[Zope] Inserting foldernames into propertysheet 'selection' dropdown

[Gary Duke Speer]

Happy Friday -
I'm looking for syntax to properly pass folder names as a list to a
propertysheet selection property.

Every syntax I try gets:
  Error Type:  In Error
  Error Value:  Strings are not allowed as input to the in tag.

The propertysheet has property 'selectfolder' of type 'selection' set to
look to a method 'getfolders' for the list of options.

The documentation says this property type wants either a list or tokens.

One example:
A dtml method named 'getfolders' contains
<dtml-in "objectValues(['Folder'])><dtml-var id> </dtml-in>
And renders space separated tokens.

My question is how to change this to produce a list in a format that the
property will accept.
Thank you for any guidance!
Duke