Entities in Attribute Values

Arjun Ray aray at q2.net
Fri Jun 13 06:51:45 BST 1997

On Thu, 12 Jun 1997, David Schach wrote:

> Because entity references are allowed inside ot attribute values, it is
> not possible to store an unmodified URL with data in an attribute.  For
> example, the following XML is not valid because the '&''s are not
> escaped inside of SELF's HREF value.  

This is a problem only if '&' *must* be the field separator. Why not
something else,, like ';' ?

> 	<SELF
> HREF="http://someserver/scripts/oleisapi2.dll/comics.custom.cdf?comics=o
> n&dilbert=on&calvin=on&peanuts=on" />
> This makes it inconvenient to store URL's in XML files.  Would it anyone
> be interested in changing entity processing to fix this?

IMHO, there's no need for that. Or, at any rate, there shouldn't be. Using
'&' as a field separator in "query URLs" is a historical artefact of lack
of RTFM. The problem was recognized reasonably early too, and a fix was
proposed, but no HTML browser implementor of, ah, consequence ever got a
Round Tuit. 

>From RFC 1866, Section 8.2.1 "The form-urlencoded Media Type":

           NOTE - The URI from a query form submission can be
            used in a normal anchor style hyperlink.
            Unfortunately, the use of the `&' character to
            separate form fields interacts with its use in SGML
            attribute values as an entity reference delimiter.
            For example, the URI `http://host/?x=1&y=2' must be
            written `<a href="http://host/?x=1&#38;y=2"' or `<a

            HTTP server implementors, and in particular, CGI
            implementors are encouraged to support the use of
            `;' in place of `&' to save users the trouble of
            escaping `&' characters this way.
We're not committed to perpetauting mistakes, are we?


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