[SpecGL Draft] D5 Error Handling

For the WG

D5. Error Handling?
@@ should we address this? does it belong here?

There's a section right now which is called Error Handling but which is 
not filled. I think it has to be clearly defined because it's part of 
the quality of a technology, though I would like to clear a bit the 
bush before. I guess it would benefit from a wiki topic if not done 
yet.

This is what I have identified as possible places where technologies 
might need "Error Handling".

* Not authorized Syntax
	* Invalid syntax, when a document, for example XHTML, SOAP Envelop, 
etc. Do not respect a DTD or an XML Schema. Though some specifications 
doesn't have a DTD or schema language. For example
	- XSLT
	- CSS (Björn Hörmann is working on a schema for CSS, but outside of 
the CSS WG)


* Extensions
	* This is a tricky case. You could define the technology to be able to 
handle extensions, but give a way for certain classes of Products to 
adopt a particular behavior when:
	+ it meets an extension
		a kind of very strict parser. The spec and only the spec, no 
extension.
	+ it meets an extension which doesn't respect the mechanism defined 
for extension. For example, a CSS parser which will choke on
		sexy-circle
	when it should be
		-sexy-circle, because the spec has defined "-vendor-property" for the 
way to create syntax extension.
		For example, should a user agent ignore every unknown features, for 
example, like in HTML 4.01 and only display the content of the element?
	

* Contradiction with other specifications.
	* For example some technology might redefine the default behavior of 
another technology. For instance, HTML 4.01 and HTTP 1.0, HTML 4.01 
defines iso-8859-1 for HTTP transaction by default when HTTP 1.0 
defines us-ascii. Is HTML 4.01 in this manner an authorized extension 
of HTP 1.0?
	The consequences on error handling is : What a user agent supporting 
HTML 4.01 and HTTP 1.0 in the absence of encoding information should do 
?
	
* Conformance
	* Error Handling is tightly joined to Conformance. A product is 
conformant not only because it has the adequate positive reaction to, 
for instance, a markup, but also because it has the correct behavior 
when something wrong is happening.





-- 
Karl Dubost - http://www.w3.org/People/karl/
W3C Conformance Manager
*** Be Strict To Be Cool ***