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Format

Acrobat PDF/A - Portable Document Format

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Summary

Name
Acrobat PDF/A - Portable Document Format
Version
1a
Identifiers
  • MIME: application/pdf
  • Apple Uniform Type Identifier: com.adobe.pdf
  • PUID: fmt/95
Format type
Page Description
Disclosure
Full
Description
The Portable Document Format/ Archive is a format designed for long term preservation by Adobe Systems. PDF/A is a simplified version of PDF 1.4, with all of the features from PDF 1.4 that would impede long term preservation removed. Removed features include Javascript, Audio/Visual content, LZW compression and encryption. 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/A supports two levels of compliance PDF/A1-a (Accessible) and PDF/A1-b (Basic). PDF/A1-a is fully ISO 19005-1:2005 (PDF/A-1) compliant whereas PDF/A1-b is less stringent and not compliant. PDF/A1-a requires tagged PDF and Unicode whereas PDF/A1-b does not.
Release date
01 Oct 2005
Format encoding
Binary
File extensions
pdf
Submitted by
Digital Preservation Department / The National Archives

Relationships

Has priority over

Internal signatures

Acrobat PDF/A-1a

Description
Describes a signature for the PDF/A-1a form. 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>1<pdfaid:part> and <pdfaid:conformance>A<pdfaid:conformance>, which are the two mandatory elements and values for PDFA/1a. See ISO 19005-1:2005 and Technical Corrigendum 1 for further information.
Provenance
Ongoing Digital preservation research.

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
144
Byte Sequence
255044462D312E[30:37]
Endianness
Little-endian
Min Frag Length
Variable
Offset
None
Max offset
None
Byte Sequence
786D6C6E733A7064666169643D(22|27)687474703A2F2F7777772E6169696D2E6F72672F706466612F6E732F6964*7064666169643A70617274(3D22|3D27|3E)31(22|27|3C2F7064666169643A706172743E){0-120}7064666169643A636F6E666F726D616E6365(3E|3D22|3D27)41(22|27|3C2F7064666169643A636F6E666F726D616E63653E)
Endianness
Little-endian

PDF/A-1A 2

Description
Describes a signature for the PDF/A-1a form. 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:conformance>A<pdfaid:conformance>and <pdfaid:part>1<pdfaid:part>, and which are the two mandatory elements and values for PDFA/1a. See ISO 19005-1:2005 and Technical Corrigendum 1 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)31(22|27|3C2F7064666169643A706172743E)
Endianness
None

Changelog

  • V103

    Release date
    11 March 2022

    • Updated

      Acrobat PDF/A - Portable Document Format (1a): Update to signature following error. Removal of whitespace causing issues in FIDO. Submitted by Vanderbilt University, Preservica and Misty De Méo.

  • V101

    Release date
    15 February 2022

    • Added signature

      Acrobat PDF/A - Portable Document Format (1a): Signature researched and samples provided by The National Archives of the Czech Republic.

    • Updated

      Acrobat PDF/A - Portable Document Format (1a): 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.

  • V89

    Release date
    8 March 2017

    • Updated

      Acrobat PDF/A - Portable Document Format 1a: Adjusted signature due to findings by Koninklijke Bibliotheek

  • V88

    Release date
    27 September 2016

    • Updated

      Acrobat PDF/A - Portable Document Format 1a: Gave priority over x-fmt/453 - TrueType Font as suggested by Archives New Zealand. Additionally gave priority over Acrobat PDF - Portable Document Format versions 1.0-1.7 due to clash identified by Docuteam.

  • V81

    Release date
    18 February 2015

    • Updated

      Acrobat PDF/A 1a: MIME Type added. Submitted by Docuteam.

  • V74

    Release date
    31 March 2014

    • Updated

      Acrobat (PDF/A) Portable Document Format 1a: Increased flexibility of VAR signature sequence.

  • V51

    Release date
    15 July 2011

    • Updated

      Acrobat PDF/A - Portable Document Format 1a: Existing signature refined following request from Archaeology Data Service and record title updated to distinguish different versions.

The National Archives is not responsible for the contents available at the following links

Library Of Congress