ISO/IEC TS 30135-4:2014

TECHNICAL ISO/IEC
SPECIFICATION TS
30135-4
First edition
2014-11-15
Information technology — Digital
publishing — EPUB3 —
Part 4:
Open Container Format
Technologies de l'information — Publications numériques — EPUB3 —
Partie 4: Format de conteneur ouvert

Reference number
©
ISO/IEC 2014
©  ISO/IEC 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any
means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission.
Permission can be requested from either ISO at the address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO/IEC 2014 – All rights reserved

Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, the joint
technical committee may decide to publish an ISO/IEC Technical Specification (ISO/IEC TS), which
represents an agreement between the members of the joint technical committee and is accepted for
publication if it is approved by 2/3 of the members of the committee casting a vote.
An ISO/IEC TS is reviewed after three years in order to decide whether it will be confirmed for a further three
years, revised to become an International Standard, or withdrawn. If the ISO/IEC TS is confirmed, it is
reviewed again after a further three years, at which time it must either be transformed into an International
Standard or be withdrawn.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC TS 30135 series were prepared by Korean Agency for Technology and Standards (as KS X 6070
series) with International Digital Publishing Forum and were adopted, under a special “fast-track procedure”,
by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by the
national bodies of ISO and IEC.
ISO/IEC TS 30135 consists of the following parts, under the general title Information technology — Document
description and processing languages — EPUB 3:
—  Part 1: Overview
—  Part 2: Publications
—  Part 3: Content Documents
—  Part 4: Open Container Format
—  Part 5: Media Overlay
—  Part 6: Canonical Fragment Identifier
—  Part 7: Fixed-Layout Documents

EPUB Open Container Format (OCF) 3.0
Recommended Specification 11 October 2011
THIS VERSION
http://www.idpf.org/epub/30/spec/epub30-ocf-20111011.html
LATEST VERSION
http://www.idpf.org/epub/30/spec/epub30-ocf.html
PREVIOUS VERSION
http://www.idpf.org/epub/30/spec/epub30-ocf-20110908.html
A diff of changes from the previous draft is available at this link.
Please refer to the errata for this document, which may include some normative corrections.
All rights reserved. This work is protected under Title 17 of the United States Code. Reproduction and
dissemination of this work with changes is prohibited except with the written permission of the International
Digital Publishing Forum (IDPF).
EPUB is a registered trademark of the International Digital Publishing Forum.
Editors
James Pritchett, Learning Ally (formerly Recording for the Blind & Dyslexic)
Markus Gylling, DAISY Consortium
TAB LE O F CO NTENTS
1. Overview
1.1. Purpose and Scope
1.2. Terminology
1.3. Conformance Statements
1.4. Content Conformance
1.5. Reading System Conformance
2. OCF Abstract Container
2.1. Overview
2.2. File and Directory Structure
2.3. Relative IRIs for Referencing Other Components
2.4. File Names
2.5. META-INF
2.5.1. Container – META-INF/container.xml
2.5.2. Encryption – META-INF/encryption.xml
2.5.3. Manifest – META-INF/manifest.xml
2.5.4. Metadata – META-INF/metadata.xml
2.5.5. Rights Management – META-INF/rights.xml
2.5.6. Digital Signatures – META-INF/signatures.xml
3. OCF ZIP Container
3.1. Overview
3.2. ZIP File Requirements
3.3. OCF ZIP Container Media Type Identification
4. Font Obfuscation
4.1. Introduction
4.2. Obfuscation Algorithm
4.3. Generating the Obfuscation Key
4.4. Specifying Obfuscated Resources
A. Schemas
A.1. Schema for container.xml
A.2. Schema for encryption.xml
A.3. Schema for signatures.xml
B. Example
C. The application/epub+zip Media Type
D. Acknowledgements and Contributors
References
› 1 Overview
› 1.1 Purpose and Scope
This section is informative
This specification, EPUB Open Container Format (OCF) 3.0, defines a file format and processing model
for encapsulating the sets of related resources that comprise one or more EPUB® Publications into a
single-file container.
This specification is one of a family of related specifications that compose EPUB 3, the third major
revision of an interchange and delivery format for digital publications based on XML and Web Standards. It
is meant to be read and understood in concert with the other specifications that make up EPUB 3:
The EPUB 3 Overview [EPUB3Overview], which provides an informative overview of EPUB and a
roadmap to the rest of the EPUB 3 documents. The Overview should be read first.
EPUB Publications 3.0 [Publications30], which defines publication-level semantics and
overarching conformance requirements for EPUB Publications.
EPUB Content Documents 3.0 [ContentDocs30], which defines profiles of XHTML, SVG and CSS
for use in the context of EPUB Publications.
EPUB Media Overlays 3.0 [MediaOverlays30], which defines a format and a processing model for
synchronization of text and audio.
OCF is the required container technology for EPUB Publications. OCF may play a role in the following
workflows:
During the preparation steps in producing an electronic Publication, OCF may be used as the
container format when exchanging in-progress Publications between different individuals and/or
different organizations.
When providing an electronic Publication from publisher or conversion house to the distribution or
sales channel, OCF is the recommended container format to be used as the transport format.
When delivering the final Publication to an EPUB Reading System or User, OCF is the required
format for the container that holds all of the assets that make up the Publication.
The OCF specification defines the rules for structuring the file collection in the abstract: the "abstract
container". It also defines the rules for the representation of this abstract container within a ZIP archive:
the "physical container". The rules for ZIP physical containers build upon the ZIP technologies used by
[ODF]. OCF also defines a standard method for obfuscating embedded fonts for those EPUB
Publications that require this functionality.

This specification supersedes Open Container Format (OCF) 2.0.1 [OCF2]. Refer to [EPUB3Changes] for
information on differences between this specification and its predecessor.
› 1.2 Terminology
EPUB Publication (or Publication)
A logical document entity consisting of a set of interrelated resources and packaged in an
EPUB Container, as defined by this specification and its sibling specifications.
Publication Resource
A resource that contains content or instructions that contribute to the logic and rendering of
the EPUB Publication. In the absence of this resource, the Publication might not render as
intended by the Author. Examples of Publication Resources include the Package Document,
EPUB Content Documents, EPUB Style Sheets, audio, video, images, embedded fonts and
scripts.
With the exception of the Package Document itself, Publication Resources must be listed in
the manifest [Publications30] and must be bundled in the EPUB container file unless
specified otherwise in Publication Resource Locations [Publications30].
Examples of resources that are not Publication Resources include those identified by the
Package Document link [Publications30] element and those identified in outbound hyperlinks
that resolve outside the EPUB Container (e.g., referenced from an [HTML5] a element href
attribute).
EPUB Content Document
A Publication Resource that conforms to one of the EPUB Content Document definitions
(XHTML or SVG).
An EPUB Content Document is a Core Media Type, and may therefore be included in the
EPUB Publication without the provision of fallbacks [Publications30].
XHTML Content Document
An EPUB Content Document conforming to the profile of [HTML5] defined in XHTML Content
Documents [ContentDocs30].
XHTML Content Documents use the XHTML syntax of [HTML5].
SVG Content Document
An EPUB Content Document conforming to the constraints expressed in SVG Content
Documents [ContentDocs30].
Core Media Type
A set of Publication Resource types for which no fallback is required. Refer to Publication
Resources [Publications30] for more information.
Package Document
A Publication Resource carrying bibliographical and structural metadata about the EPUB
Publication, as defined in Package Documents [Publications30].
Manifestation
The digital (or physical) embodiment of a work of intellectual content. Changes to the content
such as significant revision, abridgement, translation, or the realization of the content in a
different digital or physical form result in a new manifestation. There may be many individual

but identical copies of a manifestation, termed 'instances' or 'items'. The ISBN is an example
of a manifestation identifier, and is shared by all instances of that manifestation.
All instances of a manifestation need not be bit-for-bit identical, as minor corrections or
revisions are not judged to create a new manifestation or work.
Unique Identifier
The Unique Identifier is the primary identifier for an EPUB Publication, as identified by the
unique-identifier attribute. The Unique Identifier may be shared by one or many
Manifestations of the same work that conform to the EPUB standard and embody the same
content, where the differences between the Manifestations are limited to those changes that
take account of differences between EPUB Reading Systems (and which themselves may
require changes in the ISBN).
The Unique Identifier is less granular than the ISBN. However, significant revision,
abridgement, etc. of the content requires a new Unique Identifier.
EPUB Style Sheet (or Style Sheet)
A CSS Style Sheet conforming to the CSS profile defined in EPUB Style Sheets
[ContentDocs30].
Viewport
The region of an EPUB Reading System in which the content of an EPUB Publication is
rendered visually to a User.
EPUB Container (or Container)
The ZIP-based packaging and distribution format for EPUB Publications defined in OCF ZIP
Container.
OCF Processor
A software application that processes EPUB Containers according to this specification.
Author
The person(s) or organization responsible for the creation of an EPUB Publication, which is
not necessarily the creator of the content and resources it contains.
User
An individual that consumes an EPUB Publication using an EPUB Reading System.
EPUB Reading System (or Reading System)
A system that processes EPUB Publications for presentation to a User in a manner
conformant with this specification and its sibling specifications.
› 1.3 Conformance Statements
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD
NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described
in [RFC2119].
All sections of this specification are normative except where identified by the informative status label
"This section is informative". The application of informative status to sections and appendices applies to
all child content and subsections they may contain.
All examples in this specification are informative.

1.4 Content Conformance
›
› An OCF Abstract Container must meet the conformance constraints defined in OCF Abstract
Container.
› An OCF ZIP Container (also referred to as an EPUB Container) must meet the conformance
constraints defined in OCF ZIP Container.
› 1.5 Reading System Conformance
An EPUB Reading System must meet all of the following criteria:
› It must process the OCF ZIP Container in conformance with all Reading System conformance
constraints expressed in OCF ZIP Container.
› If it has a Viewport, it must support deobfuscation of fonts as defined in Font Obfuscation.
› 2 OCF Abstract Container
› 2.1 Overview
This section is informative
An OCF Abstract Container defines a file system model for the contents of the container. The file system
model uses a single common root directory for all of the contents of the container. All (non-remote)
resources for embedded Publications are located within the directory tree headed by the container’s root
directory, although no specific file system structure is mandated for this. The file system model also
includes a mandatory directory named META-INF that is a direct child of the container's root directory and
is used to store the following special files:
container.xml [required]
Identifies the file that is the point of entry for each embedded Publication.
signatures.xml [optional]
Contains digital signatures for various assets.
encryption.xml [op
...