Sustainability of Digital Formats: Planning for Library of Congress Collections

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PDF/A-1a, PDF for Long-term Preservation, Use of PDF 1.4, Level A Conformance

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name ISO 19005-1. Document management - Electronic document file format for long-term preservation - Part 1: Use of PDF 1.4, Level A Conformance (PDF/A-1a)

Part 1 of the PDF/A ISO standard [ISO 19005-1:2005] 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. Level A conformance (PDF/A-1a) indicates complete compliance with the ISO 19005-1 requirements, including those related to structural and semantic properties of documents. Level B conformance (PDF/A-1b) indicates minimal compliance to ensure that the rendered visual appearance of a conforming file is preservable over the long term.

See PDF/A-1.

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_family, Portable Document Format
    Subtype of PDF_1_4, PDF 1.4
    Subtype of PDF/A-1, PDF for Long-term Preservation, Use of PDF 1.4

Local use Explanation of format description terms

LC experience or existing holdings See PDF/A-1.
LC preference See PDF/A-1.

Sustainability factors Explanation of format description terms

Disclosure See PDF/A-1.
    Documentation See PDF/A-1.
Adoption See PDF/A-1.
    Licensing and patents See PDF/A-1.
Transparency See PDF/A-1.
Self-documentation See PDF/A-1.
External dependencies See PDF/A-1.
Technical protection considerations See PDF/A-1.

Quality and functionality factors Explanation of format description terms

Normal rendering See PDF/A-1.
Integrity of document structure

PDF/A-1a requires representation of the logical structure of the document as specified in section 6.8 of ISO 19005-1. The standard recommends that creators "should attempt to capture a document's logical structure hierarchy to the finest granularity possible." Nevertheless, the standard also indicates that "PDF/A-1 writers should not add structural or semantic information that is not explicitly or implicitly present in the source material solely for the purpose of achieving conformance." Hence, the logical structure of a document will only be represented to the degree the creator or process during creation takes steps to incorporate relevant structural tagging.

In practice, many PDF/A-1a files are not tagged to support accessibility. See Accessibility: What PDF/A-1a Really Means, an article from 2010. The PDF/UA standard for PDF Enhancement for Accessibility was initially developed as a set of additional requirements above those included in PDF/A-1a, although by the time it became a standard, it was specified as extra requirements on PDF 1.7 (ISO 32000-1) and thus closer to PDF/A-2a.

Integrity of layout and display See PDF/A-1.
Support for mathematics, formulae, etc. See PDF/A-1.
Functionality beyond normal rendering Level A conformance with PDF/A-1 requires that images have alternate text descriptions. The natural language in which the document is written must be declared, and sections of text in other languages explicitly marked using an internal mechanism defined for PDF 1.4. Also see PDF/A-1.

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_family.
Magic numbers See related format.  See PDF/A-1.
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-1a file should have the integer value 1 for pdfaid:part and the value "A" for pdfaid:conformance.
Pronom PUID fmt/95
See for PDF/A-1a.
Wikidata Title ID Q26541013
See for PDF/A-1a.

Notes Explanation of format description terms

General See PDF/A-1.
History See PDF/A-1.

Format specifications Explanation of format description terms

Useful references


Last Updated: 10/12/2020