Summary

Include accessibility metadata in ONIX records so that it is available in distribution channels.

Examples

Example 1 — Sample ONIX message featuring accessibility information 
<ONIXMessage release="3.0">
  <Header>
    …
  </Header>
  <Product>
    …
    <DescriptiveDetail>
      <ProductFormFeature>
        <ProductFormFeatureType>09</ProductFormFeatureType>
        <ProductFormFeatureValue>03</ProductFormFeatureValue>
      </ProductFormFeature>
      <ProductFormFeature>
        <ProductFormFeatureType>09</ProductFormFeatureType>
        <ProductFormFeatureValue>10</ProductFormFeatureValue>
      </ProductFormFeature>
      <ProductFormFeature>
        <ProductFormFeatureType>09</ProductFormFeatureType>
        <ProductFormFeatureValue>11</ProductFormFeatureValue>
      </ProductFormFeature>
      <ProductFormFeature>
        <ProductFormFeatureType>09</ProductFormFeatureType>
        <ProductFormFeatureValue>13</ProductFormFeatureValue>
      </ProductFormFeature>
    </DescriptiveDetail>
    …
    <TitleDetail>
      <TitleType>01</TitleType>
      <TitleElement>
        <TitleElementLevel>01</TitleElementLevel>
        <TitleText>Accessible EPUB 3</TitleText>
      </TitleElement>
    </TitleDetail>
    …
  </Product>
</ONIXMessage>
Example 2 — Linking an ONIX message 
<package … >
    <metadata>
        …
        <link
              rel="onix-record"
              href="#EPUB/meta/onix-9781234567890.xml"/>
        …
    </metadata> 
    …
</package>

Frequently Asked Questions

Does the ONIX message have to be included in the EPUB container?

No, ONIX messages are not publication resources so can be hosted outside the container. When considering external hosting of resources, duly consider that not all user agents are connected to the internet; an accessible device may wind up without access to your accessibility information.

Can I use other metadata standards to include accessibility information?

Yes, schema.org includes a set of accessibility properties that enable accessibility metadata to be embedded directly in an EPUB package file.

How is this metadata useful?

The metadata can be used in distribution channels to allow users to discover whether the publication is suitable for their needs, as one example. A book store search engine could use the information to allow users to filter the available ebooks to only those that they know will work with their assistive technology.

The user agent could similarly present the accessibility information to the user in advance of reading even if the book has been delivered through a less accessible channel (e.g., enabling a quicker return of the ebook if it's known to be incompatible with their system).

Without this information, the user has no way to distinguish the quality of one EPUB from another.

Explanation

ONIX Code List 196 enables the inclusion accessibility compliance metadata in an ONIX message. This information can then travel with the publication through distribution channels so that customers can be made aware of the accessible features the EPUB offers. Each success criteria will be handled in turn in this section.

00: Accessibility Summary

<ProductFormFeatureDescription> contains a short explanatory summary of the accessibility of the product, consistent with the more specific conformance and feature details provided. The summary should note both the accessibility features provided and any potential deficiencies. More detailed information may be provided in an external file using codes 94–96. For use in ONIX 3.0 only

This value is the same as the Schema.org accessibilitySummary property.

The field is often limited to only 500 characters.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>00</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
   Publication lacks image descriptions and alt text.
 </ProductFormFeatureDescription>
</ProductFormFeature>

01: LIA Compliance Scheme

Indicates that the EPUB conforms to the Libri Italiani Accessibili guidelines.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>01</ProductFormFeatureValue>
</ProductFormFeature>

02: Accessibility Specification 1.0 A

Conforms with the requirements of EPUB Accessibility Spec 1.0 and WCAG level A. <ProductFormFeatureDescription> may carry a URL linking to a compliance report or certification provided by an independent third party certifier. In the absence of a URL, conformance with the requirements of the Accessibility Specification is self-certified by the publisher.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>02</ProductFormFeatureValue>
</ProductFormFeature>

03: Accessibility Specification 1.0 AA

Conforms with the requirements of EPUB Accessibility Spec 1.0 and WCAG level AA. <ProductFormFeatureDescription> may carry a URL linking to a compliance report or certification provided by an independent third party certifier. In the absence of a URL, conformance with the requirements of the Accessibility Specification is self-certified by the publisher.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>03</ProductFormFeatureValue>
</ProductFormFeature>

09: Inaccessible

Known to lack significant features required for broad accessibility. For use in ONIX 3.0 only.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>09</ProductFormFeatureValue>
</ProductFormFeature>

10: No user agent accessibility options disabled (except)

No accessibility features offered by the reading system, device or reading software (including but not limited to choice of text size or typeface, choice of text or background color, text-to-speech) are disabled, overridden or otherwise unusable with the product EXCEPT – in ONIX 3 messages only – those specifically noted as subject to restriction or prohibition in <EpubUsageConstraint>. Note that provision of any significant part of the textual content as images (ie as pictures of text, rather than as text, and without any textual equivalent) inevitably prevents use of these accessibility options.

Digital rights management (DRM) restrictions sometimes allow content producers to enable or disable features that impact the accessibility of a publication. To meet the criteria, do not bundle or distribute publications with restrictions on them that would disable access to the content by screen readers.

The following example shows an EPUB publication that prohibits text-to-speech playback.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>10</ProductFormFeatureValue>
</ProductFormFeature>
…
<EpubUsageConstraint> 
 <EpubUsageType>05</EpubUsageType> 
 <EpubUsageStatus>03</EpubUsageStatus>
</EpubUsageConstraint>

11: Table of contents navigation

Table of contents allows direct (eg hyperlinked) access to all levels of text organization above individual paragraphs (eg to all sections and subsections) and to all tables, figures, illustrations etc. Non-textual items such as illustrations, tables, audio or video content may be directly accessible from the Table of contents, or from a similar List of illustrations, List of tables, etc.

The requirement to include an EPUB navigation document does not, in and of itself, satisfy this requirement. A toc nav with links to the complete structure of the publication is required. See the Table of Contents section for more information.

See also the Content Lists for expressing lists of tables, illustrations, and the like.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>11</ProductFormFeatureValue>
</ProductFormFeature>

12: Index navigation

Index provides direct (eg hyperlinked) access to uses of the index terms in the document body.

Refer to the Indexes section for more information on tagging indexes.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>12</ProductFormFeatureValue>
</ProductFormFeature>

13: Reading order

All or substantially all textual matter is arranged in a single logical reading order (including text that is visually presented as separate from the main text flow, eg in boxouts, captions, tables, footnotes, endnotes, citations, etc). Non-textual content is also linked from within this logical reading order. (Purely decorative non-text content can be ignored).

The required spine element in the EPUB package document does not satisfy this requirement alone. The logical reading order of the publication must be clearly delineated in the markup. Footnotes, tables, images, sidebars and all similar secondary content must be marked up so that it can be skipped over.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>13</ProductFormFeatureValue>
</ProductFormFeature>

14: Short alternative descriptions

All or substantially all non-text content has short alternative (textual) descriptions, usually provided via alt attributes. Note this applies to normal images (eg photographs, charts and diagrams) and also to any embedded audio, video etc. Audio and video content should include alternative descriptions suitable for hearing-impaired as well as for visually-impaired readers. (Purely decorative non-text content can be ignored, but the accessibility of resources delivered via a network connection rather than as part of the e-publication package must be included).

Refer to the Images section for more information.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>14</ProductFormFeatureValue>
</ProductFormFeature>

15: Full alternative descriptions

All or substantially all non-text content has full alternative (textual) descriptions. Note this applies to normal images (eg photographs, charts and diagrams) and also to any embedded audio, video etc. Audio and video content should include full alternative descriptions (eg audio-described video) and transcript, subtitles or captions (whether closed or open) suitable for hearing-impaired as well as for visually-impaired readers. (Purely decorative non-text content can be ignored, but the accessibility of resources delivered via a network connection rather than as part of the e-publication package must be included).

See the Image Descriptions, Audio, and Video sections for more information on meeting this requirement.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>15</ProductFormFeatureValue>
</ProductFormFeature>

16: Visualised data also available as non-graphical data

Where data visualisations are provided (eg graphs and charts), the underlying data is also available in non-graphical (usually tabular, textual) form.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>16</ProductFormFeatureValue>
</ProductFormFeature>

17: Accessible math content

Mathematical content such as equations is usable with assistive technology, eg through use of MathML. Semantic MathML is preferred but Presentational MathML is acceptable.

Although the definition states that Semantic MathML is preferred, there is no support for Semantic MathML in web user agents, such as EPUB reading systems, so providing Presentational MathML is generally all that is possible.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>17</ProductFormFeatureValue>
</ProductFormFeature>

18: Accessible chem content

Chemistry content such as chemical formulae is usable with assistive technology, eg through use of ChemML.

EPUB does not provide native support for ChemML. The epub:switch element for allowing other grammars is also now deprecated.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>18</ProductFormFeatureValue>
</ProductFormFeature>

19: Print-equivalent page numbering

For a reflowable e-publication, contains references to the page numbering of an equivalent printed product. Use <RelatedProduct> with relation code 13 to specify an identifier for the source of the page numbers.

Refer to the Page Numbering and Page List Navigation sections for more information.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>19</ProductFormFeatureValue>
</ProductFormFeature>
…
<RelatedProduct>
  <ProductRelationCode>13</ProductRelationCode>
  <ProductIdentifier>
   <ProductIDType>15</ProductIDType>
   <IDValue>9780123456789</IDValue>
 </ProductIdentifier>
 <ProductForm>BB</ProductForm>
</RelatedProduct>

20: Synchronised pre-recorded audio

Text-synchronised pre-recorded audio narration (natural or synthesised voice) is included for substantially all textual matter, including all alternative descriptions.

For EPUB 3, the inclusion of media overlays to synchronize text and audio content is sufficient to meet this requirement.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>20</ProductFormFeatureValue>
</ProductFormFeature>

21: Text-to-speech hinting provided

Text-to-speech has been optimised through provision of PLS lexicons, SSML or CSS Speech synthesis hints.

These technologies are not currently supported in EPUB 3 reading systems.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>21</ProductFormFeatureValue>
</ProductFormFeature>

22: Language tagging provided

The language of the text has been specified (eg via the HTML or XML lang attribute) to optimise text-to-speech (and other alternative renderings), both at whole document level and, where appropriate, for individual words, phrases or passages in a different language.

For more information, refer to the Language section of the knowledge base.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>22</ProductFormFeatureValue>
</ProductFormFeature>

24: Dyslexia readability

Specialised font, character and/or line spacing, justification and paragraph spacing, coloring and other options provided specifically to improve readability for dyslexic readers. Details, including the name of the font if relevant, should be listed in <ProductFormFeatureDescription>

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>24</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	Publication uses the Open Dyslexic font …
 </ProductFormFeatureDescription>
</ProductFormFeature>

25: Use of color

For readers with color vision deficiency, use of color (eg in diagrams) is not the sole means of graphical distinction.

Corresponds to WCAG Success Criterion 1.4.1 - Use of Color.

Note that this property is for visual reading. The methods for passing it do not ensure that non-visual readers can access the same information.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>25</ProductFormFeatureValue>
</ProductFormFeature>

26: Use of contrast

Body text is presented with a contrast ratio of at least 4.5:1 (or 3:1 for large/heading text).

Corresponds to WCAG Success Criterion 1.4.3 Contrast (Minimum).

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>26</ProductFormFeatureValue>
</ProductFormFeature>

27: Use of audio

Audio content is presented with no or low background noise (eg ambient sounds), at least 20dB below the level of foreground speech.

Caution

This value appears to correspond to WCAG Success Criterion 1.4.7 Low or No Background Audio, but has introduced wording changes that make its application ambiguous (i.e., it is no longer restricted to audio that is primarily speech). For the purposes of setting this value, it is advised to follow the requirements of SC 1.4.7.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>27</ProductFormFeatureValue>
</ProductFormFeature>

28: Full alternative audio descriptions

All or substantially all non-text content has full alternative descriptions as pre-recorded audio. Note this applies to normal images (eg photographs, charts and diagrams) and also to any embedded video etc. Video content should include full alternative descriptions (eg audio-described video) and transcript, subtitles or captions (whether closed or open) suitable for hearing-impaired as well as for visually-impaired readers. (Purely decorative non-text content can be ignored, but the accessibility of resources delivered via a network connection rather than as part of the e-publication package must be included).

Caution

The ONIX description of this value is ambiguous. It is not clear whether the narration of descriptions in media overlays is acceptable, for example. It is also not clear when a publication "substantively" meets the requirements, or why the description also adds recommendations for transcripts, etc. that are already covered by value 15.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>28</ProductFormFeatureValue>
</ProductFormFeature>

29: Next / Previous navigation

All levels of heading and other structural elements of the content are correctly marked up and (if applicable) numbered, to enable fast next heading / previous heading, next chapter / previous chapter navigation without returning to the table of contents.

Caution

The application of this value is currently unclear. It may be that using heading tags is sufficient, or it may also require the use of ARIA roles.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>29</ProductFormFeatureValue>
</ProductFormFeature>

The following informational fields should always be included when applicable:

93: Compliance certification by

<ProductFormFeatureDescription> carries the URL of a web page belonging to the organisation responsible for compliance testing and certification of the product – typically a ‘home page’ or a page describing the certification scheme itself. For use in ONIX 3.0 only.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>93</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	http://standards-org.example.com/
 </ProductFormFeatureDescription>
</ProductFormFeature>

94: Compliance web page for detailed accessibility information

<ProductFormFeatureDescription> carries the URL of a web page giving further detailed description of the accessibility features, compatibility, testing, certification etc relevant to this product. The web page should be maintained by an independent compliance scheme or testing organization.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>94</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	http://standards-org.example.com/book/123/compliance
 </ProductFormFeatureDescription>
</ProductFormFeature>

95: Trusted intermediary’s web page for detailed accessibility information

<ProductFormFeatureDescription> carries the URL of a web page giving further detailed description of the accessibility features, compatibility, testing etc relevant to this product. The web page should be provided by a trusted intermediary or third party nominated by the publisher.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>95</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	http://intermediary.example.com/book/123/compliance
 </ProductFormFeatureDescription>
</ProductFormFeature>

96: Publisher’s web page for detailed accessibility information

<ProductFormFeatureDescription> carries the URL of a web page giving further detailed description of the accessibility features, compatibility, testing etc relevant to this product. The web page should be provided by the publisher.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>96</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	http://publisher.example.com/book/123/compliance
 </ProductFormFeatureDescription>
</ProductFormFeature>

97: Compatibility tested

<ProductFormFeatureDescription> carries the URL of a web page giving a short description of compatibility testing carried out for this product, including detailed compatibility with various assistive technology such as third-party screen-reading software. See also code 00 for a summary of the accessibility features of the product itself.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>97</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	Content has been tested to work on iBooks,
	Sony User and Adobe Digital Editions in 
	both scripting enabled and disabled modes.
 </ProductFormFeatureDescription>
</ProductFormFeature>

98: Trusted Intermediary contact

<ProductFormFeatureDescription> carries the e-mail address for a contact at a ‘trusted intermediary’, to whom detailed questions about accessibility for this product may be directed.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>98</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	accessinfo@global-library.example.com
 </ProductFormFeatureDescription>
</ProductFormFeature>

99: Publisher contact for further accessibility information

<ProductFormFeatureDescription> carries the e-mail address for a contact at the publisher to whom detailed questions about accessibility of this product may be directed.

<ProductFormFeature>
 <ProductFormFeatureType>09</ProductFormFeatureType>
 <ProductFormFeatureValue>99</ProductFormFeatureValue>
 <ProductFormFeatureDescription>
	accessibility-officer@example.com
 </ProductFormFeatureDescription>
</ProductFormFeature>

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