Hello everybody,

I have a sequence diagram with two lifelines, one message, and two
Behavior Execution Specification (one on the left lifeline, and one on the right lifeline)
see attached file please

The message send is aligned with the execution specification start
on the left, while the message receive is not aligned with the execution specification start on the right (it occurs after that)
I have highlighted what I mean in the attached figure

I am wondering if the UML model contains any information about the fact
that two events in the lifeline occurs at the same time instant (like
the message send event and the execution specification start in the left lifeline)

any help is appreciated,
thank you