OMG Systems Modeling Language

This should support the ability to define a state machine of
a structural element, with finite states that enable actions
(i.e., functions) and constraints. In addition, this should
support the ability to specify the functions performed by a
component, and the applicable constraints, without
specifying the finite state that enables them.

The representation should allow more than one structural
element to perform a single function, such as when two
people carry a load. This is analogous to a reference
interaction in a SysML v1 sequence diagram that spans
multiple lifelines and displays the participating lifelines.
The reference interaction refers to another sequence
diagram.