Representing domain and/or range in OWL

Hello,

I can represent the domain and/or range values of a Property P as follows:

<owl:ObjectProperty rdf:ID="P">
 <rdfs:domain>
                <owl:Class>
                <owl:unionOf rdf:parseType="Collection">
                    <owl:Class rdf:about="#A"/>
                    <owl:Class rdf:about="#B"/>
                    <owl:Class rdf:about="#C"/>
                </owl:unionOf>
            </owl:Class>
    </rdfs:domain>
</owl: ObjectProperty>

Where Classes A , B and C have been defined elsewhere in the file. I 
create an instance of A, B or C and apply the property P to the instance.

< A rdf : ID ="abc">
    <P>#xyz</P>
</A>

After this when I validate the Ontology, I get the following warning for 
property P:

 Use of this property implies that subject is of type 
anon:ee4648:f5d1c5f1e1:-7fb0.  (Subject is declared type 
[http://www.temp/temp.owl#A])

I am not sure if  anon:ee4648:f5d1c5f1e1:-7fb0 has been generated when 
the about attribute for the class was parsed. Is this suppose to be 
treated as a serious error and is this representation of domain wrong? I 
am confused .

Any help well apppreciated.

Thanks,

Monika

p.s: I am using the bbn owl validator.
-- 
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Monika Solanki
De Montfort University
Software Technology Research Laboratory
Hawthorn building, H00.18
The Gateway.
Leicester LE1 9BH, UK

phone: +44 (0)116 250 6170 intern: 6170
email: monika@dmu.ac.uk <mailto:monika@dmu.ac.uk>
web: http://www.cse.dmu.ac.uk/~monika/ 
<http://www.cse.dmu.ac.uk/%7Emonika/>
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