marginalia Notes, comments, mark ups Can be signed (tamper proof) Provides a definition of retrieval 4

5 Enter PDF/A PDF/A-1 (ISO 19005) Long term preservation of black and white and color compound documents as electronic data Combinations of character, raster, vector and other data Provisions for capturing semantic information Preservation and retrieval of appropriate metadata static paper ++ Annotations & Marginalia Metadata Signatures 5

6 PDF/A-1 Details More restrictive coding of PDF details Ensures less ambiguity when implementing Based on PDF 1.4 & PDF/X-3 All PDF/X-3 documents can potentially be minimally conforming PDF/A documents without any changes Reduces ambiguity between different vendor's implementations Removal of any complex or potentially confusing graphic concepts No transparency Limited colorspaces No Security/Encryption All data must be self-contained No external resources Fonts MUST be embedded(!!) Limited annotation support No movies and sounds No JavaScript Links are stored but not executed Metadata based on Adobe XMP Low level font requirements Matching font widths CharSet/CIDSet CMaps 6

7 Levels of Conformance Minimal Conformance (PDF/A-1B) Meet the standard/basic requirements Full Conformance (PDF/A-1A) Tagged PDF Improved searchability via Unicode mappings Comprehensive metadata recommendations Font data Document pedigree Audit trail 7

8 Not just File Format Viewer Requirements Color management Use of output intent No use of alternates (except for Spot & DeviceN) Specific handling of DeviceGray Font handling ALWAYS use embedded data Interactivity Annotations & form fields are non-interactive must use the stored appearance provide access to data/contents Hyperlinks are questionable 8

9 PDF-A/2 Remain focused on static paper metaphor No interactivity, 3D, multimedia, etc. Updated to reference ISO Ensure as close to 100% forward compatibility as possible A PDF/A-1 document SHOULD be also a valid PDF/A-2 document However, valid technical changes to ensure long term reliability were preferred over compatibility. Predominantly in the areas of fonts & metadata Continue to maintain compatibility with other ISO standards PDF/X-4 PDF/E-1 9

10 Some new and important features in A-2 (and A-3) Improved compression technology/smaller files JPEG2000 Compressed XRefs & Streams (aka Full Compression ) Transparency PDF Layers (aka Optional Content) Whatever you view on screen, must print! PDF Packages/Collections May only contain other PDF/A documents Digital signature enhancements Certified Documents Improved revocation checking PAdES (ETSI TS ) Compliance required Improved tagging/accessibility This is the only major change to PDF/A-3 Embedded files can be of any format 10

11 New work under consideration Archiving PDFs with embedded 3D Archiving of digitally signed PDFs Archiving of source material inside the PDF Secondary issues Archiving of documents of record Rich forms, such as those based on XFA or with embedded JavaScript Desire to archive the business logic with the values May or may not be digitally signed Archiving of video and audio embedded into PDF New features of ISO Portfolios, RichMedia, GIS, etc. 11

12 Summation The basic requirements for multimedia archiving mirror those for digital documents The scope of formats is wider The envelope of contents is substantially larger Documents themselves may be considered a form of media Arising complexity will exist as the envelope for documents encompasses media types No media type is entirely separate from any other 12

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