- From: Jukka K. Korpela <jkorpela@cs.tut.fi>
- Date: Tue, 20 Apr 2004 16:20:44 +0300 (EEST)
- To: www-validator@w3.org
On Tue, 20 Apr 2004, Frank Ellermann wrote: > Another idea would be a "visible with legacy browsers" DTD > designed for new pages trying to be compatible with legacy > browsers. This DTD wouldn't allow size= / face= in <font>, > but require name= corresponding to id= in anchors. Such a requirement is somewhat questionable, since it generally requires considerable modification of nice markup to make it compatible with Netscape 4 class browsers that don't understand id="..." destinations. (That would mean turning <h2 id="foo">xxx</h2> into <h2><a id="foo" name="foo">xxx</a></h2>.) I mention this in this context just to point out that such issues are controversial, and there's no widely acceptable definition of what should be allowed in "legacy DTD". Naturally you can write your own DTD that allows exactly what you wish to allow. If I had a little more spare time I would write a utility that lets you specify "features" to be included or excluded, via a simple form interface, and generates a DTD corresponding to it. Maybe someone else wishes to do that? Then there would be an answer to all requests for various "legacy DTDs". And it could also allow some common extensions like <embed> and <nobr>, if desired. Well, it could allow _any_ element to be disallowed, just in case a person or organization wishes to refrain from using some elements and have checks against accidental use of them. (This would actually be one of the most useful ways of using a markup validator.) > It could eliminate anything which is not essential for new > and simple pages, e.g. only external CSS as in XHTML basic, > no more <center>, but <div align="center"> is still okay, > no <del> without <s>, and some other "XHTML strict" quirks. I don't see why <div align="center"> would be any better than <center>, or why <del> should be used together with <s>, but as regards to validation, the first principle is easily implementable, whereas the latter is a bit more difficult - unless you wish to require exactly that <del> is only allowed with <s> (or <strike>?) as its only content, which is easily describable in a DTD. > For me "transitional" is far too "transitional" and "strict" > is far too "strict". I miss something like "simple", and > it's not the same as "basic". There's a good general point here of course. Authors may wish to avoid certain transitional features and keep using others, maybe changing the division by time, i.e. by moving elements and attributes away from the allowed repertoire. But this is relatively independent of a particular validator. DTDs could be used in any suitable context. What the validator development needs to take note of is the principle that a clear distinction should be drawn between validation and all other activities that checking utility might be involved in. In particular, a validator should simply tell whether a document is valid or not, and report markup errors if not, and _then_ maybe start talking about the weather, or what clothes we should wear, or what HTML design principles we should apply, or whether some heuristics has suggested that the document might syntactically comply with the rules of an SGML application called "HTML". The reason is that documents using customized DTDs can be valid, but not conforming documents (according to the odd rules of HTML that require specific doctype declarations to be used), but it would be rather misleading to say that a document is not valid HTML 4.01, when it (for example) actually complies with HTML 4.01 Strict rules _and_ some additional rules that prohibit presentational features allowed in Struct, _except_ the very rule that requires the use of a specific doctype declaration. -- Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/
Received on Tuesday, 20 April 2004 09:21:01 UTC