UPDATE: Please download this product from IssueTrackerProduct.com from now on.
CheckoutableTemplates allows you to make exceptions to DTMLFile and PageTemplateFile attributes of a Python product. This is highly usable if you have an instance of a Python product class, and you want to change some little thing in one of its templates.
In Zope, it is NOT possible to subclass an template attribute from withing the ZMI. Having templates as attributes in a Python product class is useful because when you roll out a new version, it's easy to include your changes. It's also useful in that you can make the Zope object instance very simple.
The advantage about only having templates instanciated inside the class instance in Zope is that you can make changes to the look and feel of one and only one instance.
Screenshot 1 and Screenshot 2 of how your showCheckoutableTemplates can look like.
showCheckoutableTemplates