[Zope] how do I show the contents of a sub folder using the dtml-in tag?

I have a folder called alpha containing a folder subalpha. In a DTML document within alpha I want to list the contents of subalpha using objectValues. Basically I would like to use something like <dtml-in "PARENTS[0].objectValues(['Folder'])">, but going DOWN instead of UP... I haven't found anything in the various newsgroups (except for <dtml-in "subalpha.objectValues(['Folder'])">, which does not work...). Thanks in advance for any help.