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Re: escaping % in RDF URI references

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Mon, 22 Sep 2003 16:12:04 +0300
To: pfps@research.bell-labs.com
Cc: www-rdf-comments@w3.org
Message-Id: <200309221612.04513.jjc@hpl.hp.com>


Hi Peter,

the changes referred to in this message are visible in the latest RDF Concepts 
editors draft:

http://www.w3.org/2001/sw/RDFCore/TR/WD-rdf-concepts-20030117/

(Which also includes the changes concerning NFC).

Thanks for your comments concerning RDF URI References.
http://lists.w3.org/Archives/Public/www-rdf-comments/2003JulSep/0316

As always your detailed criticism is valuable and has led to changes which the 
WG hope are improvements.

Dealing with the PS first:

[[
PS:  It appears to me that the translation in RDF Concepts is different
from the translation in Namespaces in XML 1.1.  In particular, RDF concepts
allows control characters whereas Namespaces in XML 1.1 does not.
]]

This was a mistake and has been rectified (see below for detail).

Concerning the main thrust,
[[
The wording in the ``Namespaces in XML 1.1'' document is *much*
preferable.  It lays out the intent, gives reasons why the intent cannot
be specified with just a pointer, provides a temporary solution, and
finally gives a way towards a permanent solution. 
]]

We asked the IRI editor for his opinion, he said:
http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Sep/0162
[[
As for the texts, I think both of them have advantages and
disadvantages. The best thing is to hurry up with the IRI
spec and remove these problems.
]]
after which the WG was not inclined to make a large editorial change. The 
current text has received a number of reviews already.

We however more positively considered your statement:
[[
It lays out the intent, gives reasons why the intent cannot
be specified with just a pointer, provides a temporary solution, and
finally gives a way towards a permanent solution.
]]
and felt that we should at least refer to the IRI draft. The RDF Core WG is 
however reluctant to try and predict the future,. so our wording was less 
assertive than that in XML Namespaces 1.1

So, we added:
- an informative reference to IRI draft
- the following note concerning the IRI draft
[[
Note: this section anticipates an RFC on Internationalized Resource 
Identifiers. Implementations may issue warnings concerning the use
of RDF URI References that do not conform with [IRI draft] or its 
successors.
]]
and made the following change concerning control characters:

***
Replace:
[[
A URI reference within an RDF graph (an RDF URI reference) is a Unicode string 
[UNICODE] that would produce a valid URI ...
]]

with
[[
A URI reference within an RDF graph (an RDF URI reference) is a Unicode string 
[UNICODE] that 
+ does not contain any control characters ( #x00 - #x1F, #x7F-#x9F)
+ and would produce a valid URI ...
]]
***

Please reply indicating whether these changes acceptably address your comment, 
with a copy to www-rdf-comments@w3.org.

Jeremy

PS The IRI draft 04 diverges from the XML Namespaces text, it contains the 
following note:

[[
   Note: Earlier drafts of this specification allowed the space
   character and various delimiters in IRIs and IRI references.  The
   full list of these characters was: "<", ">", '"', Space, "{", "}",
   "|", "\", "^", and "`", i.e.  all printable characters in US-ASCII
   that are not allowed in URIs.  For backwards compatibility,
   implementations MAY also include these characters in step 3) above.
   If such characters are found but are not converted, then the
   conversion SHOULD fail.  Please note that the number sign ("#"), the
   percent sign ("%"), and the square bracket characters ("[", "]") are
   not part of the above list, and MUST not be converted.  Protocols and
   formats that have used earlier definitions of IRIs including these
   characters MAY require unescaping of these characters as a
   preprocessing step to extract the actual IRI from a given field.
   Such preprocessing MAY also be used by applications allowing the user
   to enter an IRI.
]]
Received on Monday, 22 September 2003 10:12:16 GMT

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