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Re: X(HT)ML Fragment Identifiers

From: Erik Wilde <dret@berkeley.edu>
Date: Mon, 09 Jun 2008 14:59:00 -0700
Message-ID: <484DA7A4.6070300@berkeley.edu>
To: public-html@w3.org
CC: Robert J Burns <rob@robburns.com>

hello robert.

thanks for the reply!

> First, you mention XPointer and XLink, but I'm not clear how your 
> suggestion is different from XPointer. BTW, I think is a bit to 
> premature to declare things such as XPointer a failure, though I think 
> its fair to say it has not (yet) taken hold.

my suggestion would be specific for the html media type, whereas 
xpointer applies to xml in general. xpointer is a bit more complex and 
needs to be so, because it has to take namespaces into account, and it 
also was trying to allow arbitrary ranges within xml documents. i think 
it would be better to have something simpler (xpointer now is even a 
modularized spec with several schemes). i think it is fair to say that 
xpointer is a failure, but that certainly is a matter of taste; it 
definitely is not a success...

> Second, what specifically would you want HTML5 to do regarding such 
> pointers. For example, would it be sufficient for HTML5 to 
> encourage/recommend/require HTML5 conforming UAs to support XPointer (by 
> way of reference) or are you suggesting something very different than that.

i would like to create something new and simpler than xpointer, and to 
declare it as the extended fragment identification semantics for html5. 
user agents would be encouraged to support it, and the spec could even 
contain suggested algorithms how to turn points and ranges into html5 
fragment identifiers. with no support in user agents, fragments in html5 
would remain as rarely used as with html4.

> Overall, I think adding such capabilities is usually a big win for 
> authors and users. Especially with so many of the W3Cs recommendations, 
> their abstract and modular nature, enables capabilities and use cases 
> many of us have not yet imagined. I also think this topic is closely 
> related to two other issues that facilitate explicit document markup for 
> document fragments:
>   The issue of id and xml:id and allowing an IDENT data type that 
> facilitates identifying document fragments by element-node paths [1]

@id and @xml:id to me look like entirely different things than what [1] 
describes. @is is covered by html4 fragment identifiers, and the minimum 
extension of html5 fragment identifiers probably should be to also cover 

[1] probably should have been [2], and thanks for pointing to it. the 
IDENT semantics look kind of weird to me, and would be at odds with 
other xml technologies (and suggesting @id should get the IDENT 
semantics looks very wrong to me; html4 defines it as being an ID). but 
anyway, @xml:id should definitely be covered by html5.

>   The issue of including explicit bookmarks (void non-displayed 
> elements) and arbitrary non-hierarchical clippings [2]

aha, [1] and [2] were in the wrong order. well, the clippings talk about 
changing the document, whereas fragment identifiers do not add any 
document markup, they simply define fragment identification semantics.

> Both of these issues facilitate similar goals, but require write access 
> to the document and often needlessly littering the document with extra 
> markup when an XPointer-like pointer would suffice. On the other hand, 
> these two proposals also make it easier and more likely to have nearby 
> ids to root a pointer.

the whole idea of fragment identifers is based on using documents to 
which there is no write access, and on the web, that's the norm. so 
adding more nuanced fragment identifers does not any complexity to html5 
markup, it simply adds a more hypermedia-like way how user agents can 
support access to html documents.

> It also dove-tails nicely with the existing cite attribute which would 
> often reference persistent URLs with static and stable pages (likewise, 
> the proposal to enhance HTML referencing capabilities [3]).

i like the idea to have better quotations in html5. html4 is bad at 
that, and better fragment identification would be a good complement to 
better markup design for quotations.

> To track discussion on this, you might want to alternatively make use of 
> the W3C wiki. It provides a place to edit and refine the issue including 
> adding use cases, possible solutions and collected references. Likewise 
> it provides a persistent URL to refer to the issue. The nice thing about 
> the wiki is it nicely integrates two complementary functions: 1) the 
> revisable wiki page that can reflect the current state of the 
> issue/proposal and 2) it easily links to persistent logs such as a) the 
> official discussion here on the WG mail serve, b) the change log for the 
> wiki page; c) links to IRC or other logged threads on the topic. 
> Bugzilla does not really add much to that (the other problem with 
> buzilla is it bifurcates  or trifurcates  the current deliberations of 
> the WG).

is the wiki official? and how does it relate to bugzilla, which also 
seems to be attempt to turn such an idea into something that has a 
persistent URI? i am willing to create such a page in either the wiki or 
in bugzilla, but i would like to avoid having to do both and having to 
keep both up to date...

thanks again for the comments and kind regards,

erik wilde   tel:+1-510-6432253 - fax:+1-510-6425814
        dret@berkeley.edu  -  http://dret.net/netdret
        UC Berkeley - School of Information (ISchool)
Received on Monday, 9 June 2008 21:59:56 UTC

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