HTML and CSS Reference
In-Depth Information
Frame Sites
When a nonvisual browser opens a frame site, it can render the contents of only one
frame at a time. Users are given a choice of which frame to open. So, it's important that
the name given to a frame indicate the frame's content. For this reason, the Section 508
guideline for frames states that
§1194.22 (i)
Frames shall be titled with text that facilitates frame identifi cation and
navigation.
Frames can be identifi ed using either the title attribute or the name attribute, and dif-
ferent nonvisual browsers use different attributes. For example, the Lynx browser uses
the
name
attribute, while the IBM Home Page Reader uses the
title
attribute. For this
reason, you should use both attributes in your framed sites. If you don't include a
title
or
name
attribute in the frame element, some nonvisual browsers retrieve the document
specifi ed as the frame's source and then use that page's title as the name for the frame.
The following code demonstrates how to make a frame site accessible to users with
disabilities.
<frameset cols=”25%, *”>
ƒƒƒ<frame src=”title.htm” title=”banner” name=”banner” />
ƒƒƒ<frameset rows=”100, *”>
ƒƒƒƒƒƒ<frame src=”links.htm” title=”links” name=”links” />
ƒƒƒƒƒƒ<frame src=”home.htm” title=”documents” name=”documents” />
ƒƒƒ</frameset>
</frameset>
Naturally, you should make sure that any document displayed in a frame follows the
Section 508 guidelines.
Animation and Scrolling Text
Animated GIFs, scrolling marquees, and other special features can be sources of irrita-
tion for any Web user; however, they can cause serious problems for certain users. For
example, people with photosensitive epilepsy can experience seizures when exposed to
a screen or portion of a screen that fl ickers or fl ashes within the range of 2 to 55 fl ashes
per second (2 to 55 Hertz). For this reason, the Section 508 guidelines state that
§1194.22 (j)
Pages shall be designed to avoid causing the screen to fl icker with a
frequency greater than 2 Hz and lower than 55 Hz.
In addition to problems associated with photosensitive epilepsy, users with cognitive
or visual disabilities may fi nd it diffi cult to read moving text, and most screen readers are
unable to read moving text. Therefore, if you decide to use animated elements, you must
ensure that each element's fl ickering and fl ashing is outside of the prohibited range, and
you should not place essential page content within these elements.
Scripts, Applets and Plug-ins
Scripts, applets, and plug-ins are widely used to make Web pages more dynamic and
interesting. The Section 508 guidelines for scripts state that
§1194.22 (l)
When pages utilize scripting languages to display content, or to create
interface elements, the information provided by the script shall be
identifi ed with functional text that can be read by adaptive technology.
