[Zope] dtml methods and properties

As a DTML method is said to work with the properties of the object it is called at: DTML method "m": <dtml-var bobobase_modification_time> <root folder of site>/m displays the date/time when the last change happened to any file in the root folder <root folder>/m/m displays last change date/time of method m Why does the method not display it's modification time on the first occasion? Or: why does it not give the folder's modification time on the second occasion? - Willem