investigate a datatype for handling date-time values

[djhaynes]

Given the variety of date-time value formats across platforms, we should investigate the possibility of a datatype for date-time values. Having such a datatype could help consolidate the use of date-time values in OVAL for both tool developers and content authors.

The W3C specification for dateTime values may serve as a good option for this.

http://www.w3.org/TR/xmlschema-2/#dateTime