An approach to xsd:dateTime

As I read the XML Schema 1.1 description of dateTime [1], the primary
problem it presents as a datatype is that timezone is optional.  If OWL
were to require the timezone property, all values map to a single point
on a discrete number line (see [2]), making implementation equivalent to
implementation of xsd:integer.

Do others find this to be accurate?  A reasonable path forward?
-- 
Mike Smith

Clark & Parsia

[1] http://www.w3.org/TR/xmlschema11-2/#dateTime
[2] http://www.w3.org/TR/xmlschema11-2/#vp-dt-timeOnTimeline