Sustainability of Digital Formats: Planning for Library of Congress Collections |
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Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact |
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) |
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Description |
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) |
LC experience or existing holdings | See PDF/A_family. |
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LC preference | See PDF/A_family. |
Disclosure | See PDF/A-2. |
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Documentation | See PDF/A-2. |
Adoption |
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. |
Text | |
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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. |
Tag | Value | Note |
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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 https://www.nationalarchives.gov.uk/PRONOM/fmt/477 for PDF/A-2b. |
Wikidata Title ID | Q26546575 |
See https://www.wikidata.org/wiki/Q26546575 for PDF/A-2b. |
General | See PDF/A-2. |
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History | See PDF/A-2. |
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