[Zope] Accsessing the folder above

Hi! I'm trying to display all folders in the folder above my product(derived from a folder) in a tree. It must be something like this: <dtml-tree branches_expr="Subfolder.objectValues(['Folder'])"> ... </dtml-tree> The problem is, that this doesn't work. I search something for "Subfolder", which includes the folder above. It works with the name of the Folder, but I want to use the product in every folder without changing it every time. Thanks Sebastian