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RE: validation errors on pages with query strings in URL?

for

From: Jukka Korpela
Date: May 3, 2002 6:42AM

Mark Bryant wrote:

> When running an HTML validation on a page that
> may have a link on it like
> <a href="examples/page.asp?ID=4">, we typically will get
> Error: unknown entity "ID".

I don't think that particular construction causes a validation error.
Rather, there's something like
<a href="examples/page.asp?foo=bar&ID=4">

> I know this does not make the page inaccessible,

Actually, it might! A construct like &ID is an entity reference. It is
currently undefined by HTML specifications, but it might become defined in
the future, or some browsers might recognize it as a nonstandard entity
reference. And then the link would probably fail.

But this is not specifically an accessibility problem. Rather, a general
HTML authoring issue. The solution is to "escape" any occurrence of the
ampersand character & in data (e.g., in a href value) as &amp;, which is the
entity reference for it. This topic is briefly discussed e.g. at
http://www.htmlhelp.com/tools/validator/problems.html#amp
and partly related reasons for using valid markup are listed at
http://www.htmlhelp.com/tools/validator/reasons.html

--
Jukka Korpela
TIEKE Tietoyhteiskunnan kehitt