Comments, parsers, XPointers

David Megginson ak117 at
Wed May 20 19:32:37 BST 1998

John E. Simpson writes:

 > >From previous (sometimes contentious) discussions on this list, I gather
 > that there's no provision in SAX for passing document <!-- comments --> to
 > a downstream application.
 > The XPointer WD, production 12, allows for relative addressing by node type
 > (element, PI, and so on), *including* comments.
 > Does the downstream invisibility of comments imply that a URL like this
 > will always fail?
 > 	somedoc.xml#child(1,#comment)

With SAX level 1, it does.  I had a very interesting e-mail discussion
with Eve and Steve about the whole issue of pointing at comments, and
it will interesting to see how that develops in the next draft.  The
DOM includes the comments to support authoring tools, but I imagine
that many (most?) DOM builders will simply discard the comments before
constructing the tree (comments have no purpose on the
production/browsing side).

In the longer term, what we need is an official definition of an XML
information set, specifying (for example) that reporting comments is
optional, while reporting the start and end of elements is required.
Once such a beastie exists, many vexing questions about (and
inconsistencies among) the DOM, XPointers, SAX, XSL, etc. will

All the best,


David Megginson                 david at

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