Tapestry traditionally has namespaced all ids generated during an Ajax partial page render (the result of clicking a link, or submitting a form, that updates a Zone on the client). The namespacing is the injection of a arbitrary string (a nanosecond timestamp, in hex) into the middle of all ids. This ensures no name collisions on the client ... but it breaks other features, such as rendering of validation errors for a Form nested inside the Zone.
By disabling this feature, and allocating ids exactly the way they would be during a traditional full-page render, some features (such as rendering validation errors) can be restored ... for simple pages!
This feature should only be used as a last resort, since it can have unexpected consequences.