[Zope] date question

hi there, how to deal with the dayOfYear in dtml-if ? <dtml-if "_.DateTime() > 70"> <dtml-var "_.DateTime()" fmt=dayOfYear> > 70 </dtml-if> i would like to change the dtml-if so that it would be able to distinguish the two dayOfYear-integer correct. the source below isn´t correct but <dtml-if "_.DateTime() fmt=dayOfYear > 70"> doesn´t work. thanks,