When creating new Zope page templates or modifying existing ones, the ZMI uses a built-in syntax checker that ensures that templates with errors are not published. When you press the button to save template additions or changes, the ZMI displays the error type and location (using line numbers ) and does not save the file until those items are fixed. However, the nature of these error messages might require further explanation if you are not well versed in the Zope Template Language. Keep handy Appendixes A and C of The Zope Book : "DTML Reference" and "Zope Page Templates Reference," respectively. The URL to the current Zope Book is http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/. After your templates have been published, if you decide that you don't like your changes, the Undo tab is only one click away, as always.