If the system under test has multiple interfaces/ports and these
are physically distributed then in testing we place a tester at
each port. If these testers cannot directly communicate with one
another and there is no global clock then we are testing in the
distributed test architecture. If the distributed test
architecture is used then there may be input sequences that cannot
be applied in testing without introducing controllability
problems. Additionally, observability problems can allow fault
masking. In this paper we consider the situation in which the
testers can apply a status message: an input that causes the
system under test to identify its current state. We show how such
a status message can be used in order to overcome controllability
and observability problems
