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non-authoritative syntaxes for fragment identifiers

From: Myriam Amielh <myriam.amielh@cisra.canon.com.au>
Date: Fri, 03 Sep 2004 13:31:30 +1000
Message-ID: <4137E592.8070007@cisra.canon.com.au>
To: public-webarch-comments@w3.org

Hello,

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 two observations for the Last Call on 
AWWW:

1) Paragraph 4 of clause 3.3 specifies:

As with any URI, use of a fragment identifier component does not imply 
that a retrieval action will take place. A URI with a fragment 
identifier may be used to refer to the secondary resource without any 
implication that the primary resource is accessible or will ever be 
accessed. One may compare URIs with fragment identifiers without a 
retrieval action. *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*.

In the last sentence (between **), up to the semi-column, no hypothesis 
was made whether the fragment syntax is based on an authoritative scheme 
or not (so for instance, we may very well be talking about the 
authoritative svg fragment identifier #svgView()). Then, the statement 
"such interpretations are not authoritative" may apply both to 
authoritative or non authoritative syntaxes, and that may be confusing.

I wonder whether the intention was more something like:

*Parties that draw conclusions about the interpretation of a fragment 
identifier based solely on a syntactic analysis of all or part of a URI, 
*and not on a registered syntax*, do so at their own risk; such 
interpretations are not authoritative because they are not licensed by 
specification.*

2) 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 AWWW clarifies whether a URI with 
non-authoritative fragment identifier is still a valid URI or not.

Best regards
Myriam
Received on Friday, 3 September 2004 03:33:17 UTC

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