About Rigid Product Structures

A rigid product structure involves subproducts that are not repositionable. This is not the case for positional mechanical references, also referred to as PMRs.

For more information, see About Flexible Product Structures

You can build more simple mechanisms based on engineering connections with rigid product structures as well as assemble submechanisms.

See Also
Defining a Mechanism
Defining an Assembly of Mechanisms

When you create a mechanism representation, all of the engineering connections under the root product are available to use as joints in the mechanism.

Submechanisms are ignored by default if a macro mechanism (green frame in the figure) is simulated on the main product. If the macro mechanism assembles submechanisms, and if you run a simulation on the macro mechanism, then the submechanisms move along. The subproduct (red frame in the figure) remains rigid for all subsequent assembly and kinematics applications.