Another Bizarre Constellation

You had the .NET 2.0 System assembly and friends last time.  This time it's the turn of System.EnterpriseServices.  The boxes represent 'expanded' assemblies with all references shown (except to System and mscorlib).  The odd thing here is that 'System.Transations' has a reference to itself!  It seems to be the only assembly in the entire framework like this.  I don't know if this is an artifact of how they're setting up circular references or by design.  Can anyone shed some light on this?