Clarification of XLink position with HTML and legacy formats.

Below is text for a clarification of XLink position with HTML and
legacy formats.

The original requirements of XLink include representing the HTML
hyperlinks conveyed by the HREF and SRC attributes, and enabling any
XML document to have its hyperlink semantics recognized, regardless of
its syntax.  The first requirement is written as

  "An XML link must provide a straightforward way of representing an HTML
  <A> or <IMG> link. Automated translation of HTML links to XML links
  must be possible."

The second requirement is written as

  "It must be possible to apply XML link semantics to existing
  documents by modifying the documents' DTDs only, requiring no
  modification to the document instances themselves."

The XML Linking working group has since made the decision
not to meet these requirements.  This decision is based on the group's
consensus that the technical means for meeting these requirements do
not exist, and it is outside of scope and capabilities of the XML
Linking working group to specify these technical means.

These original requirements indicate enabling hyperlinks of many
syntaxes to be uniformly recognized as XLinks.  An XLink specification
meeting these requirements would define hyperlinking semantics that
documents of many XML-defined syntaxes could have their hyperlinking
constructs mapped to.  Because the necessary remapping mechanisms are
not available, this XLink specification instead specifies not just the
semantics but also the syntax that XML documents need to conform to
have their hyperlinks recognized as XLinks.  The syntactic
requirements of XLink documents are stricter than they would have been
if all the requirements were able to be met.

This means that existing XML documents cannot be made to have their
hyperlinks recognized as XLinks.  It also means that document sets
with syntactic requirements that conflict with XLink syntax will not
be able to use XLink.  The XHTML recommendation defines such a
document set -- XHTML does not conform to XLink.  The current working
draft for SMIL Boston also does not conform to XLink for the same
reasons.  Developers of other upcoming XML document sets may similarly
decide they cannot use the XLink syntax.

--
Lloyd Rutledge  vox: +31 20 592 41 27       fax: +31 20 592 41 99
CWI             net: Lloyd.Rutledge@cwi.nl  Web: http://www.cwi.nl/~lloyd
Post:   PO Box 94079   |  NL-1090 GB Amsterdam  |  The Netherlands
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Received on Thursday, 17 February 2000 10:29:07 UTC