We're tweaking the naming convention used by Oracle Solaris SRUs (Support Repository Updates) to use a 5-digit version taxonomy.

For example, Oracle Solaris 11.1.6.4.0

The digits represent Release.Update.SRU.Build.Respin

For the above example, Oracle Solaris 11.1 SRU 6.4. 
— Solaris 11 SRU naming convention change (Solaris 11 Maintenance Lifecycle)

I saw this one coming when I saw the version strings used for pkgs when first introduced in Solaris 11, especially the "entire" pkg, and have been eager to use this method of identifying Solaris 11 release and SRU but have held off for fear of causing confusion. Well not anymore as it's now official.

So don't be surprised when your support engineer starts referring to Solaris 11.1.6.4.0 in your SRs, and even then Solaris will probably be shortened to just "S", ie S11.1.6.4.0.