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" [WCAG]
explains how authors can create Web content that is
accessible to people with disabilities.
The "Authoring Tool Accessibility Guidelines 1.0" [ATAG] explains 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" [UAAG] explains 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
When the text content of a graphic (e.g., in a 'text' element)
explains its function, no text equivalent is required.
Use the 'title' child element
to explain the function 'text' elements whose
meaning is not clear from their text content.
When a graphic does not include explanatory text
content, it requires a text equivalent. If the
equivalent is complex, use the 'desc' 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
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' element and rich
descriptions to structure SVG documents. Reuse named
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
Ensure that dynamic content is
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