Data Model: Date and Time

Hi,

I cannot agree with the separation of 'Date ' and 'Time of Day'!
'Time of Day' is left truncated and only useful for
the specification of a recurring event. XML-Schema
is much clearer about that and named it 'recurringInstant'.
It's very easy to incoporate the time part into the
'Date' datatype: a simple merge of the values of the facet
'precision'.
Moreover, the separation of the types is difficult to handle
if you use they in expressions like 'above' or 'below'.

I can advice an excellent paper about time and granularity
(precision):

 Efficiently Supporting Temporal Granularities 
 Curtis E. Dyreson, William S. Evans, Hong Lin, Richard T. Snodgrass 
 September 3, 1998 
 TR-31 
 A TIMECENTER Technical Report 
 URL: <http://www.cs.auc.dk/research/DBS/tdb/TimeCenter/> 


Steffen Goeldner