Please check the errata for any errors or issues reported since publication.
Copyright © 2019-2020 W3C® (MIT, ERCIM, Keio, Beihang). W3C liability, trademark and permissive document license rules apply.
This specification describes the requirements for the creation of audiobooks, using a profile of the Publication Manifest specification.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.
This document was published by the Publishing Working Group as a Candidate Recommendation. This document is intended to become a W3C Recommendation.
GitHub Issues are preferred for discussion of this specification. Alternatively, you can send comments to our mailing list. Please send them to public-publ-wg@w3.org (archives).
W3C publishes a Candidate Recommendation to indicate that the document is believed to be stable and to encourage implementation by the developer community. This Candidate Recommendation is expected to advance to Proposed Recommendation no earlier than 31 March 2020.
Please see the Working Group's implementation report.
Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
This document is governed by the 1 March 2019 W3C Process Document.
This section is non-normative.
An Audiobook is a collection of audio resources grouped together by a reading order, metadata, and resources, all contained in a manifest. This Audiobook can live on the Open Web Platform, or as a packaged entity.
This specification is intended to standardize the audiobooks distribution model on the web and between businesses. It should facilitate different user agent architectures for the consumption of Audiobooks. The primary goal is to bring clarity to a part of the publishing industry currently underserved by standards, while opening Audiobooks to the Open Web Platform and new user agents. This specification does not outline what file types or formats should be used by content creators, only a manifest format for delivering them.
This specification does not define how user agents are expected to render Audiobooks. Details about the types of affordances that user agents can provide to enhance the reading experience for users are instead defined in [pwp-ucr].
Terms with meanings specific to the publishing industry are capitalized in this document (e.g., "Reading System"). A complete list of these terms and definitions is provided in [pub-manifest].
Only the first instance of a term in a section is linked to its definition.
In addition, the following terminology is defined for use in this specification:
Supplemental content is any content relating to the audiobook content but not required for the full experience of the publication. Examples of supplemental content include photographs, charts, or data relating to topics mentioned in the audiobook.
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MAY, MUST, MUST NOT, RECOMMENDED, REQUIRED, and SHOULD in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
The primary entry page is an HTML resource that represents the preferred starting resource of an Audiobook and enables discovery of its manifest. It typically introduces the audiobook and provides access to the content.
The primary entry page MUST include either a link to the manifest or embed the manifest [pub-manifest]. It also SHOULD contain the table of contents.
An Audiobook MUST include a primary entry page except when packaging allows alternative discovery of the manifest. When present, the page MUST be included in the resource list.
The table of contents provides a hierarchical list of links that reflects the structural outline of the major sections of the Audiobook and any supplemental content it may contain.
The table of contents is expressed via an [html] element (typically a nav element) in
one of the resources. This element MUST be identified by the
role attribute [html] value "doc-toc"
[dpub-aria-1.0].
If the table of contents is located in the primary entry page, the table of contents MUST be the first element in the document — in document tree order [dom] — with that role value. Otherwise, the manifest SHOULD identify the resource that contains the structure.
If the table of contents is not located in the primary entry page, the manifest SHOULD identify the resource that contains the structure.
When an Audiobook contains additional resources (i.e. supplemental content):
a table of contents SHOULD be included;
the table of contents SHOULD include a link to any of the resources; and
and all links SHOULD refer to publication resources [pub-manifest].
When including supplemental content, be aware that users might not have access to this content unless it is linked to from the table of contents. It is strongly advised to provide links to all content that is not in the default reading order.
This section is non-normative.
The Audiobook manifest is defined by a set of properties that describe the basic information a user agent requires to process and render an Audiobook. These properties are categorized in the Publication Manifest [pub-manifest]. Where these properties are extended from the Publication Manifest is specified in this section.
The Audiobook manifest is defined as a specific "shape" of [json-ld11]. This shape is also defined, informally, through a JSON schema [json-schema] that expresses the constraints defined in this specification. This schema is maintained at https://www.w3.org/ns/pub-schema/audiobooks/.
The requirements for the expression of Audiobook properties and resource relations are defined as follows:
The list of properties uses the formal names for each property as described in [schema.org] and [pub-manifest]. A descriptive label is included in parentheses where the purpose of these properties might be unclear.
conformsTo
@context
readingOrder
name
(publication title) abridged
accessibilityFeature
accessibilityHazard
accessibilitySummary
accessMode
accessModeSufficient
author
cover
duration
dateModified
datePublished
id
(canonical identifier) inLanguage
(publication language) readBy
readingProgression
resources
type
url
(address)
Some properties are implicitly required, as they are compiled from alternative
information when not explicitly authored. Refer to the internal
representation data models [pub-manifest] for more
information (the Audiobooks representation only differs in the default value for the
type
term).
An Audiobook manifest has to start by setting the JSON-LD context [json-ld]. The context has the following two major components:
https://schema.org
https://www.w3.org/ns/pub-context
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
…
}
To add the global language and direction of the manifest metadata, language and direction declaration [pub-manifest] can also be added to the context:
{
"@context" : [
"https://schema.org",
"https://www.w3.org/ns/pub-context",
{"language":"fr"}
]
...
}
The conformance URL expressed in the conformsTo
term [pub-manifest] MUST be "https://www.w3.org/TR/audiobooks/
".
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/"
…
}
The Publication Type is defined using the
type
term [pub-manifest].
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"type" : "Audiobook"
…
}
If a type
is not specified, Audiobook
[schema.org] is assumed as the
default.
A creator is an individual or entity responsible for the creation of the Audiobook. The Audiobooks profile can use the full list of creators defined in [pub-manifest].
The creators list includes two recommended creators for Audiobooks:
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
"type" : "Audiobook",
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type" : "Person",
"name" : "Charlotte Bronte"
}
}
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/";
"@context": ["https://schema.org", "https://www.w3.org/ns/pub-context"],
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type": "Person",
"name": "Charlotte Bronte"
}
"readBy" : {
"type": "Person",
"name": "Ivan Herman",
"id" : "https://www.w3.org/People/Ivan/"
}
}
A duration is the length of the audio resources in an Audiobook. The duration property is fully defined in Publication Manifest [pub-manifest].
Duration SHOULD be expressed for the entirety of the audiobook as part of the manifest, and SHOULD be present at the item level in the default reading order.
When a content creator specifies both the duration for the audiobook and item-level duration in the default reading order the resource-level duration SHOULD be equal to the sum of the durations of the items in the reading order.
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type" : "Person",
"name" : "Charlotte Bronte"
},
"duration" : "PT12345.235S"
}
The default reading order [pub-manifest] is a specific progression through the audio resources in the audiobook.
The default reading order MUST contain at least one audio
resource, which MAY be identified by the type
of
LinkedResource
[pub-manifest]. The default
reading order MUST NOT contain non-audio resources.
An audio resource can be referenced in its entirety via a URL [url], or for content where multiple chapters occupy a single file by using media fragments [media-frags] to locate the exact starting and end points.
It is important to note that a resource cannot be referenced more than once in the reading order. In the case where an audio file represents the content of multiple chapters or sections of the book, the table of contents can be used to specify the starting and ending points of those chapters in the larger audio file, as demonstrated in this example.
Annotations can also use media fragments to identify the location of the annotation in the resource, and are compatible with the Web Annotations model. This method will only apply to audiobook manifests that are not packaged.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : [{
"type" : "LinkedResource",
"url" : "audio/janeeyre.mp3",
"encodingFormat" : "audio/mp3",
"name" : "Jane Eyre",
"duration" : "PT124503.123S"
}]
}
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : [{
"type": "LinkedResource",
"url" : "audio/part001.wav#t=0,457.931",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 1",
"duration" : "PT457.931S"
}, {
"type" : "LinkedResource",
"url" : "audio/part002.wav#t=12.741",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 2",
"duration" : "PT234.245S"
}]
}
The resource list enumerates any additional
resources used in the processing and rendering of an audiobook that are not listed in the reading
order. It is expressed using the resources
property.
If an audiobook includes supplemental content it MUST be referenced in the resource list.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [
"cover.jpg",
"portrait_CB.jpg",
"supplement.pdf"
]
}
Previews are a common way to provide users an experience of the full content before purchasing or downloading the full audiobook.
A preview is identified using the
preview
link relation, as defined in [pub-manifest].
Previews MAY be located externally or included as a resource of the audiobook.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [{
"type" : "LinkedResource",
"url" : "https://publisher.example.org/jane-eyre-preview.wav",
"encodingFormat" : "audio/wav",
"rel" : "preview"
}]
}
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [{
"type" : "LinkedResource",
"url" : "preview.wav",
"encodingFormat" : "audio/wav",
"rel" : "preview"
}]
}
This section is non-normative.
Audiobooks will be packaged using the method described in the Lightweight Packaging Format [lpf] note.
This section is non-normative.
The history of the audiobook is rooted in the world of accessibility. Both purely audio publications and publications that synchronize text and audio playback have long been used to assist users with alternative reading needs and preferences.
An approach for accessible synchronized media in publications is currently being done by the Synchronized Multimedia for Publications Community Group. Refer to the work of that group for more information about creating such content and incorporating it into an Audiobook.
Alternatively, a content creator can provide the text equivalent as HTML [html] resources in the resources.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : {
"type" : "LinkedResource",
"url" : "audio/part001.wav#t=0",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 1",
"duration" : "PT457.931S",
"alternate" : {
"type" : "LinkedResource"
"url" : "text/part001-1.html",
"encodingFormat" : "text/html"}
},
"resources" : [{
"type": "LinkedResource",
"url": "text/part001-1.html",
"encodingFormat" : "text/html"
}...
]
}
This section depends on the Infra Standard [infra].
The specification extends the Publication Manifest processing algorithms [pub-manifest] as follows:
The following extension steps are added for Audiobook manifests:
(§ 4.1 Primary Entry
Page and § 4.2
Table of Contents) If document is not defined or does not
include an [html] element with the role
doc-toc
:
let toc be a boolean value set to false
.
for each
resource of processed["resources"], if
resource["rel"] is defined and contains the value
contents
, set toc to true
, then break.
if toc is not true
, validation
error.
This step checks for a table of contents in the resource list when an Audiobook
manifest is not linked to a primary entry page (i.e., when document
is
not defined) or the entry page does not include a table of contents.
(§ 5.6.2 Duration) Check the duration of the publication as follows:
Let resourceDuration hold the total duration of individual resources.
For each resource of data["readingOrder"]:
if resource["duration"] is not defined, validation error.
otherwise, if resource["duration"], add resource["duration"] to resourceDuration.
If the values cannot be compared because data["duration"] is not set, validation error.
Otherwise, if resourceDuration does not specify the same total duration as data["duration"], validation error.
This steps checks both that all resource in the reading order specify a duration and that the sum of all those durations matches the total duration for the publication.
A validation error is only emitted while checking each resource if the resource does not specify a duration. The validity of the durations [pub-manifest] is already checked in the publication manifest algorithm so does not need to be repeated.
The following extension steps are added for Audiobook manifests:
(§ 5.7 Default Reading Order) Check the reading order as follows:
If data["readingOrder"] is not set, fatal error.
For each resource in data["readingOrder"], if resource is not an audio resource, validation error, remove resource from data["readingOrder"].
If data["readingOrder"] is an empty list, fatal error.
This step ensures that only audio resources are listed in the reading order and removes any that are not.
If the reading order does not contain any entries after checking each resource, a fatal error is returned as the publication is not a valid audiobook.
(§ 5.5 Publication
Type) If data["type"] is not set or is an empty list, validation
error, set to « "Audiobook" »
.
This step sets the default type of the publication to Audiobook
when a
type property has not been specified.
(§ 5.2 Requirements) Check that each of the following properties is set. If not, issue a validation error for each one.
This step checks that all the recommended properties have been set. For more information about these, refer to § 5.2 Requirements.
(§ 5.2
Requirements) If no resource in data["readingOrder"] or
data["resources"] has a rel
entry that contains the relation
cover
, validation
error.
This step checks the reading order and resource list to verify that a cover has been
specified (i.e., an resource has the value cover
in its
rel
property).
This section is non-normative.
This specification extends the Publication Manifest’s User Agent Processing Algorithm for Machine-Processable Table of Contents [pub-manifest] to locate a table of content element as follows:
See also § 4.2 Table of Contents for further details.
As Audiobooks is a profile of Publication Manifest [pub-manifest], all security and privacy considerations detailed in that specification are applicable to this profile.
This profile acknowledges the following considerations:
This section is non-normative.
This section outlines the expected user agent behaviors for implementation of audiobooks. For processing
instructions, user agents should refer to the Processing a
Manifest
section of the Publication Manifest [pub-manifest] specification, and conform to any behavior described there.
All user agent behaviors described in this section are intended to provide implementors with guidance, not strict requirements. Behaviors in this document are taken mainly from the Use Cases and Requirements [pwp-ucr] note published by the working group.
As outlined in the Use Cases and Requirements [pwp-ucr] note, an audiobook must be navigable in the User Agent. This means that a User Agent must provide methods for the user to move through the audiobook in a linear or non-linear fashion by either moving through the Reading Order seamlessly or by accessing the Table of Contents. The User Agent should also allow the user to move through individual audio files in short time increments.
For an audiobook, the User Agent should provide a player interface [pwp-ucr] that will allow the user to navigate, play, or pause the audiobook. This interface can be represented to the user in any way (i.e. physical buttons, visual interface, keyboard input, or voice commands), but should be accessible at any point in the listening experience.
The Use Cases and Requirements [pwp-ucr] note recommends that content be available offline and that any packaged formats should not affect the iterations of the publications. This means that even if the content is copied many times to many users via multiple User Agents, the core manifest and its identifier are never changed.
This specification recommends the Lightweight Packaging Format [lpf] for packaging audiobook content, but this is not a requirement. Audiobook User Agents should be able to ingest LPF files for play, and should display content according to the requirements and recommendations in this document.
If a User Agent is serving the content directly from their service (i.e. as a retailer or repository of content), it is recommended that they provide a method for offlining or downloading the content to the user. This can be in any format they choose, but the audiobook should be complete and valid and the contents listed in the manifest should be served in their entirety. Even if a User Agent does not support the display of a certain resource (i.e. an image file or data table), it should still be available to the user for download.
This specification does not provide a method for content creators to protect or watermark their content, as there are existing methods available in the market today. User Agents who work with content creators that wish to protect or limit the distribution of their content can choose a method that works best for their requirements.
This specification recommends and provides a method for content creators to create fully accessible audiobooks. User Agents should use this information,
in the section on Accessibility, to implement accessible audiobook interfaces. It is recommended
that User Agents provide accessible player interfaces, as well as a method for content creators who
have provided alternate
content to have that content displayed.
For a complete list of issues addressed, refer to the GitHub tracker.
This section is non-normative.
A manifest for an audiobook. The canonical version of this manifest is also available.
{
"@context": ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"type": "Audiobook",
"id": "https://librivox.org/flatland-a-romance-of-many-dimensions-by-edwin-abbott-abbott/",
"url": "https://w3c.github.io/wpub/experiments/audiobook/",
"name": "Flatland: A Romance of Many Dimensions",
"author": "Edwin Abbott Abbott",
"readBy": "Ruth Golding",
"publisher": "Librivox",
"inLanguage": "en",
"dateModified": "2018-06-14T19:32:18Z",
"datePublished": "2008-10-12",
"duration": "PT15153S",
"license": "https://creativecommons.org/publicdomain/zero/1.0/",
"resources": [
{
"rel": "cover",
"url": "http://ia800704.us.archive.org/9/items/LibrivoxCdCoverArt12/Flatland_1109.jpg",
"encodingFormat": "image/jpeg"
},{
"rel": "contents",
"url": "toc.html",
"encodingFormat": "text/html"
}
],
"readingOrder": [
{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_1_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1371,
"name": "Part 1, Sections 1 - 3"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_2_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1669,
"name": "Part 1, Sections 4 - 5"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_3_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1506,
"name": "Part 1, Sections 6 - 7"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_4_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1669,
"name": "Part 1, Sections 8 - 10"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_5_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1506,
"name": "Part 1, Sections 11 - 12"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_6_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1798,
"name": "Part 2, Sections 13 - 14"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_7_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1225,
"name": "Part 2, Sections 15 - 17"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_8_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1371,
"name": "Part 2, Sections 18 - 20"
},{
"url": "http://www.archive.org/download/flatland_rg_librivox/flatland_9_abbott.mp3",
"encodingFormat": "audio/mpeg",
"duration": 1659,
"name": "Part 2, Sections 21 - 22"
}
]
}
A manifest for an audiobook with supplemental content.
{
"@context" : ["https://schema.org", "https://www.w3/org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"id" : "https://publisher.example.com/janeeyre",
"url" : "https://publisher.example.com/janeeyre",
"name" : "Jane Eyre",
"author" : "Charlotte Bronte",
"readBy" : "Jane Doe",
"duration" : "PT123456.789S",
"abridged" : false,
"inLanguage" : "en",
"dateModified" : "2019-03-29T15:59:00Z",
"datePublished" : "2019-03-29",
"readingOrder": [
{"url": "audio/chapter001.aac", "encodingFormat": "audio/aac", "name": "Chapter 1", "duration": "PT1234.567S"},
{"url": "audio/chapter002.aac", "encodingFormat": "audio/aac", "name": "Chapter 2", "duration": "PT890.123S"},
{"url": "audio/chapter003.aac", "encodingFormat": "audio/aac", "name": "Chapter 3", "duration": "PT456.789S"},
{"url": "audio/chapter004.aac", "encodingFormat": "audio/aac", "name": "Chapter 4", "duration": "PT987.654S"},
{"url": "audio/chapter005.aac", "encodingFormat": "audio/aac", "name": "Chapter 5", "duration": "PT321.987S"}
],
"resources": [
{"rel": "cover", "url": "images/cover.jpg", "encordingFormat": "image/jpeg"},
{"rel": "contents", "url": "toc.html", "encodingFormat": "text/html"},
{"url": "haworth_house.pdf", "encodingFormat": "application/pdf"}
]
}
This section is non-normative.
A primary entry page with a simple table of contents for an audiobook.
<head>
…
<script type="application/ld+json">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
…
"url" : "https://publisher.example.org/janeeyre",
…
}
</script>
…
</head>
<body>
…
<section role="doc-toc">
<ol>
<li><a href="audio/chapter001.wav">Chapter 1. There was no possibility of taking a walk that day...</a></li>
<li><a href="audio/chapter002.wav">Chapter 2. I resisted all the way:...</a></li>
<li><a href="audio/chapter003.wav">Chapter 3. The next thing I remember is,...</a></li>
…
</ol>
</section>
…
</body>
A table of contents for a simple audiobook.
<nav role="doc-toc">
<h2>JANE EYRE</h2>
<ol>
<li><a href="audio/chapter001.mp3">Chapter 1. There was no possibility of taking a walk that day...</a></li>
<li><a href="audio/chapter002.mp3">Chapter 2. I resisted all the way:...</a></li>
<li><a href="audio/chapter003.mp3">Chapter 3. The next thing I remember is,...</a></li>
…
</ol>
</nav>
A table of contents using media fragment references to locations in a single audio track.
<nav role="doc-toc">
<h2>JANE EYRE</h2>
<ol>
<li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=0,456.788">Chapter 1</a></li>
<li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=456.789,1234.566">Chapter 2</a></li>
<li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=1234.567">Chapter 3</a></li>
</ol>
</nav>
This section is non-normative.
The editor would like to thank the members of the Publishing Working Group for their contributions to this specification:
The Working Group would also like to thank the members of the Digital Publishing Interest Group for all the hard work they did paving the road for this specification.