In reply to Chandan Mathur:
Chandon,
Apologies.
Re: UML v2.5.1, section 14.2.2 (not being argumentative) as I read the Abstract Specification of a Transition, a Transition may have an optional property named "guard" which is of type Constraint, which is further constrained to a single Constraint specification if present (multiplicity = 0..1). I make no claim to being a UML expert and may interpretation is based solely on my independent study of the language. I may be wrong. This is my understanding and I do not intend to argue the point, but I am willing to correct my understanding with inout from an expert.
I played around with CSM 19.4 this morning trying both OCL for the Guard and an "Opaque Expression". While I still believe that the Constraint model element is appropriate, I concur the behavior of the tool may be a suboptimal solution.
Another approach: Consider specifying your complex Guard expression in the form of an Opaque Expression. In my experimentation, I created a separate package containing the named opaque expression ( I named the expression as the hyperlinking dialog lists model elements by their name). Then from the specification of the Transition's Guard property, I hyperlinked to the Body ("Representation Text") of the Named Opaque Expression. I did this for multiple transitions of the State Machine. Further I made a change to the Opaque Expression and the change was reflected in the Guard of all the linked Transitions.
If this isn't the solution your desire, I apologize. Best of Luck.
Regards,
Geoff