The Library of Congress Prefers PDF/UA for WCAG 2.0 compliance in archival content

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The Sustainability of Digital Formats project names PDF/UA as preferred to PDF/A alone for archiving accessible electronic documents.

The Library of Congress (LoC) National Digital Information Infrastructure and Preservation Program operates the Sustainability of Digital Formats program for the Library of Congress as part of Goal 2 of its Strategic Plan (link goes to an untagged PDF, tsk tsk).

The program has several purposes including: sustainability

  • Support for LoC strategic planning regarding long term planning considerations for document and other formats
  • Assessing current and emerging formats and tools needed to ensure management of content created or received in these formats
  • To identify, evaluate and help sustain formats promising for archival needs; and to describe formats that are not promising for long-term sustainability, and strategies to address such cases

The scope of the LoC’s Goal 2 includes, generally, the public benefit of accessibility, and accordingly, the program reviewed PDF/UA, the new international standard for accessible PDF files and PDF software.

More precisely, the Digital Preservation Program reviewed “ISO 14289-1. Document management applications – Electronic document file format enhancement for accessibility – Part 1: Use of ISO 32000-1” – the formal name for PDF/UA.

As the LoC describes it, PDF/UA, it is a limited (constrained) subset of the PDF format. PDF/UA includes a number of strict requirements for conforming files. The Sustainability of Formats project is focused (obviously) on sustainability rather than accessibility. It is interesting, nonetheless, that the entry on PDF/UA is the only occasion in which the possibility of WCAG conformance is mentioned on the project’s website.

The entry on PDF/UA states: “Requirements for PDF/UA compliance are consistent with the Web Content Accessibility Guidelines (WCAG) 2.0, a W3C Recommendation from 11 December 2008.”

Unlike WCAG 2.0, PDF/UA goes beyond the file-format to set requirements for PDF/UA conforming reader and assistive technology (AT) software, but evaluation of this aspect of PDF/UA is outside the LoC program’s scope.

The program establishes Library of Congress preferences for PDF files created or submitted to the Library for their collection. As such, the program has long since identified PDF/A as a desirable format due to its approach regarding long-term sustainability.

With respect to PDF/UA, the LoC’s webpage on PDF/UA states:
“Since an unencrypted PDF document compliant with PDF/UA may also comply with requirements for PDF/A, files that conform to PDF/UA in addition to PDF/A are considered a preferred format for page-oriented content by the Library of Congress. See PDF/A. (emphasis added).”
Accordingly, tools that generate PDF/UA conforming files in addition to PDF/A are meeting the highest standards for archival electronic content. Such files offer the greatest potential for high-quality repurposing.

Having participated in developing the standard, NetCentric is hard at work on new releases of our Commonlook line of products that conform to PDF/UA. To learn more about how NetCentric’s plans for PDF/UA support, contact, or call your NetCentric representative.

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