techblog 

One limitation I found when using Web Ontology Language (OWL) was that it does not support customised datatypes. I realise that the
main purpose of OWL is to recording how data relates to real world objects, but allowing authors to reference XML Schema to define OWL-related
datatypes, while keeping an OWL document in valid DL form would be most useful.

Some work has been undertaken in addressing this (see Working Group Note “XML Schema Datatypes
in RDF and OWL” - specifically using the id attribute), adding an ID to the XML Schema. then referencing it in the OWL Document:

<owl:DatatypeProperty rdf:ID="domainNameValue">
<rdfs:domain rdf:resource="#domainName"/>
<rdfs:range rdf:resource=
"http://xml.nominet.org.uk/schema/datatypes#domainName"/>
</owl:DatatypeProperty>

..but using customised datatypes through this method turns documents into OWL Full, which is not ideal. Due to its syntactic freedom,
it is unlikely that future reasoning software will be able to support complete reasoning for OWL Full.

Interestingly enough. further to the W3C reccomendation, a possible extension
OWL-Eu has been suggested to overcome this, but as far as I know this datatype issue hasn’t yet been resolved within the W3C reccomendation,
and until this point reasoning tools will not likely support this.

Real world Semantic Web tools will only support OWL DL due to the limitations/complexities of OWL Lite/Full,
so unless users can create OWL DL documents using customised datatypes, the takeup of OWL will probably be slow.