The following datatypes are RECOMMENDED for use with OWL: xsd:string, xsd:boolean, xsd:decimal, xsd:float, xsd:double, xsd:dateTime, xsd:time, xsd:date, xsd:gYearMonth, xsd:gYear, xsd:gMonthDay, xsd:gDay, xsd:gMonth, xsd:hexBinary, xsd:base64Binary, xsd:anyURI, xsd:normalizedString, xsd:token, xsd:language, xsd:NMTOKEN, xsd:Name, xsd:NCName, xsd:integer, xsd:nonPositiveInteger, xsd:negativeInteger, xsd:long, xsd:int, xsd:short, xsd:byte, xsd:nonNegativeInteger, xsd:unsignedLong, xsd:unsignedInt, xsd:unsignedShort, xsd:unsignedByte and xsd:positiveInteger.

Other datatypes, including the other built-in XML Schema datatypes MAY be used.

NOTE: specific considerations with the other built-in XML Schema datatypes are:

xsd:duration,

In this version of XML Schema no equality function is defined for xsd:duration. This may give surprising results when combined with OWL cardinality constraints. Later revisions of XML Schema datatypes are expected to provide such a function, in which case the revised duration datatype would be fully appropriate for use with OWL.

xsd:QName,

xsd:ENTITY,

These datatypes require an enclosing XML document context, which may not be available in a specific application scenario for an OWL ontology.

xsd:NOTATION,

This datatype is intended for use as a base type for user defined datatypes.

xsd:ID,

xsd:IDREF,

The use of xsd:NCName is RECOMMENDED in OWL.

xsd:IDREFS,

xsd:ENTITIES,

xsd:NMTOKENS,

List valued datatypes are OPTIONAL in OWL.