Web Ontology Language: OWL 15 Note that owl: distinctMembers can only be used in combination with Owl: AllDifferent Datatypes Although XML Schema provides a mechanism to construct user-defined datatypes(e.g. the datatype of adultAge as all integers greater than 18, or the datatype of all strings starting with a number ), such derived datatypes cannot be used in OWL. In fact, not even all of of the many the built-in XML Schema datatypes can be used in OWL. The OWL reference document list ll the XML Schema datatypes that can be used, but these include the most frequently used types such as string, integer, boolean, time and date Versioning information We have already seen the owl prior Version statement as part of the header information to indicate earlier versions of the current ontology. This informa- tion has not formal model-theoretic semantics but can be exploited by humans readers and programs alike for the purposes of ontology management Besides owl: prior Version, OWL has three more statements to indicate fur- ther informal versioning information. None of these carry any formal meaning An owl: versionInf statement generally contains a string giving infor mation about the current version, for example RCS/CVS keywords An owl: backwardCompatibleWith statement contains a reference to an- other ontology. This identifies the specified ontology as a prior version of the containing ontology, and further indicates that it is backward com- patible with it. In particular, this indicates that all identifiers from the previous version have the same intended interpretations in the new ver sion. Thus, it is a hint to document authors that they can safely change their documents to commit to the new version(by simply updating names- pace declarations and owl: imports statements to refer to the URL of the new version An owl: incompatibleWith on the other hand indicates that the ing ontology is a later version of the referenced ontology, but is no ward compatible with it. Essentially, this is for use by ontology who want to be explicit that documents cannot upgrade to use version without checking whether changes are required Layering of OWL Now that we have discussed all the language constructors of OWL, we can completely specify which features of the language can be used in which sub- language(OWL Full, DL and Lite)Web Ontology Language: OWL 15 Note that owl:distinctMembers can only be used in combination with owl:AllDifferent. Datatypes Although XML Schema provides a mechanism to construct user-defined datatypes (e.g. the datatype of adultAge as all integers greater than 18, or the datatype of all strings starting with a number), such derived datatypes cannot be used in OWL. In fact, not even all of of the many the built-in XML Schema datatypes can be used in OWL. The OWL reference document lists all the XML Schema datatypes that can be used, but these include the most frequently used types such as string, integer, boolean, time and date. Versioning information We have already seen the owl:priorVersion statement as part of the header information to indicate earlier versions of the current ontology. This informa￾tion has not formal model-theoretic semantics but can be exploited by humans readers and programs alike for the purposes of ontology management. Besides owl:priorVersion, OWL has three more statements to indicate fur￾ther informal versioning information. None of these carry any formal meaning. • An owl:versionInfostatement generally contains a string giving infor￾mation about the current version, for example RCS/CVS keywords. • An owl:backwardCompatibleWith statement contains a reference to an￾other ontology. This identifies the specified ontology as a prior version of the containing ontology, and further indicates that it is backward com￾patible with it. In particular, this indicates that all identifiers from the previous version have the same intended interpretations in the new ver￾sion. Thus, it is a hint to document authors that they can safely change their documents to commit to the new version (by simply updating names￾pace declarations and owl:imports statements to refer to the URL of the new version). • An owl:incompatibleWith on the other hand indicates that the contain￾ing ontology is a later version of the referenced ontology, but is not back￾ward compatible with it. Essentially, this is for use by ontology authors who want to be explicit that documents cannot upgrade to use the new version without checking whether changes are required. Layering of OWL Now that we have discussed all the language constructors of OWL, we can completely specify which features of the language can be used in which sub￾language (OWL Full, DL and Lite):