Because neither event handler is triggered by any user interaction with an element on
the page, they do not present accessibility problems.
onChange This event handler is very commonly used for triggering JavaScript
functions based on a selection from within a
tremendous accessibility problems for many commonly used screen readers and should
be avoided. Instead, web developers should use the onClick event handler (associated
with a link or button that is adjacent to a
onBlur and onFocus These event handlers are not commonly used in web pages.
While they don t necessarily present accessibility problems, their behavior is confusing
enough to a web page visitor that they should be avoided.
(m) When a web page requires that an applet, plug in or other application be present on
the client system to interpret page content, the page must provide a link to a plug in or
applet that complies with 1194.21(a) through (l).
Why is this provision necessary?
While most web browsers can easily read HTML and display it to the user, several private
companies have developed proprietary file formats for transmitting and displaying special
content, such as multimedia or very precisely defined documents. Because these file formats
are proprietary, web browsers cannot ordinarily display them. To make it possible for these files
to be viewed by web browsers, add on programs or "plug ins" can be downloaded and installed
on the user s computer that will make it possible for their web browsers to display or play the
content of the files. This provision requires that web pages that provide content such as Real
Audio or PDF (Adobe Acrobat s Portable Document Format) files also provide a link to a plug in
that will meet the software provisions. It is very common for a web page to provide links to
needed plug ins. For example, web pages containing Real Audio almost always have a link to a
source for the necessary player. This provision places a responsibility on the web page author
to know that a compliant application exists, before requiring a plug in.
How can plug ins and applets be detected?
Plug ins can usually be detected by examining a page s HTML for the presence of an
Like plug ins, applets can also be identified by the presence of an
source for a web page. Also, an
web page.
(n) When electronic forms are designed to be completed on line, the form shall allow
people using assistive technology to access the information, field elements, and
functionality required for completion and submission of the form, including all directions
and cues.
Why do electronic forms present difficulties to screen readers?
Currently, the interaction between form controls and screen readers can be unpredictable,
depending upon the design of the page containing these controls. HTML forms pose
accessibility problems when web developers separate a form element from its associated label
or title. For instance, if an input box is intended for receiving a user s last name, the web
National GACC Website and GACC Website Template
37
Implementation Guidelines