[Zope] Formatted date anomaly ...

Mon, 7 Feb 2000 23:52:17 +1100 (EST)

Here's a strange one.  I have a property StartDate (type date)
set to "01/01/2000".  Can someone please explain why the DTML
snippet:
     <dtml-var StartDate> <dtml-var StartDate fmt="%Y"> 
renders as:
     2000/01/01 1999

(More info on Zope formatting of dates and times can be found in
the HowTo:
    http://www.zope.org/Members/AlexR/CustomDateFormats)

Cheers,
Darran.