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Richard, > -----Original Message----- > From: Richard Tobin [mailto:richard@c...] > Sent: Tuesday, August 21, 2001 3:45 PM > To: tbray@t... > Cc: xml-dev@l... > Subject: Re: Namespaces, schemas, Simon's filters. > > > >OK, I think I get it. Local element types allow the <line> > >element to have different validation rules depending on > >whether it's a child of <matt:music>, <matt:graphics> or > ><matt:text>. Clearly something that DTD's can't do but is > >desirable. > > >I have a question. With schemas, can I arrange for the > ><matt:line> (note it's in a namespace) element to be validated > >differently depending on whether it's a child of <matt:music>, > ><matt:graphics> or <matt:text>? -Tim > > Yes, these are exactly the two cases we're arguing about. A local > element declaration inside the type of matt:music > > <element name="line" form="unqualified"> ... > > locally declares the element line (in no namespace), whereas > > <element name="line" form="qualified"> ... > > locally declares the element matt:line. The default value for "form" > can be set with the elementFormDefault attribute, and the default > default is unqualified. The same goes for attributes, where (in my > opinion) unqualified is a lot more natural. > > There are two points in dispute: whether local elements are good at > all, and whether unqualified ones are (no doubt there is also a view > that *only* unqualified ones are good, but I haven't noticed anyone > arguing that). Actually, while I've argued as to why making local elements unqualified is a good thing from the point of view of what local elements are, no one has given a similar argument for why local elements should be qualified. The arguments in favor of qualifying them have been simply "I don't like unqualified elements because I can't use the namespace to uniquely identify the element" - when namespaces fail to uniquely identify different local elements anyway. Or they've been "I don't like local elements, and I especially don't want them to be unqualified", which scarcely grapples with what a local element is. I would like to see an argument as to why they should be qualified from first principles as I've argued for them to be unqualfied. Matthew
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