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Format

Acrobat PDF/A - Portable Document Format

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Summary

Name
Acrobat PDF/A - Portable Document Format
Version
3a
Identifiers
  • MIME: application/pdf
  • PUID: fmt/479
Format type
Page Description
Description
The Portable Document Format/Archive is a format designed for long term preservation by Adobe Systems. PDF/A is an ISO standardised version of PDF, with all of the features from PDF that would impede long term preservation removed. A major principle of PDF/A is that it is self contained and not reliant on externalities thus all font and colour information is encoded into the file. PDF/A files are larger than other types of PDF files due to the need for embedded information. PDF/A3 supports three levels of compliance: PDF/A-3a (Accessible), PDF/A-3b (Basic). and PDF/A-3u (Unicode). The PDF/A-2 standard is a constrained subset of ISO 32000-1 (PDF 1.7), which includes PDF 1.0-1.7 and is defined by ISO 19005-3:2012, which has the formal name 'Document management - Electronic document file format for long-term preservation - Part 3: Use of ISO 32000-1 with support for embedded files (PDF/A-3)'. The primary new feature in PDF/A-3 is the ability to embed any source format within a PDF/A file.
File extensions
pdf
Source
Digital Preservation Department / The National Archives

Relationships

Has priority over
Is subtype of

Internal signatures

PDF/A-3A

Note
BOF: %PDF1.(0-7) VAR: Identifies the byte sequence which equals - xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/ which is the PDF/A identification namespace within the PDF/A meta-data, followed by <pdfaid:part>3<pdfaid:part> and <pdfaid:conformance>A<pdfaid:conformance>, which are the two mandatory elements and values for PDF/A. See ISO 19005-3:2012 for further information.

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
144
Byte Sequence
255044462D312E[30:37]
Endianness
None
Min Frag Length
Variable
Offset
None
Max offset
None
Byte Sequence
786D6C6E733A7064666169643D(22|27)687474703A2F2F7777772E6169696D2E6F72672F706466612F6E732F6964*7064666169643A70617274(3D22|3D27|3E)33(22|27|3C2F7064666169643A706172743E){0-120}7064666169643A636F6E666F726D616E6365(3E|3D22|3D27)41(22|27|3C2F7064666169643A636F6E666F726D616E63653E)
Endianness
None

PDF/A-3A 2

Note
BOF: %PDF1.(0-7) VAR: Identifies the byte sequence which equals - xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/ which is the PDF/A identification namespace within the PDF/A meta-data, followed by <pdfaid:part>3<pdfaid:part> and <pdfaid:conformance>A<pdfaid:conformance>, which are the two mandatory elements and values for PDF/A. See ISO 19005-3:2012 for further information.

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
144
Byte Sequence
255044462D312E[30:37]
Endianness
None
Min Frag Length
Variable
Offset
None
Max offset
None
Byte Sequence
786D6C6E733A7064666169643D(22|27)687474703A2F2F7777772E6169696D2E6F72672F706466612F6E732F6964*7064666169643A636F6E666F726D616E6365(3E|3D22|3D27)41(22|27|3C2F7064666169643A636F6E666F726D616E63653E){0-120}7064666169643A70617274(3D22|3D27|3E)33(22|27|3C2F7064666169643A706172743E)
Endianness
None

Changelog

  • Added in V101

    Release date
    15 February 2022

    Acrobat PDF/A - Portable Document Format (3a): Additional signature added to allow for PDF conformance and PDF part tags to be alternated. Extension to BOF offset and 0-120 byte gap between part and conformance tags added to original signature. Submitted by The National Archives of the Czech Republic.

    Acrobat PDF/A - Portable Document Format (3a): Signature researched and samples provided by The National Archives of the Czech Republic.

  • Updated in V89

    Release date
    8 March 2017

    Acrobat PDF/A - Portable Document Format 3a: Adjusted description due to suggestion of Yan Han, the University of Arizona Libraries and Leonard Rosenthol, Adobe Systems

  • Updated in V88

    Release date
    27 September 2016

    Acrobat PDF/A - Portable Document Format 3a: Gave priority over x-fmt/453 - TrueType Font. Suggested by Archives New Zealand.

  • Updated in V81

    Release date
    18 February 2015

    Acrobat PDF/A 3a: MIME Type added. Submitted by Docuteam.

  • Updated in V74

    Release date
    31 March 2014

    Acrobat (PDF/A) Portable Document Format 3a: Increased flexibility of VAR signature sequence.

  • Added in V65

    Release date
    25 October 2012

    Acrobat PDF/A-3a - Portable Document Format: Signature developed through PRONOM Research with assistance from Koninklijke Bibliotheek.

    Acrobat PDF/A-3a - Portable Document Format: Outline Entry Added.