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Re: 2001-09-07#5 Literals

From: Dan Connolly <connolly@w3.org>
Date: Wed, 26 Sep 2001 08:54:09 -0500
Message-ID: <3BB1DE01.AEEC15DB@w3.org>
To: "Jeremy Carroll (by way of Ralph R. Swick <swick@w3.org>)" <jjc@hplb.hpl.hp.com>
CC: w3c-rdfcore-wg@w3.org
"Jeremy Carroll (by way of Ralph R. Swick )" wrote:
> I am hoping that this text may be agreed upon on Friday.

Er... whoa! I'm having trouble following this thread...
I doubt I'll be prepared to decide on this by Friday.

I need direct implementation experience with whatever
proposal we come up with in order to be comfortable.
(test cases are really important for that, btw.)

In particular:


> [1]
> An RDF Literal is a Unicode string, optionally paired with a
> language tag (as defined in RFC3066).

What happened to the proposal that an RDF literal
is a (string, URI) pair?

As I've said, I think it's important to decide this
issue in the context of integration with XML schema
datatypes. But I can at least see how the (string, URI)
idea would work with XML schema datatypes.

> [1a]
> The Unicode String in an RDF Literal is normalized according
> to Unicode Normalization Form C [NFC, NFC-Corrigendum], using
> a framework of early uniform normalization.

Yikes! I haven't seen enough motivation to change the RDF 1.0
spec in that way. (maybe the motivation is there and I
just haven't read it.)

> [2]
> Future versions of RDF may migrate to a more general mechanism for
> literal representation in which the current representation would be
> embedded.

I'm not comfortable with that.

> One candidate is that an RDF literal would be a pair
> of a unicode string and a URI reference. The current literals would
> be embedded within this new representation using a well-known URI
> as a base for all language tag URIs.
> [3]
>    NOTE: The RDF Core Working Group has yet to consider whether
>    such an approach would be useful for integrating XML schema
>    datatyping with RDF.

I'm not comfortable with that either (as I've said).

> [4]
> When comparing two RDF Literals, their Unicode strings MUST be
> equal for the RDF Literals to compare as equal. If both Literals
> have language tags, these tags MUST be equal for the Literals to
> be considered equal. If two Literals are found with equal Unicode
> strings but only one has a language tag, the Literals SHOULD NOT
> be considered equal.


For the rest, I'd have to have my implementation-source-code
open in the other window to review it carefully. No
time for that just now. (I'm in another telcon :-( ).

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 26 September 2001 09:55:13 UTC

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