For non-text content that is functional, such as graphical links or buttons, text alternatives identify the purpose or function of the non-text content or,
For non-text content that is used to convey information, text alternatives convey the same information or,
For non-text content that is intended to create a specific sensory experience, such as music or visual art, text alternatives identify and describe the non-text content or,
Non-text content that does not provide information or functionality is marked such that it can be ignored by assistive technology.
Guideline 1.1 (text-equiv) Issues
People who are blind, have low vision, have cognitive disabilities or have trouble reading text for any reason can have the text read aloud to them by assistive technology.
People who are deaf, are hard of hearing, or who are having trouble understanding audio information for any reason can read the text presentation or have it translated and presented as sign language by assistive technology.
People who are deaf-blind can read the text in braille.
Example 1: an image used as a button. (short equivalent for function)
A right arrow icon is used to link to the next slide in a slide show. The text equivalent is "Next Slide," so that a screen reader would read the phrase "Next Slide" and automatically identify it as a link by adding the word link or changing the synthesizer's voice.
Example 2: a data chart. (short label + longer description)
A bar chart compares how many widgets were sold in June, July, and August. The short label says, "Figure one - Sales in June, July and August." The longer description identifies the type of chart or graph, provides a high-level summary of the data comparable to that available from the chart or graph, and provides the data in a table or other accessible format.
Example 3: an animation. (short label + longer description)
An animation shows how to tie a knot. The short label says, "An animation showing how to tie a square knot." The longer explanation describes the hand movements needed to tie the knot.
Example 4: an audio file of a speech. (short label + transcript)
An audio file is embedded in a Web page. The short label says, "Chairman's speech to the assembly." A link to a text transcript is provided immediately after the audio clip.
Example 5: an audio file of a symphony. (short label)
An audio file is embedded in a Web page. The short label says, "Beethoven's 5th Symphony performed by the Vienna Philharmonic Orchestra."
Editorial Note: The WCAG WG has not tackled the definitions of the terms that we are using and acknowledges that we sometimes use terms inconsistently. We need to coordinate our terms and definitions with the WAI Glossary and are working on proposals for a variety of definitions. We have been looking at the UAAG 1.0 glossary and other glossaries within the W3C.
Graphic representations that are created by a spatial arrangement of text characters. Although it can be rendered on a text display, it is not text.
Editorial Note: We need to include a definition of explicit association here.
non-text content includes but is not limited to images, text in raster images, image map regions, animations (e.g., animated GIFs), ASCII art, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. It also includes any text that can not be translated into Unicode.
Note:
Scripts, applets, and programmatic objects are not covered in this definition and are addressed in guideline 4.2.
Editorial Note: We are currently working with Internationalization (I18N) on including references and improved wording related to the WCAG 2.0 definitions for "text" and "character encoding".
Editorial Note: We need to include a definition of text description here.
Editorial Note: We need to include a definition of text label here.
A text alternative
serves the same function as the non-text content was intended to serve.
communicates the same information as the non-text content was intended to convey.
may contain structured content or metadata.
Note:
Text-alternatives should be easily convertible to braille or speech, displayed in a larger font or different colors, fed to language translators or abstracting software, etc.