- From: Dominique Hazaël-Massieux <dom@w3.org>
- Date: Fri, 02 Jul 2004 11:38:23 +0200
- To: Karl Dubost <karl@w3.org>
- Cc: www-qa-wg@w3.org
- Message-Id: <1088761103.29343.78.camel@stratustier>
Le mer 30/06/2004 à 22:07, Karl Dubost a écrit : > * 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. Note that you can have an invalid syntax, even if there is no formal language that describes the said syntax; it's easier to check whether the syntax is followed when it is formally described, but that's not a necessity. > For example > - XSLT > - CSS (Björn Hörmann is working on a schema for CSS, but outside of > the CSS WG) (which doesn't prevent to identify "invalid" XSLT or CSS style sheets) > > * 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 (actually, it won't choke, since CSS "forward compatible parsing" theory says to just ignore it) > 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? (see mustIgnore vs mustUnderstand in the wiki topic http://esw.w3.org/topic/ErrorHandling) > * 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. The story is actually different: the HTTP protocol defines iso-8859-1 as the default encoding for text/* when no encoding is specificed; the HTML spec says to ignore that and that you must specify an encoding. http://www.w3.org/TR/1999/REC-html401-19991224/charset.html#spec-char-encoding http://www.ietf.org/rfc/rfc2854.txt (section 6) > Is HTML 4.01 in this manner an authorized extension > of HTTP 1.0? definitely not; contradicting a specification you rely doesn't make you an extension :) > 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 > ? "In addition to this list of priorities, the user agent may use heuristics and user settings. For example, many user agents use a heuristic to distinguish the various encodings used for Japanese text. Also, user agents typically have a user-definable, local default character encoding which they apply in the absence of other indicators." http://www.w3.org/TR/1999/REC-html401-19991224/charset.html#spec-char-encoding > * 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. Good point, indeed. Dom -- Dominique Hazaël-Massieux - http://www.w3.org/People/Dom/ W3C/ERCIM mailto:dom@w3.org
Received on Friday, 2 July 2004 05:39:21 UTC