John Cowan wrote:
Rick Jelliffe wrote:
I am confused about a related question: I have heard somewhere that
the XPointer group was going to make XPointers only valid for pointing
into XML documents. So, for example, it would not be legitimate for
an XPointer to point into a WebCGM document or other structured data. Is
this true?
Since XPointers refer explicitly to element trees with attributes,
an XPointer into CGM (which is a binary format) wouldn't make
much sense.
Right. And WebCGM defines its own fragment syntax (which was heavily
inspired by XLink, as it happens).
The real issue is whether XPointers can point into
things like SMIL documents, which "just happen" to be encoded
in XML.
When a new media type is registered, that registration gets to define
what sa fragment identifier means.
So, the language in the XPointer draft is clearly saying, for text/xml
and application/xml, this is the syntax. It doesn't say anything about
other media types, presumably because it can't speak for them.
Other media types can define their own fragment identifiers, which may
have very different requirements to Xlink or may have exactly the same
ones. So they might well say that they use XLink, too.
Or they might say something like "we will allow only links to a given
ID but we will use the exact same syntax XPointer uses for that, for
compatibility". In other words, all valid fragment identifiers for thast
type would use XLink, but not all possible uses of XLink would be valid
for that media type.
--
Chris