When should you use rdf: ID instead of rdf: about?

Question

I go through the bottom of the owl document, we have:

<!-- Object Properties -->
<owl:ObjectProperty rdf:about="#contains"/>
<owl:ObjectProperty rdf:about="#datePublished"/>
<owl:ObjectProperty rdf:about="#hasGenre"/>
<owl:ObjectProperty rdf:about="#hasGrade"/>
<owl:ObjectProperty rdf:about="#hasName"/>
<owl:ObjectProperty rdf:about="#hasSize"/>
<owl:ObjectProperty rdf:about="#hasType"/>
<owl:ObjectProperty rdf:about="#isTitled"/>
<owl:ObjectProperty rdf:about="#publishedBy"/>
<owl:ObjectProperty rdf:about="#timePublished"/>
<owl:ObjectProperty rdf:about="#writtenBy"/> 
<owl:ObjectProperty rdf:ID="isReserved">
<rdfs:domain rdf:resource="#Book"/>
<rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
>A reservation has been made by a person for a book.</rdfs:comment>
</owl:ObjectProperty>
<owl:ObjectProperty rdf:ID="isNotReserved">
<rdfs:domain rdf:resource="#Book"/>
<rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
>The given book is available in the library.</rdfs:comment>
</owl:ObjectProperty>
</rdf:RDF>

I just can not understand why the author prefers to use this ontology rdf:IDin the last two owl:ObjectProperty( isReservedand isNotReserved) instead of simply using rdf:aboutthe other?

ps : I fully read the part of RDF / XML that indicates the use of xml:baseand rdf:IDand checked in the answer here , I just need additional clarification in the context of the ontology defined in the above view.

Quote from RDF / XML Specification :

rdf: ID node ( , ) rdf: about IRI #, rdf: ID. , rdf: ID = "", : = "# ". rdf: ID , xml: base ( , ), IRI.

Answer 1

, rdf: ID : ObjectProperty (isReserved isNotReserved) , rdf: ?

. RDF/XML , . Rdf: ID rdf: RDF; XML- RDF RDF/XML. RDF/XML, RDF RDF/XML . ., , OWL XPath Java? .

, books.owl Jena XML. books.owl . rdf: ID, RDF. RDF , .. . , rdf: ID,

<owl:ObjectProperty rdf:about="http://127.0.0.1:3001/ontology/books.owl#isNotReserved">
  <rdfs:domain rdf:resource="http://127.0.0.1:3001/ontology/books.owl#Book"/>
  <rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
  >The given book is available in the library.</rdfs:comment>
</owl:ObjectProperty>

, , rdf: rdf: ID, - . - RDF/XML 1.1, , & sect; 2.14 URI: rdf: ID xml: base.

, , , , , . Gist Turtle, books.ttl. Turtle , rdf: ID rdf: about. Turtle :

:isNotReserved a owl:ObjectProperty ;
    rdfs:comment "The given book is available in the library."^^<http://www.w3.org/2001/XMLSchema#string> ;
    rdfs:domain :Book .