An element can exist in exactly one model in a layer. The same element can exist
in a customized version in a model in a higher layer. New models are easy to
create in the MorphX IDE and are applied when modifying or adding objects in
the AOT. Models can be exported, installed, or uninstalled from the model store.
Models are identified by a name and a publisher, and have a set of properties that
can be changed, including a version number.