Sun Cluster release date vs update

I have also compiled a list for Sun Cluster updates vs release date;

Sun Cluster 3.0 – initial release
u1   7/01
u2   5/02
u3   12/01

Sun Cluster 3.1 – initial release 5/03
u1   10/03
u2   4/04
u3   9/04
u4   8/05