- Metadata – Various annotation properties used to document the entire ontology suite.
- Core – Collects the top-level classes and properties that span over or are reused within multiple REC modules. Imports the Metadata module, and is imported by all other specific child modules.
- Agents – Basic types of agents (people, organizations, groups), structurally aligned with FOAF.
- Building – Different types of building components and rooms.
- Device – Device types (sensors and actuators), device configuration, device actuation, etc.
- Lease – Contracts, leasable premises, types of premises, etc.
- REC Full – Imports all REC modules, providing the fullest possible expressivity.