RE: SubClassOf vs Child Element

Hello Jie,
 
In fact, you cannot do what you did in your second example. Because this
would
mean that you may have an 'rdfs:Property' property on a 'rdfs:Property'-
typed node.
 
'rdfs:Property' is a class whereas 'rdfs:subPropertyOf', 'rdfs:domain' and
'rdfs:range'
are properties. In RDF, the child element structure does have a particular
semantic.
You can be in either of this two cases:  
    - you are in an element that represents an instance
            and so what you put in is the elements for its properties  
    - you are in an element that represents a property for an instance
            and so what you put in is the element (or string) for its
instance value
 
So when you write:
 
<rdf:RDF  
                xmlns:rdf="http://www.w3.org/..."  
                xmlns:myNS="http://www.example.com/MyVocabulary"
>
    <rdf:Description rdf:ID="toto">
        <myNS:myPropertyName>A value</myNS:myPropertyName>
    </rdf:Description>
</rdf:RDF>
 
You just tell this triple:
 
(#toto, http://www.example.com/MyVocabulary#myPropertyName,
<http://www.example.com/MyVocabulary#myPropertyName>  "A value")
 
which means in english, "#toto has 'A value' for myPropertyName".