Enterprise Application Integration (EAI) often requires a loosely coupled event-based architecture in which timing and statistical measures are important. Statistical constraints are proposed to address some of these requirements, although they may well have broader applicability. This idea is extended to the use of approximate terms such as “some” that can be given a statistical interpretation, as in “Some fault reports give rise to subscriptions.” These can be a convenient way of expressing constraints that are important to the application architecture but are not absolute — abstraction through approximation. They may be used to annotate diagrams in UML and are based on the existing Object Constraint Language (OCL) (1). Some of the examples use a more flexible syntax that is the subject of another paper (2).