Sustainability of Digital Formats: Planning for Library of Congress Collections

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PDF/A-2b, PDF for Long-term Preservation, Use of ISO 32000-1 (PDF 1.7), Level B Conformance

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name ISO 19005-2. Document management - Electronic document file format for long-term preservation - Part 2: Use of ISO 32000-1 (PDF 1.7), Level B Conformance (PDF/A-2b)

Part 2 of the PDF/A ISO standard [ISO 19005-2:2010] is a constrained form of Adobe PDF version 1.7 intended to be suitable for long-term preservation of page-oriented documents for which PDF is already being used in practice. Level B conformance (PDF/A-2b) indicates minimal compliance to ensure that the rendered visual appearance of a conforming file is preservable over the long term. Level A conformance (PDF/A-2a) indicates complete compliance with the ISO 19005-2 requirements, including those related to structural and semantic properties of documents. Level U conformance represents Level B conformance with the additional requirement that all text in the document have Unicode equivalents.

See PDF/A-2.

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_7, PDF, Version 1.7 (ISO 32000-1:2008)
    Subtype of PDF/A-2, PDF for Long-term Preservation, Use of ISO 32000 (PDF 1.7)

Local use Explanation of format description terms

LC experience or existing holdings See PDF/A_family.
LC preference See PDF/A_family.

Sustainability factors Explanation of format description terms

Disclosure See PDF/A-2.
    Documentation See PDF/A-2.

The addition of support for JPEG2000 compression in PDF/A-2 has led to recommendations for use of PDF/A-2b when scanning from paper, because of reduction in file size. See, for example, How to Pick the Right Version of PDF/A from PDFtron, a company producing software tools to enable digital document processing capabilities in enterprise and commercial applications. In Digitization of Textual Documents Using PDF/A, Yan Han and Xueheng Wan describe their methodology, based on open source software, for converting page images scanned from historical materials as uncompressed TIFFs (see TIFF_UNC) to use JPEG 2000 compression (see J2K_C) and combine images for all pages in a document with page-level metadata into a single PDF/A-2b file. They were able to recover raster images with data streams identical to the original TIFFs. Based on their experience with over 600,000 page images, they argue that the resulting PDF/A-2b file has advantages as an archival master over the use of a set of separate TIFF or JPEG 2000 images.

See also PDF/A-2.

    Licensing and patents See PDF/A_family.
Transparency See PDF/A_family.
Self-documentation See PDF/A_family.
External dependencies See PDF/A_family.
Technical protection considerations See PDF/A_family.

Quality and functionality factors Explanation of format description terms

Normal rendering See PDF/A_family.
Integrity of document structure PDF/A-2b does not require representation of the logical structure of the document as specified in section 6.8 of ISO 19005-2.
Integrity of layout and display See PDF/A_family.
Support for mathematics, formulae, etc. See PDF/A_family.
Functionality beyond normal rendering See PDF/A_family.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension pdf
The standard does not indicate that a different extension should be used to distinguish PDF from PDF/A.
Internet Media Type See related format.  See PDF.
Magic numbers See related format.  See PDF.
Indicator for profile, level, version, etc. See note.  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 and pdfaid:conformance. A PDF/A-2b file should have the integer value 2 for pdfaid:part and the value "B" for pdfaid:conformance.
Pronom PUID fmt/477
See for PDF/A-2b.
Wikidata Title ID Q26546575
See for PDF/A-2b.

Notes Explanation of format description terms

General See PDF/A-2.
History See PDF/A-2.

Format specifications Explanation of format description terms

Useful references


Last Updated: 10/12/2020