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Documented MIME-type dependency of fragment identifiers

From: Graham Klyne <GK@NineByNine.org>
Date: Fri, 05 Jul 2002 16:49:26 +0100
Message-Id: <>
To: RDF core WG <w3c-rdfcore-wg@w3.org>

During a recent informal telephone discussion, I was asked to post 
references to documentation indicating that the interpretation of fragment 
identifiers on URIs, in normal web use, is considered to be dependent on 
the MIME content-type of the resource representation obtained.

This is what I have:

RFC2396, section 4.1
4.1. Fragment Identifier

    When a URI reference is used to perform a retrieval action on the
    identified resource, the optional fragment identifier, separated from
    the URI by a crosshatch ("#") character, consists of additional
    reference information to be interpreted by the user agent after the
    retrieval action has been successfully completed.  As such, it is not
    part of a URI, but is often used in conjunction with a URI.

       fragment      = *uric

    The semantics of a fragment identifier is a property of the data
    resulting from a retrieval action, regardless of the type of URI used
    in the reference.  Therefore, the format and interpretation of
    fragment identifiers is dependent on the media type [RFC2046] of the
    retrieval result.  The character restrictions described in Section 2
    for URI also apply to the fragment in a URI-reference.  Individual
    media types may define additional restrictions or structure within
    the fragment for specifying different types of "partial views" that
    can be identified within that media type.

    A fragment identifier is only meaningful when a URI reference is
    intended for retrieval and the result of that retrieval is a document
    for which the identified fragment is consistently defined.

TimBL's design issues series:

Also, I came across this in Roy Fielding's thesis:
REST accomplishes this by defining a resource to be the semantics of what 
the author intends to identify ...

I'll also remind you of the words I have suggested for reconciling RDF's 
use of URIrefs (with fragment identifiers) with this current Web usage:

Finally, I note that the current TAG discussion of this issue is taking 
place in a slightly different context, namely the use of HTTP URIs:


Graham Klyne
Received on Friday, 5 July 2002 11:34:24 UTC

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