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Review of RDF primer Revised Editor's Draft 21 July 2003

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Wed, 30 Jul 2003 18:27:23 +0100
To: w3c-rdfcore-wg@w3.org
Cc: Frank Manola <fmanola@mitre.org>, Eric Miller <em@w3.org>
Message-Id: <20030730182723.64003cb6.dave.beckett@bristol.ac.uk>

Review of

Last Modified: 07/25/03 15:34:11
400691 bytes

I reviewed the hilighted changes and did an HTML diff to check things.

Summary: it's good, publish(*)


(*)When the XML literal stuff get's decided


Detailed list

1 Introduction

P3 better maybe:
  ... a Person identified by the URI http://www.w3.org/People/EM/contact#me

last paragraph (new since LC)
  bullet list or bulleted list?

2. Making Statements About Resources

[paragraphs between figure 3 and 4)]

Paragraph "Using common ..."
"The RDF model only recognizes full URIrefs; it does not take
cognizance of particular ways of organizing or forming them."
 - sounds a bit high-powered :)

How about something like

"The RDF model only recognizes full URIrefs; it does not use look
inside URIrefs or use any knowledge of the structure of them."


[paragraphs after figure 4]


2.3 Structured Property Values and Blank Nodes

[paragraphs at end]

Maybe make the triple columns in those examples line up?

2.4 Typed Literals

[paragraphs after figure 7]

"An RDF typed literal is formed by pairing a plain literal with a URIref"

No it doesn't.  Since an RDF plain literal has a language component
which is (no longer) used here.  It just uses a string with a URIref.

[paragraphs after figure 9]

Paragraph "Unlike typical..."

Paragraph "RDF datatype concepts..." & bullets

Paragraph "Not all..."

Paragraph "Since the value..."
Not sure I like the [["first among equals" status in RDF.]] quote.
Who said that?  Has it any cultural problems? 

Paragraph "In general..."

Last Paragraph of 2.4
Do "proper" and "intended interpretation" have some special meaning?

There is a definition in RDF Semantics about this which might be
useful, where "bad" datatypes are not RDF literals, under a 
particular datatype entailment such as XSD-datatype-entailment.

I'm not sure how to easily translate that into simpler terms!
Maybe intended interpretation does work.  Your choice.

3.1 Basic Principles

Paragraph "(Note that..."

[after Example 2]

Paragraphs "Line 2..." to "Lines 4-6..."

[after Example 7]

Paragraph "In the rest of..."

Paragraph "Example 7 illustrates"... "For readability"

On entities - in this case only entities defined in the document,
i.e. in the "internal DTD subset" are likely to work.

You can use RDF/XML with a DTD and probably could do things
like declare entities there (or default attributes on elements etc. -
trickier since there is no DTD for RDF/XML) but we really
should encourage that.

Anyway, that's just information or advice.  Which might belong here.

3.2 Abbreviating and Organizing RDF URIrefs

Paragraph "These examples"

[Paragraphs after example 13]


Incidently Typed Nodes in the graph, known as Typed Node Elements in
the syntax.

4. Other RDF Capabilities

4.1 s/is/represents/ OK

[paragraphs before and after example 16]

Paragraph "Also, Example 14 and Example 15 ..."

Paragraph "As noted"
you mention well-formed here, but the caption on example 16 uses

4.2 RDF Collections

[paragraphs after example 16]

Seems ok updated for the implicit rdf:type rdf:List although
it may not be clear that this is RDFS entailment and not RDF.

  [RDF-SCHEMA] isn't linked to the reference.

Paragraph "RDF/XML provides..." & example

Paragraph "As noted in..."
There are lots of "quoted" phrases here, stands out.
Maybe you could rephrase longhand or just remove those quotes.

4.3 RDF Reification

Figure 17

It's a correct picture, however I guess you are stuck trying to show
that the same URI is used for a (green oval) as a resource object as
well as labeling an arrow for the predicate of the reified statement.

  "The subject of these reification triples is a URIref formed by
  concatenating the value of the rdf:ID attribute with the base URI
  of the document (given in the xml:base  declaration); that is, the
  triples have the same subject exproducts:triple12345 as in the
  previous examples."

Not correct.  It uses base URI + "#" +  value of the rdf:ID attribute.

4.4 More on Structured Values: rdf:value

Paragraph "Example 21 illustrates..."
[but I personally wouldn't recommend people use this style]

4.5 XML Literals

[I assume this section is still in a bit of flux]

The example22 ntriples misses out the leading and trailing whitespace
as well as the escapes for "en" (-> \"en\") and the escapes for
newlines -> \n in N-Triples.  

It should be:

ex:book12345 dc:title "\n       <span>\n         The <em>&lt;br /&gt;</em> Element Considered Harmful.\n       </span>\n     "^^rdf:XMLLiteral .

Paragraph "The value "
and lots more canonicalization, such as empty elements <foo/> -> <foo></foo>

Paragraph "This example"
There's another alternative, which is to use a non-XML typed literal;
ie a special datatype where the lexical form is separately defined.

5. Defining RDF Vocabularies: RDF Schema


5.1 Describing Classes

Paragraph "The meaning of this rdfs:subClassOf ..."

I see the use of an "RDF processor" and "RDF schema software"
The latter you define, but not the former.  If you could avoid
both that would be good.

Example 22 should have an xml:base, since it has rdf:IDs
[example 23 does].  Later after example23 you mention use
of xml:base so I expect you should change the rdf:IDs in
example 22 to be full URIs.

Example 24 - !  

Yes, it's correct but I'm sure people will get burnt with this kind
of thing.

Maybe you could explain the benefit (is there only one? :) of rdf:ID
- checking for duplicates in 1 document so that people can see when
it makes sense to use it.

5.2 Describing Properties


5.3 Interpreting RDF Schema Declarations

Paragraph "Another result"

5.4 Other Schema Information

Paragraph "As with"

5.5 Richer Schema Languages

bullet change OK

6.1 Dublin Core Metadata Initiative
Paragraph "Computer languages and file formats ..."



changes OK

6.3 XPackage

Example 37 includes this inside the rdf:

      <xpackage:location xlink:href="doc.html"/>

That is not RDF/XML, unless they meant this to be


In particular doc.html is not a URIref.

Ditto for example 38.

If however, these are not RDF/XML, this does not apply.

6.6 Gene Ontology Consortium

This syntax is bizarre, what is it doing in an RDF primer?

Please label Example 42 clearly with "not RDF/XML" in the caption
or give it style that shows it's not something people should try as
real RDF/XML.

7.1 RDF Semantics


Appendix A: More on Uniform Resource Identifiers (URIs)

Please label the state of this and other appendices in or near the
titld - this one is informative, but for the definitive use of URIs,
see RFC2396.

Paragraph "Carrying this point..."


Appendix B: More on the Extensible Markup Language (XML)

Ditto, "see XML 1.0 (Second edition)" for definitive info.

Paragraph "Finally, XML provides ...

Well, it is finally here, but XML provides lots of stuff and if you
include all the XML things that we do (XML, Namespaces, Infoset,
Base, Canonicalization, [schema]) then it's just a small intro, which
is the case.

spelling "Entitites"

I'd again avoid recommending or mentioning use of external DTDs.
Since RDF/XML uses the infoset that does not require validation,
use of external DTDs is possible but unlikely.

Example 46 is an internal DTD subset

You might take the blank lines out before and after <!DOCTYPE> - some
parsers are sensitive to that.
Received on Wednesday, 30 July 2003 14:02:21 EDT

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