Appendix H: Accessibility Support
This appendix is informative, not normative.
H.1 WAI Accessibility Guidelines
This appendix explains how accessibility guidelines published by
W3C's Web Accessibility Initiative (WAI) apply to SVG.
- The "Web Content Accessibility Guidelines 1.0"
authors can create Web content that is accessible to people with
- The "Authoring Tool Accessibility Guidelines 1.0"
how developers can design accessible authoring tools such
as SVG authoring tools.
To conform to the SVG specification,
an SVG authoring tool must conform to ATAG (priority 1). SVG support for
element grouping and
reuse is relevant to
designing accessible SVG authoring tools.
- The "User Agent Accessibility Guidelines 1.0"
how developers can design accessible user agents such as
SVG-enabled browsers. To conform to the SVG specification,
an SVG user agent should conform to UAAG. SVG support for
scaling, style sheets, the DOM, and metadata are all relevant to
designing accessible SVG user agents.
The W3C Note "Accessibility Features of SVG" [SVG-ACCESS] explains
in detail how the requirements of the three guidelines apply to SVG.
H.2 SVG Content Accessibility Guidelines
This section explains briefly how authors can create accessible SVG
documents; it summarizes "Accessibility Features of SVG" [SVG-ACCESS].
- Provide text equivalents for graphics.
- When the text content of a graphic (e.g., in a
element) explains its function, no text equivalent
is required. Use the
child element to explain the function
elements whose meaning is not clear from their
- When a graphic does not include explanatory
text content, it requires a text equivalent. If the equivalent
is complex, use the
element, otherwise use the
- If a graphic is built from meaningful
parts, build the description from meaningful parts.
- Do not rely on color alone.
- Do not use color alone to convey information.
- Ensure adequate color contrast.
Use style sheets so that users who require certain
color combinations may apply them through user style sheets.
- Use markup and style sheets and do so properly.
- Represent text as character data, not as images or curves.
Style text with fonts. Authors may describe their
own fonts in SVG.
- Separate structure from presentation.
- Use the 'g'
and rich descriptions to structure SVG documents. Reuse
- Publish highly-structured documents, not just graphical
representations. Documents that are rich in structure
may be rendered graphically, as speech, or as braille.
For example, express mathematical relationships
in MathML [MATHML]
and use SVG for explanatory graphics.
- Author documents that validate to the SVG grammar.
- Use style sheets to specify graphical and aural
- Use relative units in style sheets.
- Clarify natural language usage.
- Use xml:lang
to identify the natural language of
content and changes in natural language.
- Ensure that dynamic content is accessible.
- Ensure that text equivalents for dynamic content are updated when the
dynamic content changes.
- Ensure that SVG documents are usable when scripts or other
programmatic objects are turned off or not supported.