pDocumentTemplate has some trouble with the "this" attribute. Since

pDocumentTemplate compatibility is not vital, this solution
works well enough.

lib/python/App/special_dtml.py

@@ -193,7 +193,7 @@ class DTMLFile(Bindings, Explicit, ClassicHTMLFile):
             # Someone called us.
             push(cns)
             ns.level = cns.level + 1
-            ns.this = cns.this
+            ns.this = getattr(cns, 'this', None)
             # Get their bindings.  Copy the request reference
             # forward, and include older keyword arguments in the
             # current 'keyword_args' binding.