For your information:

ROOT has an automatic schema evolution implemented. That means, that all trees 
can be filled into a class from a file, even if the class definition has 
changed (take a look at the input/output section in the root manual).
This works also in the rome environment. All you have to do is to increment the 
version number of a folder, every time you change the folder.

This works for adding, removeing or changing fields. However, if you remove or 
change a field you will have to change your user code, because the Get and Set 
methods will be changed or removed too. So you better think twice about the 
contents of a folder.

Matthias