During the lead up to Oracle Solaris 11.2 GA, I noticed that I had written an article back last year that never got published about understanding IPS package versioning. If you haven't yet had a chance to look at Oracle Solaris 11, one of the really great changes that we introduced was completely replacing the packaging mechanism from the rather legacy SVR4 packaging system to the network based Image Packaging System. IPS relies on the fact that ZFS is the underlying file system using a feature called ZFS Boot Environments, allowing us to take advantage of snapshots and clones while updating systems. This means that administrators can perform a system update while still having the old environment to fallback to if something goes wrong. There was a similar concept in Oracle Solaris 10, but was quite primitive by comparison.
And so to the document in question. IPS uses a pretty comprehensive versioning system to allow it to calculate how to go about performing a system update, or indeed any individual software package. We use a series of package constraints on the system to ensure that administrators are updating their software to a well known, and tested state. By contrast, Oracle Solaris 10 essentially let you update or apply any patches you wanted, often leading our customers down a very un-tested path. It's useful to understand this versioning system at times so I've written a useful article that covers some of this.
Take a read of Understanding Oracle Solaris 11 Package Versioning.