  Relative observability has been introduced and studied in the framework of
partially observed discrete-event systems as a condition stronger than
observability, but weaker than normality. However, unlike observability,
relative observability is closed under language unions, which makes it
interesting for practical applications. In this paper, we investigate this
notion in the framework of coordination control. We prove that conditional
normality is a stronger condition than conditional (strong) relative
observability, hence conditional strong relative observability can be used in
coordination control instead of conditional normality, and present a
distributive procedure for the computation of a conditionally controllable and
conditionally observable sublanguage of the specification that contains the
supremal conditionally strong relative observable sublanguage.
