Variablle abstraction possible in Simulink and/or Matlab?

Is there a way in Simulink (perferably - or in Matlab) to create an abstract data type? For example, in a Simulink state chart I want to have the arrival of a position change event trigger a transition to another state. I want the 'position' variable to be comprised of coordinates in 3-space. Can I define a 'position' variable to be composed of the following:

• position.x - 16 bit integer
• position.y - 32 bit integer
• position.z - 32 bit floating pt.

At some level in the state chart hierarchy, simply refer to 'position'?

Thanks

-John