Explanation

A visual sufficient access mode value indicates that a publication can be read, in whole or in part, if the user is able to visually perceive the content. It is expressed in metadata using the visual value.

A visual value mostly commonly indicates that a publication contains images and/or videos, but it is also used if the presentation must be visually perceived to be understood.

If only a single visual sufficient access mode is set, it indicates that only sighted readers will be able to read the content (i.e., the content is not universally accessible). Examples of publications with only a single visual sufficient access mode include comics, manga, and photo books.

When combined with other values, a visual sufficient access mode indicates that some essential content is only readable in visual form. It is most common to find the visual value paired with textual as one means of reading the content, with a single textual value to indicate that there are affordances that allow all the visual content to also be read textually. Any book that is predominantly text-based but includes images, video, interactive games, or other visual content will have both these values set.

For example, an EPUB 3 publication with both textual and visual content that also has a single textual access mode would list the following possibilities:

<meta property="schema:accessModeSufficient">textual, visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>

A single visual sufficient access mode is common in accessible publications produced using the EPUB format but would never apply to an audiobook.

Note that the visual content indicators that can be specified as access modes are never listed as sufficient access modes. Only the visual value is specified, as this value should always be paired with the content indicators.

Note

An edge case can arise with the colorDependent indicator when it is used to specify that textual styling may not be accessible only to users who are color blind (e.g., hyperlinks may not be perceivable). Such publications are not accessible as they will fail WCAG success criterion 1.4.1, but they typically still provide a sufficient textual access mode for non-visual readers.

When the color perception issue is limited only to visual reading, indicate the problem in an accessibility summary and specify that there is single textual sufficient access mode in addition to a visual and textual one.

Examples

Example 1 — EPUB 3
<meta property="schema:accessModeSufficient">textual,visual</meta>
<meta property="schema:accessModeSufficient">textual</meta>
Example 2 — EPUB 2
<meta name="schema:accessModeSufficient" content="textual,visual"/>
<meta name="schema:accessModeSufficient" content="textual"/>
Example 3 — Audiobooks
"accessModeSufficient": [
   {
      "type": "ItemList",
      "itemListElement": ["auditory", "visual"],
      "description": "Audio and images"
   }
]

ONIX Mapping

ONIX currently does not include a means of expressing sufficient access modes.

Related Links