In a rigiedit operation, you may be required to specify a particular node type (through the Node Type palette). Most node types are domain-specific; following is a description of the domain-independent node types that arise when producing a subsystem containment hierarchy.
Nodes of this type are subsystems that contain other nodes and are formed by collapsing these other nodes.
The Collapse node type is automatically added if not present in the loaded domain model.
Technical: Multiple types of subsystem nodes are supported through RCL commands. Essentially, any node type can become the current subsystem node type. By default, the current subsystem node type is the one named Collapse.