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Section 508 Web Accessibility
- Client-Side Image Maps Guidelines
§1194.22(f) Client-side image maps shall be provided
instead of server-side image maps except where the regions
cannot be defined with an available geometric shape.
Checkpoint
Does the site contain a client-side image map?
Explanation
Image maps incorporate links or script activations into one
graphical image, as opposed to using separate free-standing
graphical image buttons. Client-side image maps utilize the user
agent (e.g. web browser) to determine which region the user has
selected. If necessary, you can determine if the image map is
client-side by looking through the source code for a tag that
begins with the word 'map'.
Checkpoint
Does the page provide alternative links to the Image Map?
Explanation
In the event the object does not properly load on the User Agent
(e.g. web browser), alternate links must be provided.
Guidelines
Section 508 requires that an image map's alternative method be
functional. Provide a link to a navigation bar or the actual
links:
<OBJECT data="navbar1.gif" type="image/gif" usemap="#map1">
<MAP name="map1">
<P>Navigate the site.
[<A href="guide.html" shape="rect"
coords="0,0,118,28">Access Guide</A>]
[<A href="shortcut.html" shape="rect"
coords="118,0,184,28">Go</A>]
[<A href="search.html" shape="circle"
coords="184.200,60">Search</A>]
[<A href="top10.html" shape="poly"
coords="276,0,276,28,100,200,50,50,276,0">Top Ten</A>]
</MAP>
</OBJECT>
However, there are some circumstances where an image map might not
be rendered by the User Agent. Also, some User Agents do not
render content that is placed inside <object> tags.
Therefore, it is strongly recommended that alternate links and/or
text be placed separately.
Checkpoint
Do the <area> tags contain an alt attribute?
Explanation
Link regions on a client-side image map are treated exactly like
free-standing graphic images in the respect that they must contain alt
attributes.
Guidelines
If the link region contains a text reference (e.g. the region
leading to a search function page might simply say "Search"), the
alt attribute should, at the very least, match the wording on the
image.
If the link region contains an image (e.g. a link to a search
function page might have a picture of binoculars or a magnifying
glass), the alt attribute must match the destination or the
function that is inferred by the image.
Although some alt descriptions can be expanded (e.g. the alt value
for the region leading to a search function can say: "Search the
entire site"), it is highly recommended that the alt values are
kept brief; not all User Agents and assistive technologies can
handle lengthy alt values.
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