Accessibility Metadata: What it is and Why it Matters

For many, searching, finding, and finally reading that really good book is a familiar, pleasurable experience. We stroll through the bookstore (or online), search for a specific title or browse the new releases, make our purchase, and dive into the story. But what if you are blind and depend on assistive technology? Suddenly, that simple journey becomes a complex series of questions. Will this ebook work with my screen reader? Will I be able to "see" the images through descriptive text? Can I navigate by page number? Will the reading order make sense, or will crucial information be delivered out of context, potentially causing confusion or misunderstanding? These are just a few of the accessibility hurdles blind and low-vision readers face when enjoying digital publications.

This is where accessibility metadata comes in. Accessibility metadata is structured information that details a content's accessibility features. It makes finding compatible content easier for users of assistive technologies (such as screen readers, dynamic braille, and text-to-speech devices). Accessibility metadata is focused explicitly on describing a resource's accessibility features, while metadata can describe any aspect of a resource.

Accessibility metadata also provides a standardized method for describing accessibility features and promoting consistency across publications and publication platforms within the publishing industry. This standardization is crucial for interoperability, allowing various software and devices to interpret and use the metadata.

Accessibility Metadata Functions

Accessibility meta provides three specific functions within digital documents and various publishing platforms:

Discoverability: Helps users find publications that meet their specific accessibility needs (e.g., scalable print, audio descriptions, captions).

Usability: Informs users about a publication's accessibility features, allowing them to make informed decisions about whether it will work for them and their specific assistive technology. It informs users of potential dangers, such as flashing content, motion simulations, or uncomfortable sounds.

Interoperability: Enables systems and software to understand and process accessibility information across different platforms and devices. It also helps users determine whether the content meets standards like the Web Content Accessibility Guidelines (WCAG) or EPUB Accessibility Guidelines.

Types of Accessibility Metadata

Structural: Describes the organization and structure of the publication (e.g., headings, lists, tables).

Content: Provides information about the content itself (e.g., alternative text for images, transcripts for audio).

Technical: Specifies the technical features that support accessibility (e.g., font size, color contrast, keyboard navigation).

Conformance: Indicating the level of accessibility compliance (e.g., WCAG conformance).

Where is Accessibility Metadata Found?

Depending on the type of digital content, accessibility metadata can be embedded in various places or exist independently of the content:

Within HTML code: Accessibility metadata is often included in the HTML markup for web pages using specific attributes (e.g., the alt attribute for images and ARIA attributes for dynamic content).

In the document properties: Accessibility metadata can be stored in document properties. For PDFs and other document formats, this metadata provides information about the document's structure and accessibility features.

As separate files: Sometimes, accessibility metadata is stored in separate files (e.g., sidecar files for captions) linked to the main content. Accessibility metadata inside a digital publication or a corresponding sidecar file has essential accessibility claims. These claims help users find and determine whether the publication meets their specific accessibility needs.

Within multimedia files: For some types of audio and video content, accessibility metadata can be embedded directly in the file, providing information about captions, transcripts, and alternative audio descriptions.

Where Can I Find Accessibility Metadata Specifications?

There are three main sets of specifications for accessibility metadata:

EPUB Accessibility 1.1: A popular ebook format that supports embedding accessibility metadata. "This specification defines the requirements for EPUB® Publications to be considered accessible, including both content conformance and metadata requirements for discoverability."

ONline Information EXchange (ONIX): ONIX is a "standard template that organizes electronic book information and is hosted in its own XML file. ONIX messages are formed by codelists that group together information with shared semantics and provide them with numerical values. Codelist 196 contains EPUB accessibility details that provide information on an EPUB’s accessibility features."

Schema.org CreativeWork class: This is a "set of properties used to identify the accessible qualities of a publication. This metadata can be expressed in HTML documents using RDFa or microdata attributes to identify the accessible qualities of the content (e.g., videos). It can also be included in the EPUB package document to provide an overall picture of the accessibility of the given rendition of the publication."

While all three sets of specifications provide ways to include accessibility metadata, there are some key differences. Schema.org CreativeWork is the broadest application, covering a wide range of content types. It is primarily used for search engine optimization and discoverability. EPUB focuses specifically on ebooks, while ONIX is primarily used for books in the publishing industry.

Why is accessibility metadata necessary?

Accessibility metadata opens content to a broader audience, enabling effective search, location, access, and utilization of resources in diverse formats.
It makes publications more usable for people with disabilities.
It provides users with the information they need to make informed decisions about which publications to use.
Helps publishers meet accessibility requirements and regulations.

While all metadata plays a vital role in describing digital content, accessibility metadata stands apart. It directly impacts the usability of digital publications and resources for individuals with visual impairments, empowering them to engage fully and fostering a more inclusive and equitable experience.

Resources

A human author creates the DubBlog posts. The AI tool Gemini is sometimes used to brainstorm subject ideas, generate blog post outlines, and rephrase certain portions of the content. Our marketing team carefully reviews all final drafts for accuracy and authenticity. The opinions and perspectives expressed remain the sole responsibility of the human author.