Help with temporal type semantics

I would like to ask for help with finding references to work
on type semantics that involve a notion of time.  I'm
working on a type system for a functional language used
in event systems.  For example, a type may represent
the sequence of two events e1 and e2, so the semantics
needs to involve a time-ordering of the sets of instances of
the two events.

Any help would be much appreciated.

Simon Courtenage
University of Westminster