The ``++ServiceContract++`` attribute specifies that a class or interface defines the communication contract of a Windows Communication Foundation (WCF) service. The service operations of this class or interface are defined by ``++OperationContract++`` attributes added to methods. It doesn't make sense to define a contract without any service operations; thus, in a ``++ServiceContract++`` class or interface at least one method should be annotated with ``++OperationContract++``. Similarly, WCF only serves ``++OperationContract++`` methods that are defined inside ``++ServiceContract++`` classes or interfaces; thus, this rule also checks that ``++ServiceContract++`` is added to the containing type of ``++OperationContract++`` methods.
