Environment model is that of present day social 3d environments, online games and first person shooters:

1. Environment is divided into simulation nodes which are simulated by separate servers (load balancing).
2. Map. Slowly changing part of the environment. 3d engine handles this part as a static "level" map. Each simulation provides its own map. Maps need to be compatible at connection points to other simulations. Each map could be defined as a Collada model.
3. Dynamic objects. Dynamic objects are all the objects in the environment which can move or interact. Dynamic objects are presented by Collada models and can have animation state. All state changes inside one dynamic object is presented as animation to the user. As a thumb of rule all objects are directly connected to root coordinate space from the protocol perspective. Simulation may internally use nested coordinate spaces in other words transformation hierarcies for simulating attachments and forces between objects. When the object movement is presented in observation messages all the values are given in root coordinate space. Migrations may need to support nesting to inform target simulation about relations between objects that are migrating between simulations.
4. Avatar is the dynamic object representing users chosen virtual identity in the environment.