Re: What Is Type Augmentation and Should We Be Concerned? (WAS
"Thomas B. Passin" <tpassin@c...> writes: > [Bullard, Claude L (Len)] > > > And it leads back to the question: can a PSVI or TAI/ATI > > be reduced to a transform? Reading the www-tag discussions, > > it seems that XML may become even more complicated and > > less flexible. Type augmentation seems to be an application > > concern, not an XML Infoset concern. The only way I know to > > keep those distinct is to regard augmentation as transformation. > > > > For a given xml document, there are many schemas that could fit it. Among > many possible choices with xml schema, you can choose to use global elements > vs complex types, just as one example. > > Therefore, there is no complex type that uniquely characterizes an element. > Perhaps the same is true of simple types (except for basic strings), since > you can always find other patterns or restrictions that would produce the > same result. > > If this is the case, then it seems to me that type information, and > especially complex type information, cannot be said to be a property of the > document or element in itself. Instead, it is a joint matter between the > document and the schema. If such type information is forced into the > document representation, it could greatly reduce the inherent flexibility > of an xml document to be processed different ways for different purposes. > > It seems to be, then, that type decoration should remain separate from basic > infoset information, which should characterize or model the document based > on its inherent construction. Agree with all the above, cogently argued. > This is another reason - add it to the others - to strive to keep PSVI > separate from the basic infoset of a document. Just checking in case I'm missing something here -- I believe that in the terms described above the W3C XML Schema REC does precisely this -- it is _very_ careful not to change the input (basic) infoset other than by addition, so that with the exception of defaulted attributes (an exception _mandated_ by our charter to reconstruct DTD functionality, I might add), if a processor looks only at 'basic' infoset properties inn a PSVI, they will see exactly the 'basic' infoset input to schema processing. ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2002, part-time member of W3C Team 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@c... URL: http://www.ltg.ed.ac.uk/~ht/ [mail really from me _always_ has this .sig -- mail without it is forged spam]
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