ISO 19005-4:2020

INTERNATIONAL ISO
STANDARD 19005-4
First edition
2020-11
Document management — Electronic
document file format for long-term
preservation —
Part 4:
Use of ISO 32000-2 (PDF/A-4)
Reference number
ISO 19005-4:2020(E)
©
ISO 2020

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ISO 19005-4:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Email: copyright@iso.org
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Published in Switzerland
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ISO 19005-4:2020(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Notation . 2
5 Conformance . 3
5.1 Conforming Files . 3
5.2 Conforming Processor . 4
6 Technical requirements . 4
6.1 File structure . 4
6.1.1 General. 4
6.1.2 File header . 4
6.1.3 File trailer . . . 4
6.1.4 Cross reference table . 4
6.1.5 String objects . 5
6.1.6 Stream objects . 5
6.1.7 Name objects . 5
6.1.8 Indirect objects . 5
6.1.9 Inline image dictionaries . 5
6.1.10 Linearized PDF . 6
6.1.11 Permissions . 6
6.1.12 Document catalog dictionary . 6
6.2 Graphics . 6
6.2.1 General. 6
6.2.2 Content streams. 6
6.2.3 Output intent . 7
6.2.4 Colour spaces . 7
6.2.5 Extended graphics state. 9
6.2.6 Flatness .10
6.2.7 Images .10
6.2.8 XObjects .11
6.2.9 Transparency .11
6.2.10 Fonts .11
6.3 Annotations.15
6.3.1 Annotation types .15
6.3.2 Annotation dictionaries .15
6.3.3 Annotation appearances .15
6.3.4 Display of annotation contents .16
6.4 Interactive forms .16
6.4.1 General.16
6.4.2 XFA forms .16
6.5 Digital signatures .16
6.5.1 General.16
6.5.2 Signature profiles .17
6.5.3 Proof of existence .17
6.5.4 Validation .17
6.6 Action .18
6.6.1 General.18
6.6.2 Handling of JavaScript actions .18
6.6.3 Trigger events .18
6.6.4 Handling of GoToR, GoToE, URI and SubmitForm actions .19
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ISO 19005-4:2020(E)

6.7 Metadata .19
6.7.1 General.19
6.7.2 Metadata streams .19
6.7.3 Version identification . .20
6.7.4 File identifiers .20
6.7.5 File provenance information .21
6.8 Logical structure .21
6.9 Embedded files .21
6.10 Optional content .22
6.11 Use of alternate presentations and transitions .23
6.12 Document requirements .23
6.13 Print scaling .23
6.14 Geospatial .23
6.15 Measurement Properties .23
Annex A (normative) Requirements for a PDF/A with Embedded Files (PDF/A-4f) .24
Annex B (normative) Requirements for a PDF/A for Engineering (PDF/A-4e) .25
Bibliography .27
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ISO 19005-4:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 171, Document management applications,
SC 2, Document file formats, EDMS systems and authenticity of information.
A list of all parts in the ISO 19005 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 19005-4:2020(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 document is part of a series of documents, of which this is part 4. 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 visual
appearance over time, independent of the tools and systems used for creating, storing or rendering the
files. Some parts of ISO 19005 also define a framework for representing the logical structure and other
semantic information of electronic documents within conforming files. 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.
Parts 3 & 4 in this series 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 standard does not
address the long-term suitability of formats, that may be embedded, other than those compliant with
any part of this document.
1)
This document is based on PDF version 2.0 (as defined in ISO 32000-2:— ) and as such provides
recommendations in how to properly archive content that uses some of the newer features present
there including page level output intents, associated files and improvements to tagged PDF.
This document also introduces some new directions in archiving non-static content that can be present
in PDF documents, such as form fields and ECMAScript. It seeks to preserve more information in the
file (by not requiring its removal during the archival process) and puts a greater burden on conforming
viewers to ensure that such information does not alter the visual appearance of the file during
consumption.
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 document. In addition, it is important for those organizations to
implement policies and practices regarding the inspection of conforming files for correct visual
appearance.
This document is one component of an organization's electronic archival environment for long-term
retention of documents. Successful implementation of this document for archival purposes depends upon:
— the retention requirements of an organization's archival environment, records management policies
[2]
and procedures as specified in ISO 15489-1 ;
1) Under preparation. Stage at the time of publication: ISO/FDIS 32000-2.
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ISO 19005-4:2020(E)

— any additional conditions necessary to ensure the persistence of electronic documents and
[1]
their characteristics over time, including, but not limited to, those defined by ISO 14721 , and
[3]
ISO/TR 18492 ;
— 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 document 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 document (in conjunction with its normative references) provides sufficient information to
interpret any conforming PDF/A-4 file.
The PDF Association may maintain an ongoing series of application notes for guiding developers and
users of this document. These application notes are available at https:// www .pdfa .org/ . The PDF
Association will also retain copies of the specific non-ISO normative references of this document which
are publicly available electronic documents.
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INTERNATIONAL STANDARD ISO 19005-4:2020(E)
Document management — Electronic document file format
for long-term preservation —
Part 4:
Use of ISO 32000-2 (PDF/A-4)
1 Scope
This document specifies the use of the Portable Document Format (PDF) 2.0, as formalized in
ISO 32000-2:—, 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 document does not apply 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 documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 14533-3, Processes, data elements and documents in commerce, industry and administration — Long term
signature profiles — Part 3: Long term signature profiles for PDF Advanced Electronic Signatures (PAdES)
ISO 16684-2, Graphic technology — Extensible metadata platform (XMP) — Part 2: Description of XMP
schemas using RELAX NG
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 32000-2:—, Document management — Portable document format — Part 2: PDF 2.0
XMP Specification Part 2: Additional Properties – Adobe Systems – https:// www .adobe .com/ content/
dam/ acom/ en/ devnet/ xmp/ pdfs/ XMPSDKReleasecc -2020/ XMPSpecificationPart2 .pdf
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
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ISO 19005-4:2020(E)

3.1
end-of-file marker
five-character sequence %%EOF marking the end of a PDF file
3.2
extension schema
conforming XMP schema that is not defined in the XMP Specification nor part 1 or part 2 of this
document
3.3
font
identified collection of graphics that may be glyphs or other graphic elements
[SOURCE: ISO 32000-2:—]
3.4
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 (3.3) interpreter
[SOURCE: ISO 32000-2:—]
3.5
interactive processor
processor (3.8) that requires or allows human interaction with the content and other objects contained
in the document during the software's processing phase
Note 1 to entry: A file viewing tool is an example of an interactive processor; a raster image processor is an
example of a processor that is not interactive.
3.6
long-term
period of time long enough for there to be concern about the impacts of changing technologies
3.7
PDF
Portable Document Format
file format defined in ISO 32000-2:—
3.8
processor
software application that is able to read and process conforming files
3.9
writer
software application that is able to write conforming files
3.10
XMP packet
structured wrapper for serialized XMP metadata
[SOURCE: ISO 32000-2:—]
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 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 19005-4:2020(E)

Token characters used to delimit objects and describe the structure of PDF files, as defined in
ISO 32000-2: —, 7.2.1, may be identified by their ISO/IEC 646 character name written in upper case in
bold 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 32000-2:—, 7.9.2, may be identified by their ISO/IEC 10646
character name written in uppercase in bold 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-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;
— “PDF/A-4” – a synonym for ISO 19005-4;
— “PDF/A-4e” – a synonym for ISO 19005-4 Level E conformance;
— “PDF/A-4f” – a synonym for ISO 19005-4 Level F conformance;
5 Conformance
5.1 Conforming Files
This document defines a file format for representing electronic documents known as “PDF/A-4”.
Conforming PDF/A-4 files shall adhere to all requirements of ISO 32000-2:— as modified by this document.
A conforming file may include any valid ISO 32000-2:— feature that is not explicitly forbidden by this
document. Features described in specifications which are not explicitly described in ISO 32000-2:—,
should not be used. Features described as deprecated in ISO 32000-2:— shall not be used.
NOTE A conforming file is not obligated to use any PDF feature other than those explicitly required by
ISO 32000-2:— or this document.
The proper mechanism by which a file can presumptively identify itself as being a conforming PDF/A-4
file is described in 6.7.3.
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ISO 19005-4:2020(E)

5.2 Conforming Processor
A conforming processor shall comply with all requirements regarding processor functional behaviour
specified in this document. The requirements of this document with respect to processor behaviour
are stated in terms of general functional requirements applicable to all conforming processors. This
document does not prescribe any specific technical design, user interface or implementat
...