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Re: non-authoritative syntaxes for fragment identifiers

From: Graham Klyne <GK@ninebynine.org>
Date: Mon, 06 Sep 2004 17:05:57 +0100
Message-Id: <>
To: Myriam Amielh <myriam.amielh@cisra.canon.com.au>, uri@w3.org

I don't think there any such thing as "non-authoritative fragment 
identifier syntax", and hence don't think the question/suggestion proffered 
is meaningful.

Any URI reference that conforms to the defined syntax is a (syntactically) 
valid URI reference, by definition.  The URI syntax specification is silent 
about how such a URI may be interpreted.  What may or may not be 
"authorized" here is the *interpretetion* of a URI reference containing a 
fragment, and that depends on its circumstance of use (which, I take to be 
the target of the comments in the WWW architecture document).


At 13:31 03/09/04 +1000, Myriam Amielh wrote:

>The issue I would like to submit here is the following: Does the use of a 
>non-authoritative fragment identifier syntax make a URI invalid? In 
>relation to this problem, I have a suggestion for the Last Call on RFC2396bis.
>In the AWWW document, Paragraph 4 of clause 3.3 specifies:
>"Parties that draw conclusions about the interpretation of a fragment 
>identifier based solely on a syntactic analysis of all or part of a URI do 
>so at their own risk; such interpretations are not authoritative because 
>they are not licensed by specification."
>This clause seems to allow the use of a non-authoritative fragment syntax 
>although there is no guarantee it can always be processed. I think it is 
>reasonable to allow the use of non-authoritative fragment syntaxes, 
>especially considering that:
>- although in some cases Internet media types owners may not need/want to 
>define a syntax, content owners may want to address fragments of content, 
>and have to define non-authoritative syntaxes,
>- in the future, it may be beneficial to establish common conventions for 
>addressing fragments consistently across multiple representations of a 
>content. Indeed at the moment, very few Internet media types have defined 
>a syntax for fragment identifiers.
>At the moment, both the RFC2396bis and the AWWW specify that:
>The semantics of a fragment identifier are defined by the set of
>    representations that might result from a retrieval action on the
>    primary resource.  The fragment's format and resolution is therefore
>    dependent on the media type [RFC2046] of a potentially retrieved
>    representation, even though such a retrieval is only performed if the
>    URI is dereferenced.
>This does not clearly state whether the use of a non-authoritative scheme 
>is valid or not. Another situation could happen if a non-authoritative 
>fragment syntax is widely used on the web for a particular representation 
>and later on an Internet media type owner registers a fragment syntax. 
>Both schemes could potentially coexist and be deployed assuming that the 
>syntaxes use a mechanism to help the processor identify which scheme 
>applies (for instance using a scheme name as for the Xpointer Framework).
>If the use of non-authoritative fragment identifier syntaxes in URIs is 
>allowed, although at the user's own risk, such URIs should be valid. 
>Therefore, I suggest that RFC2396bis clarifies whether a URI with 
>non-authoritative fragment identifier is still a valid URI or not.
>Best regards

Graham Klyne
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Received on Monday, 6 September 2004 16:23:19 UTC

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