Accessible Publishing as gain momentum recently as the Ace product has appeared providing a way to identify ePub 3 documents are being accessible to the handicapped. The standards group BISG has also developed standards and tips for ePub 3 use.
The page shows some of the contents of the BISG document on accessibility. See below for how to obtain your own copy.
The BISG Quick Start Guide to Accessible Publishing offers both a succinct introduction to the basics of accessibility and the market advantages to publishers for adopting best practices in creating accessible digital content. It is available in the ePub 3 format and serves as a model of a properly accessible publication.
- Use HTML5 - To benefit all readers, publishers must make use of the native semantics of HTML5, which will enable logical reading order, effective navigation, skipping, and escaping content. HTML5 is the starting point of accessible content and the foundation of digital publishing.
- Use HTML5 headings - Use HTML5 heading tags to navigate easily through the content. Headings should indicate elements such as chapter titles, section headings, and titles within offset or supplementary content. This enables users of all abilities to navigate the content. There are varying opinions about the proper nesting structure of the headings; see Appendix D for more details.
- Use HTML5 tags and ePub 3 structural semantics - Use the native HTML5 semantics wherever possible. Use the EPUB 3 Structural Semantics Vocabulary as defined at http://idpf.org/epub/vocab/structure/ to identify content. For example, the table of contents should be tagged as <nav epub:type="toc">, and a list of definitions in a glossary would be tagged as <dl epub:type="glossary">.
- Provide complete navigation - All important levels of the document structure should be provided in the EPUB 3 navigation document. Including lower-level headings that would not often be included in a table of contents enables users to quickly access a specific section. It is possible to accomplish a very detailed, nested table of contents and a pleasing visual display by using the hidden attributes on some levels of the TOC tree; see Appendix D for more details.
- Provide content in a logical reading order - Content should be placed in the sequence in which it is intended to be read. Do not place elements (such as sidebars and tables that are set apart from the main text flow using CSS and scripting) in a separate file or at the end of the file. Instead, placing these elements in the location where they are meant to be read will ease reading for users of assistive technologies (AT).
- Separate presentation from content - The meaning of the content should be the same both with and without any styles or formatting applied. Do not use visual-only cues such as colored text, font size, or positioning as the only clue to the meaning or importance of a word or section. Text should never be presented as an image, be reordered by CSS, or require scripting to be accessed. Separate CSS from HTML.
- Do not use images to represent tables - Content embedded in an image is not available to visually impaired readers, so tables should not be produced as images. Instead, use proper and complete markup for tabular data, including headers and scope attributes for tables. The use of HTML5 table markup ensures that a screen reader can navigate elements and understand the hierarchical structure within the table, such as column header information. Including “live” tables preserves the fidelity of the table when the font is increased and makes it possible to tab from cell to cell on some readers.
- Use correct markup for decorative images - Decorative images that convey no information should be tagged as decorative so that screen readers will ignore them rather than attempt to voice information about an image that contains no content.
- Use image descriptions for complex, content-rich images - When images are not sufficiently described in the caption or surrounding text, provide a description. When the image is a link, provide alt text to convey the title or function.
- Use page numbers when there is a print equivalent - Page numbers are the primary way to navigate within a print book, so always include them when there’s a print version of the title. It is also important to include the ISBN of the source of the page numbers in the package metadata for the book as well as in the page list in the navigation document.
- Define the language(s) - It helps assistive technologies to know both the primary language of a publication and exceptions where other languages are used. Provide this knowledge by including both the xml:lang and lang attributes in the relevant enclosing elements.
- Consider using the EPUB for Education profile - The EPUB for Education was developed to enable interoperability of rich educational content. EPUB for Education provides helpful guidelines and best practices for accessibility that are applicable to many types of publications, beyond educational resources. Using the EPUB for Education profile guidelines for accessibility metadata, and additional semantics such as learning objectives and assessments ensures a richer, more accessible digital product.
- Use MathML - MathML (Mathematical Markup Language) presents math as textual markup that can be voiced or described automatically. Unfortunately, many reading systems do not currently support MathML. When determining whether to include MathML, it is important to assess the platforms and audiences to which the content will be delivered. Consult the BISG EPUB 3 Support Grid at http://epubtest.org/ to assess current reading system support of MathML.
- Provide alternative access to media content - Captions offer a text transcription of spoken dialogue or audio content to aid users who may have difficulty hearing or are situationally challenged. Described video, on the other hand, contains descriptions of visual actions for users who may have a vision loss. The Described and Captioned Media Center has two references: the Captioning Key and the Description Key. It is also recommended that a full transcript of the captioned video be provided to aid the understanding of those with a cognitive disorder or for non-native speakers.
- Use accessibility metadata - As part of a general good practice of documenting the accessibility of your content, provide ONIX and Schema.org accessibility metadata in your files so that end users know what features are included, and so that search engines can discover your accessible materials.
- Make sure your processes support the above best practices- Initiate a sustained company-wide effort to make accessibility a core value in the production and dissemination of content, including development of a company policy statement to express the accessibility commitment.