The extent by which application objects (such as forms, tables and data entities) are extensible will evolve with each release. Currently, we can add data sources, ranges, relations, field groups, and table maps to data entities. We cannot add new methods or change existing ones, as this would result in no practical difference to an over-layer (except it could be worse, as no tooling would exist for conflict management). Instead, we would subscribe to the many event delegates.