Document management -- Electronic document file format for long-term preservation

ISO 19005-3:2012 specifies the use of the Portable Document Format (PDF) 1.7, as formalized in ISO 32000-1, for preserving the static visual representation of page-based electronic documents over time in addition to allowing any type of other content to be included as an embedded file or attachment.

Gestion de documents -- Format de fichier des documents électroniques pour une conservation à long terme

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Status
Published
Publication Date
14-Oct-2012
Current Stage
6060 - International Standard published
Start Date
05-Oct-2012
Completion Date
15-Oct-2012
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INTERNATIONAL ISO
STANDARD 19005-3
First edition
2012-10-15
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)
Gestion de documents — Format de fichier des documents
électroniques pour une conservation à long terme —
Partie 3: Utilisation de l’ISO 32000-1 avec support de fichiers
incorporés (PDF/A-3)
Reference number
ISO 19005-3:2012(E)
ISO 2012
---------------------- Page: 1 ----------------------
ISO 19005-3:2012(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2012

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any

means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the

address below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2012 – All rights reserved
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ISO 19005-3:2012(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Notation ......................................................................................................................................................................................................................... 3

5 Conformance levels ............................................................................................................................................................................................ 4

5.1 General ........................................................................................................................................................................................................... 4

5.2 Level A conformance .......................................................................................................................................................................... 4

5.3 Level B conformance .......................................................................................................................................................................... 5

5.4 Level U conformance.......................................................................................................................................................................... 5

5.5 Conforming readers ............................................................................................................................................................................ 5

6 Technical requirements ................................................................................................................................................................................ 6

6.1 File structure ............................................................................................................................................................................................ 6

6.2 Graphics ........................................................................................................................................................................................................ 8

6.3 Annotations.............................................................................................................................................................................................17

6.4 Interactive forms ................................................................................................................................................................................18

6.5 Action ...........................................................................................................................................................................................................19

6.6 Metadata ....................................................................................................................................................................................................19

6.7 Logical structure .................................................................................................................................................................................24

6.8 Embedded files ....................................................................................................................................................................................26

6.9 Optional content .................................................................................................................................................................................27

6.10 Use of alternate presentations and transitions ........................................................................................................28

6.11 Document requirements ..............................................................................................................................................................28

Annex A (normative) Method for determining transparency on a page ......................................................................29

Annex B (normative) Requirements for digital signatures in PDF/A .............................................................................31

Annex C (informative) Best practices for PDF/A ...................................................................................................................................32

Annex D (informative) Incorporation of XFA data sets ...................................................................................................................34

Annex E (normative) Associated files ...............................................................................................................................................................35

Bibliography .............................................................................................................................................................................................................................41

© ISO 2012 – All rights reserved iii
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ISO 19005-3:2012(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International

Standards adopted by the technical committees are circulated to the member bodies for voting.

Publication as an International Standard requires approval by at least 75 % of the member bodies

casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 19005-3 was prepared by Technical Committee ISO/TC 171, Document management applications,

Subcommittee SC 2, Application issues, in cooperation with ISO/TC 130, Graphic technology, ISO/TC 42,

Photography, and ISO/TC 46, Information and documentation, Subcommittee SC11, Archives/records

management.

ISO 19005 consists of the following parts, under the general title Document management — Electronic

document file format for long-term preservation:
— Part 1: Use of PDF 1.4 (PDF/A-1)
— Part 2: Use of ISO 32000-1 (PDF/A-2)
— Part 3: Use of ISO 32000-1 with support for embedded files (PDF/A-3)
iv © ISO 2012 – All rights reserved
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ISO 19005-3:2012(E)
Introduction

PDF is a digital format for representing page-based documents. PDF files can be created natively in PDF

form, converted from other electronic formats or digitized from paper, microform, or other hard copy

format. Businesses, governments, libraries, archives and other institutions and individuals around the

world use PDF to represent considerable bodies of important information. Much of this information

needs to be kept for substantial lengths of time; some needs to be kept permanently. These PDF files

need to remain useable and accessible across multiple generations of technology. However, the inclusive,

feature-rich nature of the format requires that constraints be placed on its use to make it suitable for the

long-term preservation of electronic documents. The future use of, and access to, these objects depends

upon maintaining their visual appearance as well as their higher-order properties, such as the logical

organization of pages, sections, and paragraphs, machine recoverable text stream in natural reading

order, and a variety of administrative, preservation and descriptive metadata.

This International Standard is created as a multi-part document, of which this is part 3. This allows future

parts to be created without rendering this document or applications based on this document obsolete.

The primary purpose of ISO 19005 is to define a file format based on PDF, known as PDF/A, which provides a

mechanism for representing electronic documents in a manner that preserves their static visual appearance

over time, independent of the tools and systems used for creating, storing or rendering the files.

A secondary purpose of ISO 19005 is to define a framework for representing the logical structure and

other semantic information of electronic documents within conforming files.

Another purpose of ISO 19005 is to provide a framework for recording the context and history of

electronic documents in metadata within conforming files.

This part of ISO 19005 adds a new goal (beyond that of ISO 19005-2) which is to enable PDF documents

to serve as containers for other file formats, so that a single physical file can contain not only the visual

representation but also other representations including the original authored version, richer semantic

formats, and others. This part of ISO 19005 does not address the long-term suitability of formats, that

may be embedded, other than those compliant with any part of this International Standard.

These goals are accomplished by identifying the set of PDF components that can be used, and restrictions

on the form of their use, within conforming PDF/A files.

By itself, PDF/A does not necessarily ensure that the visual appearance of the content accurately

reflects any original source material used to create the conforming file, e.g. the process used to create

a conforming file might substitute fonts, reflow text, downsample images or use lossy compression.

Organizations that need to ensure that a conforming file is an accurate representation of original source

material might need to impose additional requirements on the processes that generate the conforming

file beyond those imposed by this part of ISO 19005, such as those best practices in Annex C. In addition,

it is important for those organizations to implement policies and practices regarding the inspection of

conforming files for correct visual appearance.

PDF/A does not directly address the topic of authenticity either for the underlying content to be visually

represented or the PDF/A file itself. Such authenticity is generally considered to be important for legal,

regulatory and governance purposes and is beyond the scope of this part of ISO 19005.

This part of ISO 19005 is one component of an organization’s electronic archival environment for long-

term retention of documents. Successful implementation of this part of ISO 19005 for archival purposes

depends upon:

— the retention requirements of an organization’s archival environment, records management policies

[6]
and procedures as specified in ISO 15489-1 ;

— any additional conditions necessary to ensure the persistence of electronic documents and their

[5] [7]

characteristics over time, including, but not limited to, those defined by ISO 14721 , ISO/TR 15801 ,

[8]
and ISO/TR 18492 ;
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ISO 19005-3:2012(E)

— quality assurance processes necessary to verify conformance with applicable requirements and

conditions, e.g. an inspection regime to verify the quality and integrity of converted source data.

This part of ISO 19005 is intended to lead to the development of various applications that read, render,

write and validate conforming files. Different applications will incorporate various capabilities to

prepare, interpret and process conforming files based on needs as perceived by the suppliers of those

applications. However, it is important to note that a conforming application needs to be able to read and

process appropriately all files complying with a specified conformance level.

This part of ISO 19005 extends the capabilities of ISO 19005-2. Just as with ISO 19005-2, it is based on

PDF version 1.7 (as defined in ISO 32000-1).

This part of ISO 19005 (in conjunction with its normative references) provides sufficient information to

interpret any conforming PDF/A-3 file.

NPES and AIIM (accredited standards developing organizations) maintain an ongoing series of

application notes for guiding developers and users of this part of ISO 19005. These application notes are

available at and

and-Publications/Standards/Articles/PDFA-Application-Notes>. Both NPES and AIIM will also retain

copies of the specific non-ISO normative references of this part of ISO 19005 which are publicly available

electronic documents.
vi © ISO 2012 – All rights reserved
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INTERNATIONAL STANDARD ISO 19005-3:2012(E)
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)
1 Scope

This part of ISO 19005 specifies the use of the Portable Document Format (PDF) 1.7, as formalized in

ISO 32000-1, for preserving the static visual representation of page-based electronic documents over

time in addition to allowing any type of other content to be included as an embedded file or attachment.

This part of ISO 19005 is not applicable to:

— specific processes for converting paper or electronic documents to the PDF/A format;

— specific technical design, user interface, implementation, or operational details of rendering;

— specific physical methods of storing these documents such as media and storage conditions;

— required computer hardware and/or operating systems.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

ISO/IEC 646, Information technology — ISO 7-bit coded character set for information interchange

ISO/IEC 10646, Information technology — Universal Coded Character Set (UCS)

ISO 15076-1, Image technology colour management — Architecture, profile format and data structure —

Part 1: Based on ICC.1:2010

ISO 15930-7:2010, Graphic technology — Prepress digital data exchange using PDF — Part 7: Complete

exchange of printing data (PDF/X-4) and partial exchange of printing data with external profile reference

(PDF/X-4p) using PDF 1.6

ISO 19005-1, Document management — Electronic document file format for long-term preservation —

Part 1: Use of PDF 1.4 (PDF/A-1)

ISO 19005-2, Document management — Electronic document file format for long-term preservation — Part

2:Use of ISO 32000-1 (PDF/A-2)
ISO 32000-1, Document management — Portable document format — Part 1: PDF 1.7

Extensible Markup Language (XML) 1.0 (Third Edition), W3C Recommendation, 4 February 2004. Available

at

1) The character encoding defined in ISO/IEC 646 is equivalent to ANSI X3.4 (ASCII) and ECMA-6.

2) The character code values defined in ISO/IEC 10646 are equivalent to those of Unicode.

© ISO 2012 – All rights reserved 1
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ISO 19005-3:2012(E)

ICC.1:1998-09, File Format for Color Profiles, International Color Consortium. Available at color.org/ICC-1_1998-09.PDF>

ICC.1:2001-12, File Format for Color Profiles (Version 4.0.0), International Color Consortium. Available at


ICC.1:2003-09, File Format for Color Profiles, International Color Consortium. Available at www.color.org/

ICC.1:2004-10, File Format for Color Profiles, International Color Consortium. Available at color.org/ICC-1_2004-10.PDF>

RDF/XML Syntax Specification (Revised), W3C Recommendation, 10 February 2004. Available at www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/>

XMP: Extensible Metadata Platform, (September 2005), Adobe Systems Incorporated. Available at www.aiim.org/documents/standards/xmpspecification.pdf>

Adobe Glyph List, 20 September 2002, Adobe Systems Incorporated. Available at com/public/developer/en/opentype/glyphlist.txt>

Adobe Supplement to ISO 32000-1, BaseVersion 1.7, ExtensionLevel 5, Adobe Systems Incorporated. Available

at
RFC 2315, PKCS #7: Cryptographic Message Syntax Version 1.5

RFC 3280, Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
conformance level

identified set of restrictions and requirements to which files and readers are required to comply

3.2
electronic document

electronic representation of a page-oriented aggregation of text, images and graphic data and metadata

useful to identify and understand that data, that can be reproduced on paper or other substrates, as well

as rendered electronically on display devices, without significant loss of its information content

3.3
end-of-file marker
five character sequence %%EOF marking the end of a PDF file
3.4
EOL marker
end-of-line marker

one or two character sequence marking the end of a line, consisting of a CARRIAGE RETURN character

(0Dh) or a LINE FEED character (0Ah) or a CARRIAGE RETURN followed immediately by a LINE FEED

3.5
extension schema

conforming XMP schema that is not defined in the XMP Specification nor ISO 19005-1 or ISO 19005-2

3.6
font
identified collection of graphics that may be glyphs or other graphic elements
[ISO 32000-1]
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ISO 19005-3:2012(E)
3.7
font program

software program written in a special-purpose language, such as the Type 1, TrueType, or OpenType font

format, that is understood by a specialized font interpreter
NOTE See ISO 32000-1:2008, 9.2.1.
3.8
interactive reader

reader that requires or allows human interaction with the content and other objects contained in the

document during the software’s processing phase

NOTE A file viewing tool is an example of an interactive reader; a raster image processor is an example of a

reader that is not interactive.
3.9
Level A conformance
conformance level encompassing all requirements of this part of ISO 19005
3.10
Level B conformance

conformance level encompassing the requirements of this part of ISO 19005 regarding the visual

appearance of electronic documents, but neither their structural or semantic properties nor the

requirement that all text have Unicode equivalents
3.11
Level U conformance

conformance level encompassing the requirements of this part of ISO 19005 regarding the visual appearance

of electronic documents, with the requirement that all text in the document have Unicode equivalents

3.12
long-term

period of time long enough for there to be concern about the impacts of changing technologies, including

support for new media and data formats, and of a changing user community, on the information being

held in a repository, which may extend into the indefinite future
3.13
PDF
Portable Document Format
file format defined in ISO 32000-1
3.14
reader
software application that is able to read and process PDF/A files
3.15
writer
software application that is able to write PDF/A files
3.16
XMP packet

structured wrapper for serialized XMP metadata that can be embedded in PDF as well as other file formats

4 Notation

PDF operators, PDF keywords, the names of keys in PDF dictionaries and other predefined names are

written in bold sans serif font; operands of PDF operators or values of dictionary keys are written in

italic sans serif font. Some names can also be used as values, depending on the context, and so the styling

of the content will be context specific.
EXAMPLE 1 The Default value for the TR2 key.
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ISO 19005-3:2012(E)

Token characters used to delimit objects and describe the structure of PDF files, as defined in

ISO 32000-1:2008, 7.2.1, may be identified by their ISO/IEC 646 character name written in upper case in

bold sans serif font followed by a parenthetic two digit hexadecimal character value with the suffix “h”.

EXAMPLE 2 CARRIAGE RETURN (0Dh).

Text string characters, as defined by ISO 32000-1:2008, 7.9.2, may be identified by their ISO/IEC 10646

character name written in uppercase in bold sans serif font followed by a parenthetic four digit

hexadecimal character code value with the prefix “U+”.
EXAMPLE 3 EN SPACE (U+2002).

The following terms, referring to this specification or parts thereof, are recommended when the full ISO

name is not being used:
— “PDF/A” – a synonym for the ISO 19005 family of standards;
— “PDF/A-1” – a synonym for ISO 19005-1;
— “PDF/A-1a” – a synonym for ISO 19005-1, Level A conformance;
— “PDF/A-1b” – a synonym for ISO 19005-1, Level B conformance;
— “PDF/A-2” – a synonym for ISO 19005-2;
— “PDF/A-2a” – a synonym for ISO 19005-2, Level A conformance;
— “PDF/A-2b” – a synonym for ISO 19005-2, Level B conformance;
— “PDF/A-2u” – a synonym for ISO 19005-2, Level U conformance;
— “PDF/A-3” – a synonym for ISO 19005-3;
— “PDF/A-3a” – a synonym for ISO 19005-3, Level A conformance;
— “PDF/A-3b” – a synonym for ISO 19005-3, Level B conformance;
— “PDF/A-3u” – a synonym for ISO 19005-3, Level U conformance.
5 Conformance levels
5.1 General

This part of ISO 19005 defines a file format for representing electronic documents known as “PDF/A-3”.

Conforming PDF/A-3 files shall adhere to all requirements of ISO 32000-1 as modified by this part of

ISO 19005. A conforming file may include any valid ISO 32000-1 feature that is not explicitly forbidden

by this part of ISO 19005. Features described in PDF specifications prior to Version 1.7, which are not

explicitly described in ISO 32000-1, should not be used.

NOTE 1 A conforming file is not obligated to use any PDF feature other than those explicitly required by

ISO 32000-1 or this part of ISO 19005.

As described in 6.1.2, the version number of a file may be any value from 1.0 to 1.7, and the value shall

not be used in determining whether a file is in conformance with this part of ISO 19005.

NOTE 2 The proper mechanism by which a file can presumptively identify itself as being a PDF/A-3 file of a

given conformance level is described in 6.6.4.
5.2 Level A conformance

Level A conforming files shall adhere to all of the requirements of this part of ISO 19005. A file meeting

this conformance level is said to be a “conforming PDF/A-3a file.”
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ISO 19005-3:2012(E)
5.3 Level B conformance

In recognition of the varying preservation needs of the diverse user communities making use of PDF

files, this part of ISO 19005 defines a Level B conformance level. Level B conforming files shall adhere

to all of the requirements of this part of ISO 19005 except those of 6.2.11.7 and 6.7. A file meeting this

conformance level is said to be a “conforming PDF/A-3b file.”

NOTE 1 The Level B conformance requirements are intended to be those minimally necessary to ensure

that the rendered visual appearance of a conforming file is preservable over the long term. However, Level B

conforming files might not have sufficiently rich internal information to allow for the preservation of the

document’s logical structure and content text stream in natural reading order, which is provided by Level A

conformance. The requirements for Level A conformance place greater responsibilities on writers of conforming

files and those preparing such files, but these requirements allow for a higher level of document preservation

service and confidence over time. Additionally, Level A conformance facilitates the accessibility of conforming

files for physically impaired users.

NOTE 2 A Level B conforming file can include features from Clauses 6.2.11.7 and 6.7, but still choose to identify

itself as Level B.
5.4 Level U conformance

In recognition of the varying preservation needs of the diverse user communities making use of PDF

files, this part of ISO 19005 defines a Level U conformance level. Level U conforming files shall adhere

to all of the requirements of this part of ISO 19005 except those of 6.7. A file meeting this conformance

level is said to be a “conforming PDF/A-3u file.”

NOTE 1 The Level U conformance requirements are intended to be those necessary to ensure that not only is

the rendered visual appearance of a conforming file preservable over the long term, but that any text contained in

the document can be reliably extracted as a series of Unicode codepoints. However, Level U conforming files might

not have sufficiently rich internal information to allow for the preservation of the document’s logical structure

and content text stream in natural reading order, which is provided by Level A conformance. The requirements

for Level A conformance place greater responsibilities on writers of conforming files and those preparing such

files, but these requirements allow for a higher level of document preservation service and confidence over time.

Additionally, Level A conformance facilitates the accessibility of conforming files for physically impaired users.

NOTE 2 A Level U conforming file can include features from Clause 6.7, but still choose to identify itself as Level U.

NOTE 3 Level U was introduced in ISO 19005-2 and therefore does not have an equivalent in ISO 19005-1.

5.5 Conforming readers

A conforming reader shall comply with all requirements regarding reader functional behaviour specified

in this part of ISO 19005. The requirements of this part of ISO 19005 with respect to reader behaviour

are stated in terms of general functional requirements applicable to all conforming readers. This part of

ISO 19005 does not prescribe any specific technical design, user interface or implementation details of

conforming readers.

The rendering and other processing of conforming files shall be performed as defined in ISO 32000-1

subject to the additional restrictions specified by this part of ISO 19005. Features described in PDF

specifications that are not explicitly described in ISO 32000-1 shall be ignored by conforming readers.

Conforming PDF/A-3 readers shall read and process appropriately all PDF/A-3 files. In addition,

conforming PDF/A-3 readers shall read and process appropriately all PDF/A-1 files as defined by

ISO 19005-1 and PDF/A-2 files as defined by ISO 19005-2.
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ISO 19005-3:2012(E)
6 Technical requirements
6.1 File structure
6.1.1 General

Subclauses 6.1.2 to 6.1.12 address overall file format issues and the base elements that form the general

structure of a conforming file.

Any data contained in a conforming file that is not described in ISO 32000-1 or this part of ISO 19005

should be ignored by a conforming reader and shall not be used to render content on a page.

6.1.2 File header

The file header shall begin at byte zero and shall consist of “%PDF-1.n” followed

...

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