Diego Rodrigo Neufert writes:

Why there isnt a dtml-while function in Zope? How to implement it with dtml? how to do a simple while x != y in dtml? Because the Zope developers feared infinite loops created by dumb users or malicious hackers in "through the web" content. For the same reason, "_.range" has been cripled and the module "re" is not exposed.

Dieter