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Re: take 2: primer text for parseType="Literal"

From: Graham Klyne <gk@ninebynine.org>
Date: Fri, 25 Jul 2003 10:03:44 +0100
Message-Id: <5.1.0.14.2.20030725095759.02b8ba78@127.0.0.1>
To: Frank Manola <fmanola@mitre.org>
Cc: rdf core <w3c-rdfcore-wg@w3.org>

This looks good to me.  One tiny nit and one small comment:

Nit: The use of "third" in "using a third value of the rdf:parseType 
attribute" seemed a little odd to me.  Maybe just:  'using the attribute 
rdf:parseType="literal"'?

Comment:  it might help to underscore somehow that using 
rdf:parseType="literal" doesn't require that the data contain markup.  This 
is implicit and clear to one who has followed this discussion, but I'm not 
sure how clear that would be to someone coming fresh to this text.

For example, may the sentence:
[[
The value of the property is a typed literal, whose datatype, 
rdf:XMLLiteral, is defined in [RDF-CONCEPTS] specifically to represent 
fragments of XML.
]]

might be:

[[
The value of the property is a typed literal, whose datatype, 
rdf:XMLLiteral, is defined in [RDF-CONCEPTS] specifically to represent 
fragments of XML, including character sequences that may or may not include 
XML markup.
]]

#g
--

At 15:05 24/07/03 -0400, Frank Manola wrote:

>Based on Brian's last "take", I propose to put the following text in the 
>Primer for parseType="Literal".  The typed literal given for the value of 
><dc:title> in the triple is that produced by the RDF Validation Service, 
>but someone may want to check this further anyway.
>
>4.5  XML Literals
>
>Sometimes the value of a property needs to be a fragment of XML, or text 
>that might contain XML markup.  For example, a publisher might maintain 
>RDF metadata that includes the titles of books and articles.  While such 
>titles are often just simple strings of characters, this is not always the 
>case.  For instance, the titles of books on mathematics may contain 
>mathematical formulas that could be represented using MathML [MATHML]. 
>Titles might also include markup for other reasons, such as for Ruby 
>annotations [RUBY], or for bidirectional rendering or special glyph 
>variants (see, e.g., [CHARMOD]).
>
>RDF/XML provides a special notation to make it easy to write literals of 
>this kind.  This is done using a third value of the rdf:parseType 
>attribute.  Giving an element the attribute rdf:parseType="Literal" 
>indicates that the contents of the element are to be interpreted as an XML 
>fragment.  Example 22 illustrates the use of rdf:parseType="Literal":
>
><?xml version="1.0"?>
><rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>    xmlns:dc="http://purl.org/dc/elements/1.1/"
>    xml:base="http://www.example.com/books">
>
>   <rdf:Description rdf:ID="book12345">
>     <dc:title rdf:parseType="Literal">
>        <span xml:lang="en">
>          The <em>&lt;br /&gt;</em> Element Considered Harmful.
>        </span>
>     </dc:title>
>   </rdf:Description>
>
></rdf:RDF>
>
>The RDF/XML in Example 22 describes a graph containing one triple:
>
>ex:book12345 <dc:title> "&lt;span xml:lang="en"&gt; The &lt;em&gt;&lt;br 
>/&gt;&lt;/em&gt; Element Considered Harmful. &lt;/span&gt;"^^rdf:XMLLiteral .
>
>The rdf:parseType="Literal" attribute in the RDF/XML indicates that all 
>the XML within the <dc:title> element is an XML fragment that is the value 
>of the dc:title property.
>
>The value of the property is a typed literal, whose datatype, 
>rdf:XMLLiteral, is defined in [RDF-CONCEPTS] specifically to represent 
>fragments of XML.  The XML fragment is canonicalized according to the XML 
>Exclusive Canonicalization recommendation [XML-XC14N].  This causes 
>declarations of used namespaces to be added to the fragment, the escaping 
>of reserved characters such as '<', '>' and '&', and possibly, the 
>re-ordering of attributes.  Contextual attributes, such as xml:lang and 
>xml:base are not inherited from the RDF/XML document, and, if required, 
>must, as shown in the example, be explicitly specified in the XML fragment.
>
>This example illustrates that care must be taken designing RDF data.  It 
>might appear at first glance that titles are simple strings best 
>represented as plain literals, and only later might it be discovered that 
>some titles contain markup.  In cases where the value of a property may
>sometimes contain markup and sometimes not, either rdf:parseType="Literal" 
>should be used throughout, or software must handle both plain literals and 
>rdf:XMLLiterals as values of this property.
>
>@@Informational References to be added:
>
>[RUBY] Ruby Annotations, Sawicki, M., Suignard, M., Ishikawa, M., Durst, 
>M., Texin, T., World Wide Web Consortium, 31 May 2001.  This version is 
>http://www.w3.org/TR/2001/REC-ruby-20010531/.  The latest version is 
>http://www.w3.org/TR/ruby/.
>
>[XML-XC14N] @@use citation in Syntax
>
>[CHARMOD]  @@use citation in Syntax
>
>[MATHML] Mathematical Markup Language (MathML) Version 2.0, Carlisle, D., 
>Ion, P., Miner, R., Poppelier, N. (Editors); Ausbrooks, R., Buswell, S., 
>Dalmas, S., Devitt, S., Diaz, A., Hunter, R., Smith, B., Soiffer, N., 
>Sutor, R., Watt, S. (Principal Authors), World Wide Web Consortium, 21 
>February 2001.  This version is 
>http://www.w3.org/TR/2001/REC-MathML2-20010221.  The latest version is 
>http://www.w3.org/TR/MathML2.
>
>
>
>
>--
>Frank Manola                   The MITRE Corporation
>202 Burlington Road, MS A345   Bedford, MA 01730-1420
>mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875

-------------------
Graham Klyne
<GK@NineByNine.org>
PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E
Received on Friday, 25 July 2003 05:12:37 EDT

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