Solaris has moved to a continuous update delivery model

Oracle Company reported Applying a continuous update delivery model to Solaris, whereby for the foreseeable future, new features and fresh package versions will appear in the Solaris 11.4 branch as part of monthly updates, without generating a new major release of Solaris 11.5.

The proposed model, which implies the delivery of new functionality in frequently released small versions, will speed up the delivery of new features to users and smooth the transition between versions. Support for Oracle Solaris 11 will continue until at least 2034.

Source: opennet.ru