[Bug 5744] New: Improved Fragment Identifiers


           Summary: Improved Fragment Identifiers
           Product: HTML WG
           Version: unspecified
          Platform: PC
               URL: http://lists.w3.org/Archives/Public/public-
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Spec proposals
        AssignedTo: dave.null@w3.org
        ReportedBy: dret@berkeley.edu
         QAContact: public-html-bugzilla@w3.org
                CC: ian@hixie.ch, mike@w3.org

The recently published HTML 5 draft does not change anything regarding HTML
fragment identifiers. They are still limited to IDs only (with <a name=""> as
alternative for backwards-compatibility). This means that any reference into an
HTML page depends on how the page is using IDs.

But wouldn't HTML 5 be a wonderful opportunity to bring a little bit more
hypermedia back to the Web? XML had XLink and XPointer. Both were failures for
a number of reasons, but I am still a big fan of trying to make the Web more
hypermedia-like. So why not learn from XPointer and try to give HTML 5 a more
practical and useful set of fragment identification methods than just IDs?

The whole fragment identification idea is a classic chicken and egg problem.
Why use them when they're not supported? Why support them when they're not
used? We had a lot remarks like that when we worked on fragment identifiers for
plain text files, but I still believe it is good to have mechanisms like that.
Assume Firefox had a feature where you just moused over a paragraph,
right-clicked, and then you could send an email with a pointer to that
paragraph. If the receiver had Firefox, the browser would scroll to and
highlight that paragraph. I am still convinced a lot of people would find such
a feature pretty useful. And things would not break in another browser, users
would simply not get the scroll/highlight behavior.

While I am convinced that HTML 5 would be the right point in time to introduce
such an improved fragment identification method and try to fix the fact that
few people use HTML fragment identification, I am not really sure how to best
do it. My guess is there should be three basic ways of identifying fragments:

* IDs: For backwards compatibility, IDs (and <a name="">) should be supported.
It would be what XPointer called barenames or shorthands.

* Child Sequences: Similar to XPointer's child sequence, there should be one in
HTML 5, which could either start at the page body, or at an ID. The fragment
identifier #warning/2/3 would identify the third child of the second child of
the id=warning element.

* Character Pointers: Should there also be a way of how to point to a position?
Maybe defined by counting characters in the page's string value? Hard to tell,
but this is where XPointer definitely went over the top and was never finished,
because it even tried to define arbitrary ranges, which is really hard to do.

Maybe just IDs and child sequences could do the trick? There also should be a
well-defined behavior for browsers, so that a user instructing a browser to
create a fragment identifier could be sure that it will always be rooted at the
nearest ID, to make it less likely to break. I am sure there are many more
details to figure out, but I am curious whether anybody else thinks this could
become a pretty useful addition to how HTML can be used.

And please don't even ask about how to handle situations where CSS is  hiding
parts of the document, maybe dynamically, or even worse, where scripting code
is changing the document's DOM. It would be necessary to have well-defined
behavior for all possible situations, but my guess is that for the majority of
static Web pages, fragment identification in a rather simple form would already
be pretty useful as a way to better communicate about Web content.

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Received on Friday, 13 June 2008 01:28:00 UTC