Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
|
|
|
|
| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | ISO 19005-1. Document management - Electronic document file format for long-term preservation - Part 1: Use of PDF (PDF/A) |
| Description | PDF/A-1 is a constrained form of Adobe PDF version 1.4 intended to be suitable for long-term preservation of page-oriented documents for which PDF is already being used in practice. The ISO standard [ISO 19005-1:2005] was developed by a working group with representatives from government, industry, and academia and active support from Adobe Systems Incorporated. Part 2 of ISO 19005 will be a version of PDF/A based on a more recent version of PDF. PDF/A attempts to maximize: • Device independence • Self-containment • Self-documentation The constraints include: • Audio and video content are forbidden • Javascript and executable file launches are prohibited • All fonts must be embedded and also must be legally embeddable for unlimited, universal rendering • Colorspaces specified in a device-independent manner • Encryption is disallowed • Use of standards-based metadata is mandated |
| Production phase | A final-state format for delivery to end users and long-term preservation of the document as disseminated to users. |
| Relationship to other formats | |
| Subtype of | PDF (Portable Document Format) |
| Subtype of | PDF_1_4 |
| Has subtype | PDF/A-1a |
| Has subtype | PDF/A-1b |
| LC experience or existing holdings | LC is represented on the working group for the standard. |
| LC preference | PDF/A is suggested as a preferred format for page-oriented textual (or primarily textual) documents when layout and visual characteristics are more significant than logical structure. Note that, for PDFs based on page images digitized by scanning, the source images are considered the master format if available and PDFs created from those images may be optimized for access convenience. |
| Disclosure | Open standard, approved in May 2005 and published by ISO in September 2005. Developed by the working group ISO/TC 171 SC2, Document Imaging Applications, Application Issues, for which AIIM (The Association for Information and Image Management) acts as secretariat. ISO has formed a Joint Working Group, which also includes ISO/TC 46 SC11, Archives/records Management, ISO/TC 130, Graphics Technology, and ISO/TC 42, Photography. |
| Documentation | ISO 19005-1:2005. Document management -- Electronic document file format for long-term preservation -- Part 1: Use of PDF 1.4 (PDF/A-1). The standard cannot be used without PDF Reference, Third Edition, Version 1.4, which it uses as a normative reference. |
| Adoption | Since the standard was published in late 2005, tools for creation, conversion, and validation have been reachign the market steadily. Adobe's own Acrobat Professional 7.0 allowed saving files in a form compliant with the draft standard. Acrobat 8 supports the standard as published. During 2006, several commercial companies with products aimed at large enterprises, produced products supporting the creation, migration, and validation of PDF/A files: Apago, Inc., Visioneer (for scanning paper to PDF/A), Callas Software, Compart Systemhaus, Luratech, Nuance, PDF Tools AG, Many of these companies are based in Europe, where the growing requirements from the EU for use of digital formats that are formal (preferably ISO) standards has produced more market pressure than in the U.S. Version 0.93 of the widely used open source FOP (Formatting Object Processor, based on the W3C's XSL-FO standard) from Apache (released in January 2007), has support for the minimal PDF/A profile, PDF/A-1b. The standards development process involved active participation on behalf of communities whose endorsement or adoption would create significant momentum for wider adoption in the sense of requirement or preference for PDF/A over generic PDF for archival deposit or submission. Important groups are government agencies and legislative and judicial institutions. Adobe reported migration of legacy "report silos" at several (un-named) financial institutions at a meeting of the European DLM (Document Lifecycle Management) Forum in Helsinki in November 2006. |
| Licensing and patent claims | Not expected to be a problem, but not investigated at this time. The standard includes ISO boilerplate text indicating "the possibility that some of the elements of this document may be the subject of patent rights." |
| Transparency | Depends upon compliant software tools to read. Building tools requires sophistication. PDF/A does not permit encryption. |
| Self-documentation | Support for embedding any form of metadata for a document is extremely good. Use of XMP is mandatory for basic descriptive and identifying metadata. Other XMP metadata packages can be embedded. |
| External dependencies | PDF/A is constrained to avoid external dependencies. All necessary fonts must be embedded. |
| Technical protection considerations | PDF/A does not permit encryption. |
| Normal rendering for text | Good support is possible, but not guaranteed. The PDF/A format does not preclude creating documents from scanned page images; such files do not necessarily support indexing of the document text or extraction of text for quotation. |
| Integrity of structure | The logical structure of a document is only represented in a PDF/A file if the creator or process during creation takes steps to incorporate structural tagging. The PDF/A standard recommends the representation of structural hierarchy |
| Integrity of layout | PDF is designed to represent the layout of page-oriented documents. |
| Integrity of rendering of equations, etc. | Can be represented by embedded graphics. |
| Beyond normal rendering | Annotations may be embedded. Bookmarks may be provided. |
| Tag type | Value | Note |
| Filename Extension | The standard does not indicate that a different extension should be used to distinguish PDF from PDF/A. | |
| Internal Identification | The standard specifies that the PDF/A version and conformance level of a file shall be specified using the PDF/A Identification extension schema defined in the standard. This schema has two mandatory elements: pdfaid:part (integer) and pdfaid:conformance (closed list of text values). A PDF-1 file should have the integer value 1 for pdfaid:part. |
| General | The PDF/A standard is aligned to the fullest extent possible with the PDF/X standard. |
| History | Developed to address the issue that large bodies of official documents
and important information are maintained in PDF, but that PDF is not suitable
as an archival format. The Administrative Office of the U.S. Courts was
a driving force in forming a U.S. Committee to initiate an ISO standard
based on PDF. The activity has been under the joint auspices of AIIM and
NPES (National Printing Equipment Suppliers).
As of January 2007, a new version of the PDF/A standard is under development, to be based on PDF 1.6 (or PDF 1.7). |
URLs
• ISO 19005-1:2005. Document management -- Electronic document file format for long-term preservation -- Part 1: Use of PDF 1.4 (PDF/A-1) (http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=38920)
• Draft International Standard. DIS ISO/CD 19005-1. Document management - Electronic document file format for long-term preservation - Part 1: Use of PDF (PDF/A) (http://www.archivists.org.au/pubs/ISO_DIS_19005-1.pdf)
Print
• Adobe Systems Incorporated. PDF Reference, Third Edition, Version 1.4. Addison-Wesley, 2001. ISBN 0-201-75839-3. Also available online as http://partners.adobe.com/public/developer/en/pdf/PDFReference.pdf.
URLs
• PDF-Archive Web site at AIIM (http://www.aiim.org/standards.asp?id=25013)
• ISO 19005-1 Frequently Asked Questions at AIIM (http://www.aiim.org/documents/standards/19005-1_FAQ.pdf) or NPES (http://www.npes.org/standards/Tools/19005-1_FAQ.pdf)
• PDF/A Competence Center (http://www.pdfa.org/doku.php)
• Guidelines for Creating Archival Quality PDF Files from Florida Center for Library Automation (http://www.fcla.edu/digitalArchive/pdfs/PDFGuideline.pdf)
• PDF/A — Format — Status and Practical Experiences. Presentation at the European Document Lifecycle Management (DLM) Forum in November 2006, by Marc Straat, Head of Standards Development Europe, Adobe Systems Europe Limited (www.aiimhost.com/DLM/DLMHelsinki_MarcStraat.pdf)
|
|