Standard file format for describing hierarchical (nested) machines of final state?

I need to describe a hierarchical end state machine in a standard and portable format. Is there a generally accepted and supported file format that I should use?

• I see that the DAT Graphviz language supports subgraphs that can be referenced by oriented edges. (Although rendering clustered clusters using Graphviz is a small problem .) Interpreting a text label on a common directed edge as a transition / criterion event seems like light semantic stretching, but is not unusable.

• I see that UML Statechart supports hierarchically nested states . However, the accepted answer to this question implies that the description of statechart in XMI cannot actually be compatible with tools that nominally support UML.

• I see the W3C SCXML Standard . However, this is still a working draft (and it lasts almost 7 years), and I'm not sure if any tool supports this format (except for conversion ).

Is there a more acceptable alternative than one of the above? Should I use one or the other of the above?

One example of portability is that I would like the chart to be read and used by an HSM simulator such as Matlab Stateflow .