RDDL for describing fragment identifier facilities

["Simon St.Laurent" <simonstl@simonstl.com>]

RDDL [1] took a rather different tack from my long-ago XPDL [2] in 
describing resources appropriate to rather than processing requirements for 
documents.  RDDL's design doesn't mandate the inclusion of particular types 
of information, nor does it attempt to address a wide variety of 
interoperability issues raised by issues within the XML family of 
specifications.

I'm wondering if those kinds of information can still be expressed in RDDL, 
however.

In particular, I'm wondering if it's possible to express things like the 
fragment identifier approaches that are appropriate to a particular content 
type, going beyond the limited facilities proposed by Section 5 of RFC 3023 
[3]. Fragment identifier diversity was a difficult issue on the 
ietf-xml-mime mailing list during the creation of RFC 3023, especially 
since some vocabularies (notably SVG [5]) support only the 'bare ID' of 
XPointer [6], one flavor of ID-based XPointer, and an extension, SVG Views, 
which uses the svgView scheme.

It seems like RDDL could provide information regarding which fragment 
identifier facilities are appropriate to content in a given 
namespace.  This could make it possible, for instance, for svgView fragment 
identifiers to operate properly on SVG embedded inside of other XML content 
for which the svgView scheme would be inappropriate.

Developers would have to identify these resources on a per-namespace basis, 
but the information would at least be available in some standardized 
form.  Ideally, fragment identifier schemes might themselves have RDDL 
documents describing their operation and pointing to resources for 
implementing them.


[1] - Resource Directory Description Language (RDDL) - http://www.rddl.org
[2] - XML Processing Description Language (XPDL) - 
http://purl.oclc.org/NET/xpdl
[3] - XML Media Types - http://www.ietf.org/rfc/rfc3023.txt
[4] - ietf-xml-mime mailing list archives - http://www.imc.org/ietf-xml-mime/
[5] - SVG Linking - http://www.w3.org/TR/SVG/linking.html#LinksIntoSVG
[6] - XPointer - http://www.w3.org/TR/xptr

Simon St.Laurent - Associate Editor, O'Reilly & Associates
XML Elements of Style / XML: A Primer, 2nd Ed.
XHTML: Migrating Toward XML
http://www.simonstl.com - XML essays and books